1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
|
# sqlalchemy/schema.py
# Copyright (C) 2005-2011 the SQLAlchemy authors and contributors <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""The schema module provides the building blocks for database metadata.
Each element within this module describes a database entity which can be
created and dropped, or is otherwise part of such an entity. Examples include
tables, columns, sequences, and indexes.
All entities are subclasses of :class:`~sqlalchemy.schema.SchemaItem`, and as
defined in this module they are intended to be agnostic of any vendor-specific
constructs.
A collection of entities are grouped into a unit called
:class:`~sqlalchemy.schema.MetaData`. MetaData serves as a logical grouping of
schema elements, and can also be associated with an actual database connection
such that operations involving the contained elements can contact the database
as needed.
Two of the elements here also build upon their "syntactic" counterparts, which
are defined in :class:`~sqlalchemy.sql.expression.`, specifically
:class:`~sqlalchemy.schema.Table` and :class:`~sqlalchemy.schema.Column`.
Since these objects are part of the SQL expression language, they are usable
as components in SQL expressions.
"""
import re, inspect
from sqlalchemy import exc, util, dialects
from sqlalchemy.sql import expression, visitors
from sqlalchemy import event, events
sqlutil = util.importlater("sqlalchemy.sql", "util")
url = util.importlater("sqlalchemy.engine", "url")
sqltypes = util.importlater("sqlalchemy", "types")
__all__ = ['SchemaItem', 'Table', 'Column', 'ForeignKey', 'Sequence', 'Index',
'ForeignKeyConstraint', 'PrimaryKeyConstraint', 'CheckConstraint',
'UniqueConstraint', 'DefaultGenerator', 'Constraint', 'MetaData',
'ThreadLocalMetaData', 'SchemaVisitor', 'PassiveDefault',
'DefaultClause', 'FetchedValue', 'ColumnDefault', 'DDL',
'CreateTable', 'DropTable', 'CreateSequence', 'DropSequence',
'AddConstraint', 'DropConstraint',
]
__all__.sort()
RETAIN_SCHEMA = util.symbol('retain_schema')
class SchemaItem(events.SchemaEventTarget, visitors.Visitable):
"""Base class for items that define a database schema."""
__visit_name__ = 'schema_item'
quote = None
def _init_items(self, *args):
"""Initialize the list of child items for this SchemaItem."""
for item in args:
if item is not None:
item._set_parent_with_dispatch(self)
def get_children(self, **kwargs):
"""used to allow SchemaVisitor access"""
return []
def __repr__(self):
return "%s()" % self.__class__.__name__
@util.memoized_property
def info(self):
return {}
def _get_table_key(name, schema):
if schema is None:
return name
else:
return schema + "." + name
class Table(SchemaItem, expression.TableClause):
"""Represent a table in a database.
e.g.::
mytable = Table("mytable", metadata,
Column('mytable_id', Integer, primary_key=True),
Column('value', String(50))
)
The :class:`.Table` object constructs a unique instance of itself based on its
name and optionl schema name within the given :class:`.MetaData` object.
Calling the :class:`.Table`
constructor with the same name and same :class:`.MetaData` argument
a second time will return the *same* :class:`.Table` object - in this way
the :class:`.Table` constructor acts as a registry function.
Constructor arguments are as follows:
:param name: The name of this table as represented in the database.
This property, along with the *schema*, indicates the *singleton
identity* of this table in relation to its parent :class:`.MetaData`.
Additional calls to :class:`.Table` with the same name, metadata,
and schema name will return the same :class:`.Table` object.
Names which contain no upper case characters
will be treated as case insensitive names, and will not be quoted
unless they are a reserved word. Names with any number of upper
case characters will be quoted and sent exactly. Note that this
behavior applies even for databases which standardize upper
case names as case insensitive such as Oracle.
:param metadata: a :class:`.MetaData` object which will contain this
table. The metadata is used as a point of association of this table
with other tables which are referenced via foreign key. It also
may be used to associate this table with a particular
:class:`~sqlalchemy.engine.base.Connectable`.
:param \*args: Additional positional arguments are used primarily
to add the list of :class:`.Column` objects contained within this
table. Similar to the style of a CREATE TABLE statement, other
:class:`.SchemaItem` constructs may be added here, including
:class:`.PrimaryKeyConstraint`, and :class:`.ForeignKeyConstraint`.
:param autoload: Defaults to False: the Columns for this table should
be reflected from the database. Usually there will be no Column
objects in the constructor if this property is set.
:param autoload_with: If autoload==True, this is an optional Engine
or Connection instance to be used for the table reflection. If
``None``, the underlying MetaData's bound connectable will be used.
:param extend_existing: When ``True``, indicates that if this Table is already
present in the given :class:`.MetaData`, apply further arguments within
the constructor to the existing :class:`.Table`.
If extend_existing or keep_existing are not set, an error is
raised if additional table modifiers are specified when
the given :class:`.Table` is already present in the :class:`.MetaData`.
:param implicit_returning: True by default - indicates that
RETURNING can be used by default to fetch newly inserted primary key
values, for backends which support this. Note that
create_engine() also provides an implicit_returning flag.
:param include_columns: A list of strings indicating a subset of
columns to be loaded via the ``autoload`` operation; table columns who
aren't present in this list will not be represented on the resulting
``Table`` object. Defaults to ``None`` which indicates all columns
should be reflected.
:param info: A dictionary which defaults to ``{}``. A space to store
application specific data. This must be a dictionary.
:param keep_existing: When ``True``, indicates that if this Table
is already present in the given :class:`.MetaData`, ignore
further arguments within the constructor to the existing
:class:`.Table`, and return the :class:`.Table` object as
originally created. This is to allow a function that wishes
to define a new :class:`.Table` on first call, but on
subsequent calls will return the same :class:`.Table`,
without any of the declarations (particularly constraints)
being applied a second time. Also see extend_existing.
If extend_existing or keep_existing are not set, an error is
raised if additional table modifiers are specified when
the given :class:`.Table` is already present in the :class:`.MetaData`.
:param listeners: A list of tuples of the form ``(<eventname>, <fn>)``
which will be passed to :func:`.event.listen` upon construction.
This alternate hook to :func:`.event.listen` allows the establishment
of a listener function specific to this :class:`.Table` before
the "autoload" process begins. Particularly useful for
the :meth:`.events.column_reflect` event::
def listen_for_reflect(table, column_info):
"handle the column reflection event"
# ...
t = Table(
'sometable',
autoload=True,
listeners=[
('column_reflect', listen_for_reflect)
])
:param mustexist: When ``True``, indicates that this Table must already
be present in the given :class:`.MetaData`` collection, else
an exception is raised.
:param prefixes:
A list of strings to insert after CREATE in the CREATE TABLE
statement. They will be separated by spaces.
:param quote: Force quoting of this table's name on or off, corresponding
to ``True`` or ``False``. When left at its default of ``None``,
the column identifier will be quoted according to whether the name is
case sensitive (identifiers with at least one upper case character are
treated as case sensitive), or if it's a reserved word. This flag
is only needed to force quoting of a reserved word which is not known
by the SQLAlchemy dialect.
:param quote_schema: same as 'quote' but applies to the schema identifier.
:param schema: The *schema name* for this table, which is required if
the table resides in a schema other than the default selected schema
for the engine's database connection. Defaults to ``None``.
:param useexisting: Deprecated. Use extend_existing.
"""
__visit_name__ = 'table'
def __new__(cls, *args, **kw):
if not args:
# python3k pickle seems to call this
return object.__new__(cls)
try:
name, metadata, args = args[0], args[1], args[2:]
except IndexError:
raise TypeError("Table() takes at least two arguments")
schema = kw.get('schema', None)
keep_existing = kw.pop('keep_existing', False)
extend_existing = kw.pop('extend_existing', False)
if 'useexisting' in kw:
util.warn_deprecated("useexisting is deprecated. Use extend_existing.")
if extend_existing:
raise exc.ArgumentError("useexisting is synonymous "
"with extend_existing.")
extend_existing = kw.pop('useexisting', False)
if keep_existing and extend_existing:
raise exc.ArgumentError("keep_existing and extend_existing "
"are mutually exclusive.")
mustexist = kw.pop('mustexist', False)
key = _get_table_key(name, schema)
if key in metadata.tables:
if not keep_existing and not extend_existing and bool(args):
raise exc.InvalidRequestError(
"Table '%s' is already defined for this MetaData "
"instance. Specify 'extend_existing=True' "
"to redefine "
"options and columns on an "
"existing Table object." % key)
table = metadata.tables[key]
if extend_existing:
table._init_existing(*args, **kw)
return table
else:
if mustexist:
raise exc.InvalidRequestError(
"Table '%s' not defined" % (key))
table = object.__new__(cls)
table.dispatch.before_parent_attach(table, metadata)
metadata._add_table(name, schema, table)
try:
table._init(name, metadata, *args, **kw)
table.dispatch.after_parent_attach(table, metadata)
return table
except:
metadata._remove_table(name, schema)
raise
def __init__(self, *args, **kw):
"""Constructor for :class:`~.schema.Table`.
This method is a no-op. See the top-level
documentation for :class:`~.schema.Table`
for constructor arguments.
"""
# __init__ is overridden to prevent __new__ from
# calling the superclass constructor.
def _init(self, name, metadata, *args, **kwargs):
super(Table, self).__init__(name)
self.metadata = metadata
self.schema = kwargs.pop('schema', None)
self.indexes = set()
self.constraints = set()
self._columns = expression.ColumnCollection()
PrimaryKeyConstraint()._set_parent_with_dispatch(self)
self.foreign_keys = set()
self._extra_dependencies = set()
self.kwargs = {}
if self.schema is not None:
self.fullname = "%s.%s" % (self.schema, self.name)
else:
self.fullname = self.name
autoload = kwargs.pop('autoload', False)
autoload_with = kwargs.pop('autoload_with', None)
include_columns = kwargs.pop('include_columns', None)
self.implicit_returning = kwargs.pop('implicit_returning', True)
self.quote = kwargs.pop('quote', None)
self.quote_schema = kwargs.pop('quote_schema', None)
if 'info' in kwargs:
self.info = kwargs.pop('info')
if 'listeners' in kwargs:
listeners = kwargs.pop('listeners')
for evt, fn in listeners:
event.listen(self, evt, fn)
self._prefixes = kwargs.pop('prefixes', [])
self._extra_kwargs(**kwargs)
# load column definitions from the database if 'autoload' is defined
# we do it after the table is in the singleton dictionary to support
# circular foreign keys
if autoload:
if autoload_with:
autoload_with.reflecttable(self,
include_columns=include_columns)
else:
_bind_or_error(metadata,
msg="No engine is bound to this Table's MetaData. "
"Pass an engine to the Table via "
"autoload_with=<someengine>, "
"or associate the MetaData with an engine via "
"metadata.bind=<someengine>").\
reflecttable(self, include_columns=include_columns)
# initialize all the column, etc. objects. done after reflection to
# allow user-overrides
self._init_items(*args)
@property
def _sorted_constraints(self):
"""Return the set of constraints as a list, sorted by creation order."""
return sorted(self.constraints, key=lambda c:c._creation_order)
def _init_existing(self, *args, **kwargs):
autoload = kwargs.pop('autoload', False)
autoload_with = kwargs.pop('autoload_with', None)
schema = kwargs.pop('schema', None)
if schema and schema != self.schema:
raise exc.ArgumentError(
"Can't change schema of existing table from '%s' to '%s'",
(self.schema, schema))
include_columns = kwargs.pop('include_columns', None)
if include_columns:
for c in self.c:
if c.name not in include_columns:
self._columns.remove(c)
for key in ('quote', 'quote_schema'):
if key in kwargs:
setattr(self, key, kwargs.pop(key))
if 'info' in kwargs:
self.info = kwargs.pop('info')
self._extra_kwargs(**kwargs)
self._init_items(*args)
def _extra_kwargs(self, **kwargs):
# validate remaining kwargs that they all specify DB prefixes
if len([k for k in kwargs
if not re.match(
r'^(?:%s)_' %
'|'.join(dialects.__all__), k
)
]):
raise TypeError(
"Invalid argument(s) for Table: %r" % kwargs.keys())
self.kwargs.update(kwargs)
def _init_collections(self):
pass
@util.memoized_property
def _autoincrement_column(self):
for col in self.primary_key:
if col.autoincrement and \
issubclass(col.type._type_affinity, sqltypes.Integer) and \
not col.foreign_keys and \
isinstance(col.default, (type(None), Sequence)) and \
(col.server_default is None or col.server_default.reflected):
return col
@property
def key(self):
return _get_table_key(self.name, self.schema)
def __repr__(self):
return "Table(%s)" % ', '.join(
[repr(self.name)] + [repr(self.metadata)] +
[repr(x) for x in self.columns] +
["%s=%s" % (k, repr(getattr(self, k))) for k in ['schema']])
def __str__(self):
return _get_table_key(self.description, self.schema)
@property
def bind(self):
"""Return the connectable associated with this Table."""
return self.metadata and self.metadata.bind or None
def add_is_dependent_on(self, table):
"""Add a 'dependency' for this Table.
This is another Table object which must be created
first before this one can, or dropped after this one.
Usually, dependencies between tables are determined via
ForeignKey objects. However, for other situations that
create dependencies outside of foreign keys (rules, inheriting),
this method can manually establish such a link.
"""
self._extra_dependencies.add(table)
def append_column(self, column):
"""Append a :class:`~.schema.Column` to this :class:`~.schema.Table`.
The "key" of the newly added :class:`~.schema.Column`, i.e. the
value of its ``.key`` attribute, will then be available
in the ``.c`` collection of this :class:`~.schema.Table`, and the
column definition will be included in any CREATE TABLE, SELECT,
UPDATE, etc. statements generated from this :class:`~.schema.Table`
construct.
Note that this does **not** change the definition of the table
as it exists within any underlying database, assuming that
table has already been created in the database. Relational
databases support the addition of columns to existing tables
using the SQL ALTER command, which would need to be
emitted for an already-existing table that doesn't contain
the newly added column.
"""
column._set_parent_with_dispatch(self)
def append_constraint(self, constraint):
"""Append a :class:`~.schema.Constraint` to this :class:`~.schema.Table`.
This has the effect of the constraint being included in any
future CREATE TABLE statement, assuming specific DDL creation
events have not been associated with the given :class:`~.schema.Constraint`
object.
Note that this does **not** produce the constraint within the
relational database automatically, for a table that already exists
in the database. To add a constraint to an
existing relational database table, the SQL ALTER command must
be used. SQLAlchemy also provides the :class:`.AddConstraint` construct
which can produce this SQL when invoked as an executable clause.
"""
constraint._set_parent_with_dispatch(self)
def append_ddl_listener(self, event_name, listener):
"""Append a DDL event listener to this ``Table``.
Deprecated. See :class:`.DDLEvents`.
"""
def adapt_listener(target, connection, **kw):
listener(event_name, target, connection, **kw)
event.listen(self, "" + event_name.replace('-', '_'), adapt_listener)
def _set_parent(self, metadata):
metadata._add_table(self.name, self.schema, self)
self.metadata = metadata
def get_children(self, column_collections=True,
schema_visitor=False, **kw):
if not schema_visitor:
return expression.TableClause.get_children(
self, column_collections=column_collections, **kw)
else:
if column_collections:
return list(self.columns)
else:
return []
def exists(self, bind=None):
"""Return True if this table exists."""
if bind is None:
bind = _bind_or_error(self)
return bind.run_callable(bind.dialect.has_table,
self.name, schema=self.schema)
def create(self, bind=None, checkfirst=False):
"""Issue a ``CREATE`` statement for this table.
See also ``metadata.create_all()``.
"""
if bind is None:
bind = _bind_or_error(self)
bind.create(self, checkfirst=checkfirst)
def drop(self, bind=None, checkfirst=False):
"""Issue a ``DROP`` statement for this table.
See also ``metadata.drop_all()``.
"""
if bind is None:
bind = _bind_or_error(self)
bind.drop(self, checkfirst=checkfirst)
def tometadata(self, metadata, schema=RETAIN_SCHEMA):
"""Return a copy of this :class:`.Table` associated with a different
:class:`.MetaData`.
E.g.::
# create two metadata
meta1 = MetaData('sqlite:///querytest.db')
meta2 = MetaData()
# load 'users' from the sqlite engine
users_table = Table('users', meta1, autoload=True)
# create the same Table object for the plain metadata
users_table_2 = users_table.tometadata(meta2)
"""
if schema is RETAIN_SCHEMA:
schema = self.schema
key = _get_table_key(self.name, schema)
if key in metadata.tables:
util.warn("Table '%s' already exists within the given "
"MetaData - not copying." % self.description)
return metadata.tables[key]
args = []
for c in self.columns:
args.append(c.copy(schema=schema))
for c in self.constraints:
args.append(c.copy(schema=schema))
table = Table(
self.name, metadata, schema=schema,
*args, **self.kwargs
)
for index in self.indexes:
# skip indexes that would be generated
# by the 'index' flag on Column
if len(index.columns) == 1 and \
list(index.columns)[0].index:
continue
Index(index.name,
unique=index.unique,
*[table.c[col] for col in index.columns.keys()],
**index.kwargs)
table.dispatch._update(self.dispatch)
return table
class Column(SchemaItem, expression.ColumnClause):
"""Represents a column in a database table."""
__visit_name__ = 'column'
def __init__(self, *args, **kwargs):
"""
Construct a new ``Column`` object.
:param name: The name of this column as represented in the database.
This argument may be the first positional argument, or specified
via keyword.
Names which contain no upper case characters
will be treated as case insensitive names, and will not be quoted
unless they are a reserved word. Names with any number of upper
case characters will be quoted and sent exactly. Note that this
behavior applies even for databases which standardize upper
case names as case insensitive such as Oracle.
The name field may be omitted at construction time and applied
later, at any time before the Column is associated with a
:class:`.Table`. This is to support convenient
usage within the :mod:`~sqlalchemy.ext.declarative` extension.
:param type\_: The column's type, indicated using an instance which
subclasses :class:`~sqlalchemy.types.TypeEngine`. If no arguments
are required for the type, the class of the type can be sent
as well, e.g.::
# use a type with arguments
Column('data', String(50))
# use no arguments
Column('level', Integer)
The ``type`` argument may be the second positional argument
or specified by keyword.
There is partial support for automatic detection of the
type based on that of a :class:`.ForeignKey` associated
with this column, if the type is specified as ``None``.
However, this feature is not fully implemented and
may not function in all cases.
:param \*args: Additional positional arguments include various
:class:`.SchemaItem` derived constructs which will be applied
as options to the column. These include instances of
:class:`.Constraint`, :class:`.ForeignKey`, :class:`.ColumnDefault`,
and :class:`.Sequence`. In some cases an equivalent keyword
argument is available such as ``server_default``, ``default``
and ``unique``.
:param autoincrement: This flag may be set to ``False`` to
indicate an integer primary key column that should not be
considered to be the "autoincrement" column, that is
the integer primary key column which generates values
implicitly upon INSERT and whose value is usually returned
via the DBAPI cursor.lastrowid attribute. It defaults
to ``True`` to satisfy the common use case of a table
with a single integer primary key column. If the table
has a composite primary key consisting of more than one
integer column, set this flag to True only on the
column that should be considered "autoincrement".
The setting *only* has an effect for columns which are:
* Integer derived (i.e. INT, SMALLINT, BIGINT).
* Part of the primary key
* Are not referenced by any foreign keys
* have no server side or client side defaults (with the exception
of Postgresql SERIAL).
The setting has these two effects on columns that meet the
above criteria:
* DDL issued for the column will include database-specific
keywords intended to signify this column as an
"autoincrement" column, such as AUTO INCREMENT on MySQL,
SERIAL on Postgresql, and IDENTITY on MS-SQL. It does
*not* issue AUTOINCREMENT for SQLite since this is a
special SQLite flag that is not required for autoincrementing
behavior. See the SQLite dialect documentation for
information on SQLite's AUTOINCREMENT.
* The column will be considered to be available as
cursor.lastrowid or equivalent, for those dialects which
"post fetch" newly inserted identifiers after a row has
been inserted (SQLite, MySQL, MS-SQL). It does not have
any effect in this regard for databases that use sequences
to generate primary key identifiers (i.e. Firebird, Postgresql,
Oracle).
:param default: A scalar, Python callable, or
:class:`~sqlalchemy.sql.expression.ClauseElement` representing the
*default value* for this column, which will be invoked upon insert
if this column is otherwise not specified in the VALUES clause of
the insert. This is a shortcut to using :class:`.ColumnDefault` as
a positional argument.
Contrast this argument to ``server_default`` which creates a
default generator on the database side.
:param doc: optional String that can be used by the ORM or similar
to document attributes. This attribute does not render SQL
comments (a future attribute 'comment' will achieve that).
:param key: An optional string identifier which will identify this
``Column`` object on the :class:`.Table`. When a key is provided,
this is the only identifier referencing the ``Column`` within the
application, including ORM attribute mapping; the ``name`` field
is used only when rendering SQL.
:param index: When ``True``, indicates that the column is indexed.
This is a shortcut for using a :class:`.Index` construct on the
table. To specify indexes with explicit names or indexes that
contain multiple columns, use the :class:`.Index` construct
instead.
:param info: A dictionary which defaults to ``{}``. A space to store
application specific data. This must be a dictionary.
:param nullable: If set to the default of ``True``, indicates the
column will be rendered as allowing NULL, else it's rendered as
NOT NULL. This parameter is only used when issuing CREATE TABLE
statements.
:param onupdate: A scalar, Python callable, or
:class:`~sqlalchemy.sql.expression.ClauseElement` representing a
default value to be applied to the column within UPDATE
statements, which wil be invoked upon update if this column is not
present in the SET clause of the update. This is a shortcut to
using :class:`.ColumnDefault` as a positional argument with
``for_update=True``.
:param primary_key: If ``True``, marks this column as a primary key
column. Multiple columns can have this flag set to specify
composite primary keys. As an alternative, the primary key of a
:class:`.Table` can be specified via an explicit
:class:`.PrimaryKeyConstraint` object.
:param server_default: A :class:`.FetchedValue` instance, str, Unicode
or :func:`~sqlalchemy.sql.expression.text` construct representing
the DDL DEFAULT value for the column.
String types will be emitted as-is, surrounded by single quotes::
Column('x', Text, server_default="val")
x TEXT DEFAULT 'val'
A :func:`~sqlalchemy.sql.expression.text` expression will be
rendered as-is, without quotes::
Column('y', DateTime, server_default=text('NOW()'))0
y DATETIME DEFAULT NOW()
Strings and text() will be converted into a :class:`.DefaultClause`
object upon initialization.
Use :class:`.FetchedValue` to indicate that an already-existing
column will generate a default value on the database side which
will be available to SQLAlchemy for post-fetch after inserts. This
construct does not specify any DDL and the implementation is left
to the database, such as via a trigger.
:param server_onupdate: A :class:`.FetchedValue` instance
representing a database-side default generation function. This
indicates to SQLAlchemy that a newly generated value will be
available after updates. This construct does not specify any DDL
and the implementation is left to the database, such as via a
trigger.
:param quote: Force quoting of this column's name on or off,
corresponding to ``True`` or ``False``. When left at its default
of ``None``, the column identifier will be quoted according to
whether the name is case sensitive (identifiers with at least one
upper case character are treated as case sensitive), or if it's a
reserved word. This flag is only needed to force quoting of a
reserved word which is not known by the SQLAlchemy dialect.
:param unique: When ``True``, indicates that this column contains a
unique constraint, or if ``index`` is ``True`` as well, indicates
that the :class:`.Index` should be created with the unique flag.
To specify multiple columns in the constraint/index or to specify
an explicit name, use the :class:`.UniqueConstraint` or
:class:`.Index` constructs explicitly.
"""
name = kwargs.pop('name', None)
type_ = kwargs.pop('type_', None)
args = list(args)
if args:
if isinstance(args[0], basestring):
if name is not None:
raise exc.ArgumentError(
"May not pass name positionally and as a keyword.")
name = args.pop(0)
if args:
coltype = args[0]
if (isinstance(coltype, sqltypes.TypeEngine) or
(isinstance(coltype, type) and
issubclass(coltype, sqltypes.TypeEngine))):
if type_ is not None:
raise exc.ArgumentError(
"May not pass type_ positionally and as a keyword.")
type_ = args.pop(0)
no_type = type_ is None
super(Column, self).__init__(name, None, type_)
self.key = kwargs.pop('key', name)
self.primary_key = kwargs.pop('primary_key', False)
self.nullable = kwargs.pop('nullable', not self.primary_key)
self.default = kwargs.pop('default', None)
self.server_default = kwargs.pop('server_default', None)
self.server_onupdate = kwargs.pop('server_onupdate', None)
self.index = kwargs.pop('index', None)
self.unique = kwargs.pop('unique', None)
self.quote = kwargs.pop('quote', None)
self.doc = kwargs.pop('doc', None)
self.onupdate = kwargs.pop('onupdate', None)
self.autoincrement = kwargs.pop('autoincrement', True)
self.constraints = set()
self.foreign_keys = set()
# check if this Column is proxying another column
if '_proxies' in kwargs:
self.proxies = kwargs.pop('_proxies')
# otherwise, add DDL-related events
elif isinstance(self.type, sqltypes.SchemaType):
self.type._set_parent_with_dispatch(self)
if self.default is not None:
if isinstance(self.default, (ColumnDefault, Sequence)):
args.append(self.default)
else:
if getattr(self.type, '_warn_on_bytestring', False):
# Py3K
#if isinstance(self.default, bytes):
# Py2K
if isinstance(self.default, str):
# end Py2K
util.warn("Unicode column received non-unicode "
"default value.")
args.append(ColumnDefault(self.default))
if self.server_default is not None:
if isinstance(self.server_default, FetchedValue):
args.append(self.server_default)
else:
args.append(DefaultClause(self.server_default))
if self.onupdate is not None:
if isinstance(self.onupdate, (ColumnDefault, Sequence)):
args.append(self.onupdate)
else:
args.append(ColumnDefault(self.onupdate, for_update=True))
if self.server_onupdate is not None:
if isinstance(self.server_onupdate, FetchedValue):
args.append(self.server_onupdate)
else:
args.append(DefaultClause(self.server_onupdate,
for_update=True))
self._init_items(*args)
if not self.foreign_keys and no_type:
raise exc.ArgumentError("'type' is required on Column objects "
"which have no foreign keys.")
util.set_creation_order(self)
if 'info' in kwargs:
self.info = kwargs.pop('info')
if kwargs:
raise exc.ArgumentError(
"Unknown arguments passed to Column: " + repr(kwargs.keys()))
def __str__(self):
if self.name is None:
return "(no name)"
elif self.table is not None:
if self.table.named_with_column:
return (self.table.description + "." + self.description)
else:
return self.description
else:
return self.description
def references(self, column):
"""Return True if this Column references the given column via foreign
key."""
for fk in self.foreign_keys:
if fk.column.proxy_set.intersection(column.proxy_set):
return True
else:
return False
def append_foreign_key(self, fk):
fk._set_parent_with_dispatch(self)
def __repr__(self):
kwarg = []
if self.key != self.name:
kwarg.append('key')
if self.primary_key:
kwarg.append('primary_key')
if not self.nullable:
kwarg.append('nullable')
if self.onupdate:
kwarg.append('onupdate')
if self.default:
kwarg.append('default')
if self.server_default:
kwarg.append('server_default')
return "Column(%s)" % ', '.join(
[repr(self.name)] + [repr(self.type)] +
[repr(x) for x in self.foreign_keys if x is not None] +
[repr(x) for x in self.constraints] +
[(self.table is not None and "table=<%s>" %
self.table.description or "")] +
["%s=%s" % (k, repr(getattr(self, k))) for k in kwarg])
def _set_parent(self, table):
if not self.name:
raise exc.ArgumentError(
"Column must be constructed with a non-blank name or "
"assign a non-blank .name before adding to a Table.")
if self.key is None:
self.key = self.name
if getattr(self, 'table', None) is not None:
raise exc.ArgumentError(
"Column object already assigned to Table '%s'" %
self.table.description)
if self.key in table._columns:
col = table._columns.get(self.key)
for fk in list(col.foreign_keys):
col.foreign_keys.remove(fk)
table.foreign_keys.remove(fk)
if fk.constraint in table.constraints:
# this might have been removed
# already, if it's a composite constraint
# and more than one col being replaced
table.constraints.remove(fk.constraint)
table._columns.replace(self)
if self.primary_key:
table.primary_key._replace(self)
elif self.key in table.primary_key:
raise exc.ArgumentError(
"Trying to redefine primary-key column '%s' as a "
"non-primary-key column on table '%s'" % (
self.key, table.fullname))
self.table = table
if self.index:
if isinstance(self.index, basestring):
raise exc.ArgumentError(
"The 'index' keyword argument on Column is boolean only. "
"To create indexes with a specific name, create an "
"explicit Index object external to the Table.")
Index(expression._generated_label('ix_%s' % self._label), self, unique=self.unique)
elif self.unique:
if isinstance(self.unique, basestring):
raise exc.ArgumentError(
"The 'unique' keyword argument on Column is boolean "
"only. To create unique constraints or indexes with a "
"specific name, append an explicit UniqueConstraint to "
"the Table's list of elements, or create an explicit "
"Index object external to the Table.")
table.append_constraint(UniqueConstraint(self.key))
def _on_table_attach(self, fn):
if self.table is not None:
fn(self, self.table)
event.listen(self, 'after_parent_attach', fn)
def copy(self, **kw):
"""Create a copy of this ``Column``, unitialized.
This is used in ``Table.tometadata``.
"""
# Constraint objects plus non-constraint-bound ForeignKey objects
args = \
[c.copy(**kw) for c in self.constraints] + \
[c.copy(**kw) for c in self.foreign_keys if not c.constraint]
c = Column(
name=self.name,
type_=self.type,
key = self.key,
primary_key = self.primary_key,
nullable = self.nullable,
unique = self.unique,
quote=self.quote,
index=self.index,
autoincrement=self.autoincrement,
default=self.default,
server_default=self.server_default,
onupdate=self.onupdate,
server_onupdate=self.server_onupdate,
info=self.info,
doc=self.doc,
*args
)
c.dispatch._update(self.dispatch)
return c
def _make_proxy(self, selectable, name=None):
"""Create a *proxy* for this column.
This is a copy of this ``Column`` referenced by a different parent
(such as an alias or select statement). The column should
be used only in select scenarios, as its full DDL/default
information is not transferred.
"""
fk = [ForeignKey(f.column) for f in self.foreign_keys]
if name is None and self.name is None:
raise exc.InvalidRequestError("Cannot initialize a sub-selectable"
" with this Column object until it's 'name' has "
"been assigned.")
try:
c = self._constructor(
name or self.name,
self.type,
key = name or self.key,
primary_key = self.primary_key,
nullable = self.nullable,
quote=self.quote, _proxies=[self], *fk)
except TypeError, e:
# Py3K
#raise TypeError(
# "Could not create a copy of this %r object. "
# "Ensure the class includes a _constructor() "
# "attribute or method which accepts the "
# "standard Column constructor arguments, or "
# "references the Column class itself." % self.__class__) from e
# Py2K
raise TypeError(
"Could not create a copy of this %r object. "
"Ensure the class includes a _constructor() "
"attribute or method which accepts the "
"standard Column constructor arguments, or "
"references the Column class itself. "
"Original error: %s" % (self.__class__, e))
# end Py2K
c.table = selectable
selectable._columns.add(c)
if self.primary_key:
selectable.primary_key.add(c)
c.dispatch.after_parent_attach(c, selectable)
return c
def get_children(self, schema_visitor=False, **kwargs):
if schema_visitor:
return [x for x in (self.default, self.onupdate)
if x is not None] + \
list(self.foreign_keys) + list(self.constraints)
else:
return expression.ColumnClause.get_children(self, **kwargs)
class ForeignKey(SchemaItem):
"""Defines a dependency between two columns.
``ForeignKey`` is specified as an argument to a :class:`.Column` object,
e.g.::
t = Table("remote_table", metadata,
Column("remote_id", ForeignKey("main_table.id"))
)
Note that ``ForeignKey`` is only a marker object that defines
a dependency between two columns. The actual constraint
is in all cases represented by the :class:`.ForeignKeyConstraint`
object. This object will be generated automatically when
a ``ForeignKey`` is associated with a :class:`.Column` which
in turn is associated with a :class:`.Table`. Conversely,
when :class:`.ForeignKeyConstraint` is applied to a :class:`.Table`,
``ForeignKey`` markers are automatically generated to be
present on each associated :class:`.Column`, which are also
associated with the constraint object.
Note that you cannot define a "composite" foreign key constraint,
that is a constraint between a grouping of multiple parent/child
columns, using ``ForeignKey`` objects. To define this grouping,
the :class:`.ForeignKeyConstraint` object must be used, and applied
to the :class:`.Table`. The associated ``ForeignKey`` objects
are created automatically.
The ``ForeignKey`` objects associated with an individual
:class:`.Column` object are available in the `foreign_keys` collection
of that column.
Further examples of foreign key configuration are in
:ref:`metadata_foreignkeys`.
"""
__visit_name__ = 'foreign_key'
def __init__(self, column, _constraint=None, use_alter=False, name=None,
onupdate=None, ondelete=None, deferrable=None,
initially=None, link_to_name=False):
"""
Construct a column-level FOREIGN KEY.
The :class:`.ForeignKey` object when constructed generates a
:class:`.ForeignKeyConstraint` which is associated with the parent
:class:`.Table` object's collection of constraints.
:param column: A single target column for the key relationship. A
:class:`.Column` object or a column name as a string:
``tablename.columnkey`` or ``schema.tablename.columnkey``.
``columnkey`` is the ``key`` which has been assigned to the column
(defaults to the column name itself), unless ``link_to_name`` is
``True`` in which case the rendered name of the column is used.
:param name: Optional string. An in-database name for the key if
`constraint` is not provided.
:param onupdate: Optional string. If set, emit ON UPDATE <value> when
issuing DDL for this constraint. Typical values include CASCADE,
DELETE and RESTRICT.
:param ondelete: Optional string. If set, emit ON DELETE <value> when
issuing DDL for this constraint. Typical values include CASCADE,
DELETE and RESTRICT.
:param deferrable: Optional bool. If set, emit DEFERRABLE or NOT
DEFERRABLE when issuing DDL for this constraint.
:param initially: Optional string. If set, emit INITIALLY <value> when
issuing DDL for this constraint.
:param link_to_name: if True, the string name given in ``column`` is
the rendered name of the referenced column, not its locally
assigned ``key``.
:param use_alter: passed to the underlying
:class:`.ForeignKeyConstraint` to indicate the constraint should be
generated/dropped externally from the CREATE TABLE/ DROP TABLE
statement. See that classes' constructor for details.
"""
self._colspec = column
# the linked ForeignKeyConstraint.
# ForeignKey will create this when parent Column
# is attached to a Table, *or* ForeignKeyConstraint
# object passes itself in when creating ForeignKey
# markers.
self.constraint = _constraint
self.use_alter = use_alter
self.name = name
self.onupdate = onupdate
self.ondelete = ondelete
self.deferrable = deferrable
self.initially = initially
self.link_to_name = link_to_name
def __repr__(self):
return "ForeignKey(%r)" % self._get_colspec()
def copy(self, schema=None):
"""Produce a copy of this :class:`.ForeignKey` object.
The new :class:`.ForeignKey` will not be bound
to any :class:`.Column`.
This method is usually used by the internal
copy procedures of :class:`.Column`, :class:`.Table`,
and :class:`.MetaData`.
:param schema: The returned :class:`.ForeignKey` will
reference the original table and column name, qualified
by the given string schema name.
"""
fk = ForeignKey(
self._get_colspec(schema=schema),
use_alter=self.use_alter,
name=self.name,
onupdate=self.onupdate,
ondelete=self.ondelete,
deferrable=self.deferrable,
initially=self.initially,
link_to_name=self.link_to_name
)
fk.dispatch._update(self.dispatch)
return fk
def _get_colspec(self, schema=None):
"""Return a string based 'column specification' for this :class:`.ForeignKey`.
This is usually the equivalent of the string-based "tablename.colname"
argument first passed to the object's constructor.
"""
if schema:
return schema + "." + self.column.table.name + \
"." + self.column.key
elif isinstance(self._colspec, basestring):
return self._colspec
elif hasattr(self._colspec, '__clause_element__'):
_column = self._colspec.__clause_element__()
else:
_column = self._colspec
return "%s.%s" % (_column.table.fullname, _column.key)
target_fullname = property(_get_colspec)
def references(self, table):
"""Return True if the given :class:`.Table` is referenced by this :class:`.ForeignKey`."""
return table.corresponding_column(self.column) is not None
def get_referent(self, table):
"""Return the :class:`.Column` in the given :class:`.Table`
referenced by this :class:`.ForeignKey`.
Returns None if this :class:`.ForeignKey` does not reference the given
:class:`.Table`.
"""
return table.corresponding_column(self.column)
@util.memoized_property
def column(self):
"""Return the target :class:`.Column` referenced by this :class:`.ForeignKey`.
If this :class:`.ForeignKey` was created using a
string-based target column specification, this
attribute will on first access initiate a resolution
process to locate the referenced remote
:class:`.Column`. The resolution process traverses
to the parent :class:`.Column`, :class:`.Table`, and
:class:`.MetaData` to proceed - if any of these aren't
yet present, an error is raised.
"""
# ForeignKey inits its remote column as late as possible, so tables
# can be defined without dependencies
if isinstance(self._colspec, basestring):
# locate the parent table this foreign key is attached to. we
# use the "original" column which our parent column represents
# (its a list of columns/other ColumnElements if the parent
# table is a UNION)
for c in self.parent.base_columns:
if isinstance(c, Column):
parenttable = c.table
break
else:
raise exc.ArgumentError(
"Parent column '%s' does not descend from a "
"table-attached Column" % str(self.parent))
m = self._colspec.split('.')
if m is None:
raise exc.ArgumentError(
"Invalid foreign key column specification: %s" %
self._colspec)
# A FK between column 'bar' and table 'foo' can be
# specified as 'foo', 'foo.bar', 'dbo.foo.bar',
# 'otherdb.dbo.foo.bar'. Once we have the column name and
# the table name, treat everything else as the schema
# name. Some databases (e.g. Sybase) support
# inter-database foreign keys. See tickets#1341 and --
# indirectly related -- Ticket #594. This assumes that '.'
# will never appear *within* any component of the FK.
(schema, tname, colname) = (None, None, None)
if (len(m) == 1):
tname = m.pop()
else:
colname = m.pop()
tname = m.pop()
if (len(m) > 0):
schema = '.'.join(m)
if _get_table_key(tname, schema) not in parenttable.metadata:
raise exc.NoReferencedTableError(
"Foreign key associated with column '%s' could not find "
"table '%s' with which to generate a "
"foreign key to target column '%s'" % (self.parent, tname, colname),
tname)
table = Table(tname, parenttable.metadata,
mustexist=True, schema=schema)
_column = None
if colname is None:
# colname is None in the case that ForeignKey argument
# was specified as table name only, in which case we
# match the column name to the same column on the
# parent.
key = self.parent
_column = table.c.get(self.parent.key, None)
elif self.link_to_name:
key = colname
for c in table.c:
if c.name == colname:
_column = c
else:
key = colname
_column = table.c.get(colname, None)
if _column is None:
raise exc.NoReferencedColumnError(
"Could not create ForeignKey '%s' on table '%s': "
"table '%s' has no column named '%s'" % (
self._colspec, parenttable.name, table.name, key),
table.name, key)
elif hasattr(self._colspec, '__clause_element__'):
_column = self._colspec.__clause_element__()
else:
_column = self._colspec
# propagate TypeEngine to parent if it didn't have one
if isinstance(self.parent.type, sqltypes.NullType):
self.parent.type = _column.type
return _column
def _set_parent(self, column):
if hasattr(self, 'parent'):
if self.parent is column:
return
raise exc.InvalidRequestError(
"This ForeignKey already has a parent !")
self.parent = column
self.parent.foreign_keys.add(self)
self.parent._on_table_attach(self._set_table)
def _set_table(self, column, table):
# standalone ForeignKey - create ForeignKeyConstraint
# on the hosting Table when attached to the Table.
if self.constraint is None and isinstance(table, Table):
self.constraint = ForeignKeyConstraint(
[], [], use_alter=self.use_alter, name=self.name,
onupdate=self.onupdate, ondelete=self.ondelete,
deferrable=self.deferrable, initially=self.initially,
)
self.constraint._elements[self.parent] = self
self.constraint._set_parent_with_dispatch(table)
table.foreign_keys.add(self)
class _NotAColumnExpr(object):
def _not_a_column_expr(self):
raise exc.InvalidRequestError(
"This %s cannot be used directly "
"as a column expression." % self.__class__.__name__)
__clause_element__ = self_group = lambda self: self._not_a_column_expr()
_from_objects = property(lambda self: self._not_a_column_expr())
class DefaultGenerator(_NotAColumnExpr, SchemaItem):
"""Base class for column *default* values."""
__visit_name__ = 'default_generator'
is_sequence = False
is_server_default = False
column = None
def __init__(self, for_update=False):
self.for_update = for_update
def _set_parent(self, column):
self.column = column
if self.for_update:
self.column.onupdate = self
else:
self.column.default = self
def execute(self, bind=None, **kwargs):
if bind is None:
bind = _bind_or_error(self)
return bind._execute_default(self, **kwargs)
@property
def bind(self):
"""Return the connectable associated with this default."""
if getattr(self, 'column', None) is not None:
return self.column.table.bind
else:
return None
def __repr__(self):
return "DefaultGenerator()"
class ColumnDefault(DefaultGenerator):
"""A plain default value on a column.
This could correspond to a constant, a callable function,
or a SQL clause.
:class:`.ColumnDefault` is generated automatically
whenever the ``default``, ``onupdate`` arguments of
:class:`.Column` are used. A :class:`.ColumnDefault`
can be passed positionally as well.
For example, the following::
Column('foo', Integer, default=50)
Is equivalent to::
Column('foo', Integer, ColumnDefault(50))
"""
def __init__(self, arg, **kwargs):
super(ColumnDefault, self).__init__(**kwargs)
if isinstance(arg, FetchedValue):
raise exc.ArgumentError(
"ColumnDefault may not be a server-side default type.")
if util.callable(arg):
arg = self._maybe_wrap_callable(arg)
self.arg = arg
@util.memoized_property
def is_callable(self):
return util.callable(self.arg)
@util.memoized_property
def is_clause_element(self):
return isinstance(self.arg, expression.ClauseElement)
@util.memoized_property
def is_scalar(self):
return not self.is_callable and \
not self.is_clause_element and \
not self.is_sequence
def _maybe_wrap_callable(self, fn):
"""Backward compat: Wrap callables that don't accept a context."""
if inspect.isfunction(fn):
inspectable = fn
elif inspect.isclass(fn):
inspectable = fn.__init__
elif hasattr(fn, '__call__'):
inspectable = fn.__call__
else:
# probably not inspectable, try anyways.
inspectable = fn
try:
argspec = inspect.getargspec(inspectable)
except TypeError:
return lambda ctx: fn()
positionals = len(argspec[0])
# Py3K compat - no unbound methods
if inspect.ismethod(inspectable) or inspect.isclass(fn):
positionals -= 1
if positionals == 0:
return lambda ctx: fn()
defaulted = argspec[3] is not None and len(argspec[3]) or 0
if positionals - defaulted > 1:
raise exc.ArgumentError(
"ColumnDefault Python function takes zero or one "
"positional arguments")
return fn
def _visit_name(self):
if self.for_update:
return "column_onupdate"
else:
return "column_default"
__visit_name__ = property(_visit_name)
def __repr__(self):
return "ColumnDefault(%r)" % self.arg
class Sequence(DefaultGenerator):
"""Represents a named database sequence.
The :class:`.Sequence` object represents the name and configurational
parameters of a database sequence. It also represents
a construct that can be "executed" by a SQLAlchemy :class:`.Engine`
or :class:`.Connection`, rendering the appropriate "next value" function
for the target database and returning a result.
The :class:`.Sequence` is typically associated with a primary key column::
some_table = Table('some_table', metadata,
Column('id', Integer, Sequence('some_table_seq'), primary_key=True)
)
When CREATE TABLE is emitted for the above :class:`.Table`, if the
target platform supports sequences, a CREATE SEQUENCE statement will
be emitted as well. For platforms that don't support sequences,
the :class:`.Sequence` construct is ignored.
See also: :class:`.CreateSequence` :class:`.DropSequence`
"""
__visit_name__ = 'sequence'
is_sequence = True
def __init__(self, name, start=None, increment=None, schema=None,
optional=False, quote=None, metadata=None,
for_update=False):
"""Construct a :class:`.Sequence` object.
:param name: The name of the sequence.
:param start: the starting index of the sequence. This value is
used when the CREATE SEQUENCE command is emitted to the database
as the value of the "START WITH" clause. If ``None``, the
clause is omitted, which on most platforms indicates a starting
value of 1.
:param increment: the increment value of the sequence. This
value is used when the CREATE SEQUENCE command is emitted to
the database as the value of the "INCREMENT BY" clause. If ``None``,
the clause is omitted, which on most platforms indicates an
increment of 1.
:param schema: Optional schema name for the sequence, if located
in a schema other than the default.
:param optional: boolean value, when ``True``, indicates that this
:class:`.Sequence` object only needs to be explicitly generated
on backends that don't provide another way to generate primary
key identifiers. Currently, it essentially means, "don't create
this sequence on the Postgresql backend, where the SERIAL keyword
creates a sequence for us automatically".
:param quote: boolean value, when ``True`` or ``False``, explicitly
forces quoting of the schema name on or off. When left at its
default of ``None``, normal quoting rules based on casing and reserved
words take place.
:param metadata: optional :class:`.MetaData` object which will be
associated with this :class:`.Sequence`. A :class:`.Sequence`
that is associated with a :class:`.MetaData` gains access to the
``bind`` of that :class:`.MetaData`, meaning the :meth:`.Sequence.create`
and :meth:`.Sequence.drop` methods will make usage of that engine
automatically. Additionally, the appropriate CREATE SEQUENCE/
DROP SEQUENCE DDL commands will be emitted corresponding to this
:class:`.Sequence` when :meth:`.MetaData.create_all` and
:meth:`.MetaData.drop_all` are invoked (new in 0.7).
Note that when a :class:`.Sequence` is applied to a :class:`.Column`,
the :class:`.Sequence` is automatically associated with the
:class:`.MetaData` object of that column's parent :class:`.Table`,
when that association is made. The :class:`.Sequence` will then
be subject to automatic CREATE SEQUENCE/DROP SEQUENCE corresponding
to when the :class:`.Table` object itself is created or dropped,
rather than that of the :class:`.MetaData` object overall.
:param for_update: Indicates this :class:`.Sequence`, when associated
with a :class:`.Column`, should be invoked for UPDATE statements
on that column's table, rather than for INSERT statements, when
no value is otherwise present for that column in the statement.
"""
super(Sequence, self).__init__(for_update=for_update)
self.name = name
self.start = start
self.increment = increment
self.optional = optional
self.quote = quote
self.schema = schema
self.metadata = metadata
self._key = _get_table_key(name, schema)
if metadata:
self._set_metadata(metadata)
@util.memoized_property
def is_callable(self):
return False
@util.memoized_property
def is_clause_element(self):
return False
def next_value(self):
"""Return a :class:`.next_value` function element
which will render the appropriate increment function
for this :class:`.Sequence` within any SQL expression.
"""
return expression.func.next_value(self, bind=self.bind)
def __repr__(self):
return "Sequence(%s)" % ', '.join(
[repr(self.name)] +
["%s=%s" % (k, repr(getattr(self, k)))
for k in ['start', 'increment', 'optional']])
def _set_parent(self, column):
super(Sequence, self)._set_parent(column)
column._on_table_attach(self._set_table)
def _set_table(self, column, table):
self._set_metadata(table.metadata)
def _set_metadata(self, metadata):
self.metadata = metadata
self.metadata._sequences[self._key] = self
@property
def bind(self):
if self.metadata:
return self.metadata.bind
else:
return None
def create(self, bind=None, checkfirst=True):
"""Creates this sequence in the database."""
if bind is None:
bind = _bind_or_error(self)
bind.create(self, checkfirst=checkfirst)
def drop(self, bind=None, checkfirst=True):
"""Drops this sequence from the database."""
if bind is None:
bind = _bind_or_error(self)
bind.drop(self, checkfirst=checkfirst)
def _not_a_column_expr(self):
raise exc.InvalidRequestError(
"This %s cannot be used directly "
"as a column expression. Use func.next_value(sequence) "
"to produce a 'next value' function that's usable "
"as a column element."
% self.__class__.__name__)
class FetchedValue(_NotAColumnExpr, events.SchemaEventTarget):
"""A marker for a transparent database-side default.
Use :class:`.FetchedValue` when the database is configured
to provide some automatic default for a column.
E.g.::
Column('foo', Integer, FetchedValue())
Would indicate that some trigger or default generator
will create a new value for the ``foo`` column during an
INSERT.
"""
is_server_default = True
reflected = False
has_argument = False
def __init__(self, for_update=False):
self.for_update = for_update
def _set_parent(self, column):
self.column = column
if self.for_update:
self.column.server_onupdate = self
else:
self.column.server_default = self
def __repr__(self):
return 'FetchedValue(for_update=%r)' % self.for_update
class DefaultClause(FetchedValue):
"""A DDL-specified DEFAULT column value.
:class:`.DefaultClause` is a :class:`.FetchedValue`
that also generates a "DEFAULT" clause when
"CREATE TABLE" is emitted.
:class:`.DefaultClause` is generated automatically
whenever the ``server_default``, ``server_onupdate`` arguments of
:class:`.Column` are used. A :class:`.DefaultClause`
can be passed positionally as well.
For example, the following::
Column('foo', Integer, server_default="50")
Is equivalent to::
Column('foo', Integer, DefaultClause("50"))
"""
has_argument = True
def __init__(self, arg, for_update=False, _reflected=False):
util.assert_arg_type(arg, (basestring,
expression.ClauseElement,
expression._TextClause), 'arg')
super(DefaultClause, self).__init__(for_update)
self.arg = arg
self.reflected = _reflected
def __repr__(self):
return "DefaultClause(%r, for_update=%r)" % \
(self.arg, self.for_update)
class PassiveDefault(DefaultClause):
"""A DDL-specified DEFAULT column value.
.. deprecated:: 0.6 :class:`.PassiveDefault` is deprecated.
Use :class:`.DefaultClause`.
"""
@util.deprecated("0.6",
":class:`.PassiveDefault` is deprecated. "
"Use :class:`.DefaultClause`.",
False)
def __init__(self, *arg, **kw):
DefaultClause.__init__(self, *arg, **kw)
class Constraint(SchemaItem):
"""A table-level SQL constraint."""
__visit_name__ = 'constraint'
def __init__(self, name=None, deferrable=None, initially=None,
_create_rule=None):
"""Create a SQL constraint.
:param name:
Optional, the in-database name of this ``Constraint``.
:param deferrable:
Optional bool. If set, emit DEFERRABLE or NOT DEFERRABLE when
issuing DDL for this constraint.
:param initially:
Optional string. If set, emit INITIALLY <value> when issuing DDL
for this constraint.
:param _create_rule:
a callable which is passed the DDLCompiler object during
compilation. Returns True or False to signal inline generation of
this Constraint.
The AddConstraint and DropConstraint DDL constructs provide
DDLElement's more comprehensive "conditional DDL" approach that is
passed a database connection when DDL is being issued. _create_rule
is instead called during any CREATE TABLE compilation, where there
may not be any transaction/connection in progress. However, it
allows conditional compilation of the constraint even for backends
which do not support addition of constraints through ALTER TABLE,
which currently includes SQLite.
_create_rule is used by some types to create constraints.
Currently, its call signature is subject to change at any time.
"""
self.name = name
self.deferrable = deferrable
self.initially = initially
self._create_rule = _create_rule
util.set_creation_order(self)
@property
def table(self):
try:
if isinstance(self.parent, Table):
return self.parent
except AttributeError:
pass
raise exc.InvalidRequestError(
"This constraint is not bound to a table. Did you "
"mean to call table.add_constraint(constraint) ?")
def _set_parent(self, parent):
self.parent = parent
parent.constraints.add(self)
def copy(self, **kw):
raise NotImplementedError()
class ColumnCollectionMixin(object):
def __init__(self, *columns):
self.columns = expression.ColumnCollection()
self._pending_colargs = [_to_schema_column_or_string(c)
for c in columns]
if self._pending_colargs and \
isinstance(self._pending_colargs[0], Column) and \
self._pending_colargs[0].table is not None:
self._set_parent_with_dispatch(self._pending_colargs[0].table)
def _set_parent(self, table):
for col in self._pending_colargs:
if isinstance(col, basestring):
col = table.c[col]
self.columns.add(col)
class ColumnCollectionConstraint(ColumnCollectionMixin, Constraint):
"""A constraint that proxies a ColumnCollection."""
def __init__(self, *columns, **kw):
"""
:param \*columns:
A sequence of column names or Column objects.
:param name:
Optional, the in-database name of this constraint.
:param deferrable:
Optional bool. If set, emit DEFERRABLE or NOT DEFERRABLE when
issuing DDL for this constraint.
:param initially:
Optional string. If set, emit INITIALLY <value> when issuing DDL
for this constraint.
"""
ColumnCollectionMixin.__init__(self, *columns)
Constraint.__init__(self, **kw)
def _set_parent(self, table):
ColumnCollectionMixin._set_parent(self, table)
Constraint._set_parent(self, table)
def __contains__(self, x):
return x in self.columns
def copy(self, **kw):
c = self.__class__(name=self.name, deferrable=self.deferrable,
initially=self.initially, *self.columns.keys())
c.dispatch._update(self.dispatch)
return c
def contains_column(self, col):
return self.columns.contains_column(col)
def __iter__(self):
# inlining of
# return iter(self.columns)
# ColumnCollection->OrderedProperties->OrderedDict
ordered_dict = self.columns._data
return (ordered_dict[key] for key in ordered_dict._list)
def __len__(self):
return len(self.columns._data)
class CheckConstraint(Constraint):
"""A table- or column-level CHECK constraint.
Can be included in the definition of a Table or Column.
"""
def __init__(self, sqltext, name=None, deferrable=None,
initially=None, table=None, _create_rule=None):
"""Construct a CHECK constraint.
:param sqltext:
A string containing the constraint definition, which will be used
verbatim, or a SQL expression construct.
:param name:
Optional, the in-database name of the constraint.
:param deferrable:
Optional bool. If set, emit DEFERRABLE or NOT DEFERRABLE when
issuing DDL for this constraint.
:param initially:
Optional string. If set, emit INITIALLY <value> when issuing DDL
for this constraint.
"""
super(CheckConstraint, self).\
__init__(name, deferrable, initially, _create_rule)
self.sqltext = expression._literal_as_text(sqltext)
if table is not None:
self._set_parent_with_dispatch(table)
def __visit_name__(self):
if isinstance(self.parent, Table):
return "check_constraint"
else:
return "column_check_constraint"
__visit_name__ = property(__visit_name__)
def copy(self, **kw):
c = CheckConstraint(self.sqltext,
name=self.name,
initially=self.initially,
deferrable=self.deferrable,
_create_rule=self._create_rule)
c.dispatch._update(self.dispatch)
return c
class ForeignKeyConstraint(Constraint):
"""A table-level FOREIGN KEY constraint.
Defines a single column or composite FOREIGN KEY ... REFERENCES
constraint. For a no-frills, single column foreign key, adding a
:class:`.ForeignKey` to the definition of a :class:`.Column` is a shorthand
equivalent for an unnamed, single column :class:`.ForeignKeyConstraint`.
Examples of foreign key configuration are in :ref:`metadata_foreignkeys`.
"""
__visit_name__ = 'foreign_key_constraint'
def __init__(self, columns, refcolumns, name=None, onupdate=None,
ondelete=None, deferrable=None, initially=None, use_alter=False,
link_to_name=False, table=None):
"""Construct a composite-capable FOREIGN KEY.
:param columns: A sequence of local column names. The named columns
must be defined and present in the parent Table. The names should
match the ``key`` given to each column (defaults to the name) unless
``link_to_name`` is True.
:param refcolumns: A sequence of foreign column names or Column
objects. The columns must all be located within the same Table.
:param name: Optional, the in-database name of the key.
:param onupdate: Optional string. If set, emit ON UPDATE <value> when
issuing DDL for this constraint. Typical values include CASCADE,
DELETE and RESTRICT.
:param ondelete: Optional string. If set, emit ON DELETE <value> when
issuing DDL for this constraint. Typical values include CASCADE,
DELETE and RESTRICT.
:param deferrable: Optional bool. If set, emit DEFERRABLE or NOT
DEFERRABLE when issuing DDL for this constraint.
:param initially: Optional string. If set, emit INITIALLY <value> when
issuing DDL for this constraint.
:param link_to_name: if True, the string name given in ``column`` is
the rendered name of the referenced column, not its locally assigned
``key``.
:param use_alter: If True, do not emit the DDL for this constraint as
part of the CREATE TABLE definition. Instead, generate it via an
ALTER TABLE statement issued after the full collection of tables
have been created, and drop it via an ALTER TABLE statement before
the full collection of tables are dropped. This is shorthand for the
usage of :class:`.AddConstraint` and :class:`.DropConstraint` applied
as "after-create" and "before-drop" events on the MetaData object.
This is normally used to generate/drop constraints on objects that
are mutually dependent on each other.
"""
super(ForeignKeyConstraint, self).\
__init__(name, deferrable, initially)
self.onupdate = onupdate
self.ondelete = ondelete
self.link_to_name = link_to_name
if self.name is None and use_alter:
raise exc.ArgumentError("Alterable Constraint requires a name")
self.use_alter = use_alter
self._elements = util.OrderedDict()
# standalone ForeignKeyConstraint - create
# associated ForeignKey objects which will be applied to hosted
# Column objects (in col.foreign_keys), either now or when attached
# to the Table for string-specified names
for col, refcol in zip(columns, refcolumns):
self._elements[col] = ForeignKey(
refcol,
_constraint=self,
name=self.name,
onupdate=self.onupdate,
ondelete=self.ondelete,
use_alter=self.use_alter,
link_to_name=self.link_to_name
)
if table is not None:
self._set_parent_with_dispatch(table)
@property
def columns(self):
return self._elements.keys()
@property
def elements(self):
return self._elements.values()
def _set_parent(self, table):
super(ForeignKeyConstraint, self)._set_parent(table)
for col, fk in self._elements.iteritems():
# string-specified column names now get
# resolved to Column objects
if isinstance(col, basestring):
col = table.c[col]
if not hasattr(fk, 'parent') or \
fk.parent is not col:
fk._set_parent_with_dispatch(col)
if self.use_alter:
def supports_alter(ddl, event, schema_item, bind, **kw):
return table in set(kw['tables']) and \
bind.dialect.supports_alter
event.listen(table.metadata, "after_create", AddConstraint(self, on=supports_alter))
event.listen(table.metadata, "before_drop", DropConstraint(self, on=supports_alter))
def copy(self, **kw):
fkc = ForeignKeyConstraint(
[x.parent.name for x in self._elements.values()],
[x._get_colspec(**kw) for x in self._elements.values()],
name=self.name,
onupdate=self.onupdate,
ondelete=self.ondelete,
use_alter=self.use_alter,
deferrable=self.deferrable,
initially=self.initially,
link_to_name=self.link_to_name
)
fkc.dispatch._update(self.dispatch)
return fkc
class PrimaryKeyConstraint(ColumnCollectionConstraint):
"""A table-level PRIMARY KEY constraint.
Defines a single column or composite PRIMARY KEY constraint. For a
no-frills primary key, adding ``primary_key=True`` to one or more
``Column`` definitions is a shorthand equivalent for an unnamed single- or
multiple-column PrimaryKeyConstraint.
"""
__visit_name__ = 'primary_key_constraint'
def _set_parent(self, table):
super(PrimaryKeyConstraint, self)._set_parent(table)
if table.primary_key in table.constraints:
table.constraints.remove(table.primary_key)
table.primary_key = self
table.constraints.add(self)
for c in self.columns:
c.primary_key = True
def _replace(self, col):
self.columns.replace(col)
class UniqueConstraint(ColumnCollectionConstraint):
"""A table-level UNIQUE constraint.
Defines a single column or composite UNIQUE constraint. For a no-frills,
single column constraint, adding ``unique=True`` to the ``Column``
definition is a shorthand equivalent for an unnamed, single column
UniqueConstraint.
"""
__visit_name__ = 'unique_constraint'
class Index(ColumnCollectionMixin, SchemaItem):
"""A table-level INDEX.
Defines a composite (one or more column) INDEX. For a no-frills, single
column index, adding ``index=True`` to the ``Column`` definition is
a shorthand equivalent for an unnamed, single column Index.
"""
__visit_name__ = 'index'
def __init__(self, name, *columns, **kw):
"""Construct an index object.
:param name:
The name of the index
:param \*columns:
Columns to include in the index. All columns must belong to the same
table.
:param unique:
Defaults to False: create a unique index.
:param \**kw:
Other keyword arguments may be interpreted by specific dialects.
"""
self.table = None
# will call _set_parent() if table-bound column
# objects are present
ColumnCollectionMixin.__init__(self, *columns)
self.name = name
self.unique = kw.pop('unique', False)
self.kwargs = kw
def _set_parent(self, table):
ColumnCollectionMixin._set_parent(self, table)
if self.table is not None and table is not self.table:
raise exc.ArgumentError(
"Index '%s' is against table '%s', and "
"cannot be associated with table '%s'." % (
self.name,
self.table.description,
table.description
)
)
self.table = table
for c in self.columns:
if c.table != self.table:
raise exc.ArgumentError(
"Column '%s' is not part of table '%s'." %
(c, self.table.description)
)
table.indexes.add(self)
@property
def bind(self):
"""Return the connectable associated with this Index."""
return self.table.bind
def create(self, bind=None):
if bind is None:
bind = _bind_or_error(self)
bind.create(self)
return self
def drop(self, bind=None):
if bind is None:
bind = _bind_or_error(self)
bind.drop(self)
def __repr__(self):
return 'Index("%s", %s%s)' % (
self.name,
', '.join(repr(c) for c in self.columns),
(self.unique and ', unique=True') or '')
class MetaData(SchemaItem):
"""A collection of Tables and their associated schema constructs.
Holds a collection of Tables and an optional binding to an ``Engine`` or
``Connection``. If bound, the :class:`~sqlalchemy.schema.Table` objects
in the collection and their columns may participate in implicit SQL
execution.
The `Table` objects themselves are stored in the `metadata.tables`
dictionary.
The ``bind`` property may be assigned to dynamically. A common pattern is
to start unbound and then bind later when an engine is available::
metadata = MetaData()
# define tables
Table('mytable', metadata, ...)
# connect to an engine later, perhaps after loading a URL from a
# configuration file
metadata.bind = an_engine
MetaData is a thread-safe object after tables have been explicitly defined
or loaded via reflection.
.. index::
single: thread safety; MetaData
"""
__visit_name__ = 'metadata'
def __init__(self, bind=None, reflect=False):
"""Create a new MetaData object.
:param bind:
An Engine or Connection to bind to. May also be a string or URL
instance, these are passed to create_engine() and this MetaData will
be bound to the resulting engine.
:param reflect:
Optional, automatically load all tables from the bound database.
Defaults to False. ``bind`` is required when this option is set.
For finer control over loaded tables, use the ``reflect`` method of
``MetaData``.
"""
self.tables = util.immutabledict()
self._schemas = set()
self._sequences = {}
self.bind = bind
if reflect:
if not bind:
raise exc.ArgumentError(
"A bind must be supplied in conjunction "
"with reflect=True")
self.reflect()
def __repr__(self):
return 'MetaData(%r)' % self.bind
def __contains__(self, table_or_key):
if not isinstance(table_or_key, basestring):
table_or_key = table_or_key.key
return table_or_key in self.tables
def _add_table(self, name, schema, table):
key = _get_table_key(name, schema)
dict.__setitem__(self.tables, key, table)
if schema:
self._schemas.add(schema)
def _remove_table(self, name, schema):
key = _get_table_key(name, schema)
dict.pop(self.tables, key, None)
if self._schemas:
self._schemas = set([t.schema
for t in self.tables.values()
if t.schema is not None])
def __getstate__(self):
return {'tables': self.tables, 'schemas':self._schemas,
'sequences':self._sequences}
def __setstate__(self, state):
self.tables = state['tables']
self._bind = None
self._sequences = state['sequences']
self._schemas = state['schemas']
def is_bound(self):
"""True if this MetaData is bound to an Engine or Connection."""
return self._bind is not None
def bind(self):
"""An Engine or Connection to which this MetaData is bound.
This property may be assigned an ``Engine`` or ``Connection``, or
assigned a string or URL to automatically create a basic ``Engine``
for this bind with ``create_engine()``.
"""
return self._bind
def _bind_to(self, bind):
"""Bind this MetaData to an Engine, Connection, string or URL."""
if isinstance(bind, (basestring, url.URL)):
from sqlalchemy import create_engine
self._bind = create_engine(bind)
else:
self._bind = bind
bind = property(bind, _bind_to)
def clear(self):
"""Clear all Table objects from this MetaData."""
dict.clear(self.tables)
self._schemas.clear()
def remove(self, table):
"""Remove the given Table object from this MetaData."""
self._remove_table(table.name, table.schema)
@property
def sorted_tables(self):
"""Returns a list of ``Table`` objects sorted in order of
dependency.
"""
return sqlutil.sort_tables(self.tables.itervalues())
def reflect(self, bind=None, schema=None, views=False, only=None):
"""Load all available table definitions from the database.
Automatically creates ``Table`` entries in this ``MetaData`` for any
table available in the database but not yet present in the
``MetaData``. May be called multiple times to pick up tables recently
added to the database, however no special action is taken if a table
in this ``MetaData`` no longer exists in the database.
:param bind:
A :class:`~sqlalchemy.engine.base.Connectable` used to access the
database; if None, uses the existing bind on this ``MetaData``, if
any.
:param schema:
Optional, query and reflect tables from an alterate schema.
:param views:
If True, also reflect views.
:param only:
Optional. Load only a sub-set of available named tables. May be
specified as a sequence of names or a callable.
If a sequence of names is provided, only those tables will be
reflected. An error is raised if a table is requested but not
available. Named tables already present in this ``MetaData`` are
ignored.
If a callable is provided, it will be used as a boolean predicate to
filter the list of potential table names. The callable is called
with a table name and this ``MetaData`` instance as positional
arguments and should return a true value for any table to reflect.
"""
reflect_opts = {'autoload': True}
if bind is None:
bind = _bind_or_error(self)
conn = None
else:
reflect_opts['autoload_with'] = bind
conn = bind.contextual_connect()
if schema is not None:
reflect_opts['schema'] = schema
try:
available = util.OrderedSet(bind.engine.table_names(schema,
connection=conn))
if views:
available.update(
bind.dialect.get_view_names(conn or bind, schema)
)
current = set(self.tables.iterkeys())
if only is None:
load = [name for name in available if name not in current]
elif util.callable(only):
load = [name for name in available
if name not in current and only(name, self)]
else:
missing = [name for name in only if name not in available]
if missing:
s = schema and (" schema '%s'" % schema) or ''
raise exc.InvalidRequestError(
'Could not reflect: requested table(s) not available '
'in %s%s: (%s)' %
(bind.engine.url, s, ', '.join(missing)))
load = [name for name in only if name not in current]
for name in load:
Table(name, self, **reflect_opts)
finally:
if conn is not None:
conn.close()
def append_ddl_listener(self, event_name, listener):
"""Append a DDL event listener to this ``MetaData``.
Deprecated. See :class:`.DDLEvents`.
"""
def adapt_listener(target, connection, **kw):
listener(event, target, connection, **kw)
event.listen(self, "" + event_name.replace('-', '_'), adapt_listener)
def create_all(self, bind=None, tables=None, checkfirst=True):
"""Create all tables stored in this metadata.
Conditional by default, will not attempt to recreate tables already
present in the target database.
:param bind:
A :class:`~sqlalchemy.engine.base.Connectable` used to access the
database; if None, uses the existing bind on this ``MetaData``, if
any.
:param tables:
Optional list of ``Table`` objects, which is a subset of the total
tables in the ``MetaData`` (others are ignored).
:param checkfirst:
Defaults to True, don't issue CREATEs for tables already present
in the target database.
"""
if bind is None:
bind = _bind_or_error(self)
bind.create(self, checkfirst=checkfirst, tables=tables)
def drop_all(self, bind=None, tables=None, checkfirst=True):
"""Drop all tables stored in this metadata.
Conditional by default, will not attempt to drop tables not present in
the target database.
:param bind:
A :class:`~sqlalchemy.engine.base.Connectable` used to access the
database; if None, uses the existing bind on this ``MetaData``, if
any.
:param tables:
Optional list of ``Table`` objects, which is a subset of the
total tables in the ``MetaData`` (others are ignored).
:param checkfirst:
Defaults to True, only issue DROPs for tables confirmed to be
present in the target database.
"""
if bind is None:
bind = _bind_or_error(self)
bind.drop(self, checkfirst=checkfirst, tables=tables)
class ThreadLocalMetaData(MetaData):
"""A MetaData variant that presents a different ``bind`` in every thread.
Makes the ``bind`` property of the MetaData a thread-local value, allowing
this collection of tables to be bound to different ``Engine``
implementations or connections in each thread.
The ThreadLocalMetaData starts off bound to None in each thread. Binds
must be made explicitly by assigning to the ``bind`` property or using
``connect()``. You can also re-bind dynamically multiple times per
thread, just like a regular ``MetaData``.
"""
__visit_name__ = 'metadata'
def __init__(self):
"""Construct a ThreadLocalMetaData."""
self.context = util.threading.local()
self.__engines = {}
super(ThreadLocalMetaData, self).__init__()
def bind(self):
"""The bound Engine or Connection for this thread.
This property may be assigned an Engine or Connection, or assigned a
string or URL to automatically create a basic Engine for this bind
with ``create_engine()``."""
return getattr(self.context, '_engine', None)
def _bind_to(self, bind):
"""Bind to a Connectable in the caller's thread."""
if isinstance(bind, (basestring, url.URL)):
try:
self.context._engine = self.__engines[bind]
except KeyError:
from sqlalchemy import create_engine
e = create_engine(bind)
self.__engines[bind] = e
self.context._engine = e
else:
# TODO: this is squirrely. we shouldnt have to hold onto engines
# in a case like this
if bind not in self.__engines:
self.__engines[bind] = bind
self.context._engine = bind
bind = property(bind, _bind_to)
def is_bound(self):
"""True if there is a bind for this thread."""
return (hasattr(self.context, '_engine') and
self.context._engine is not None)
def dispose(self):
"""Dispose all bound engines, in all thread contexts."""
for e in self.__engines.itervalues():
if hasattr(e, 'dispose'):
e.dispose()
class SchemaVisitor(visitors.ClauseVisitor):
"""Define the visiting for ``SchemaItem`` objects."""
__traverse_options__ = {'schema_visitor':True}
class DDLElement(expression.Executable, expression.ClauseElement):
"""Base class for DDL expression constructs.
This class is the base for the general purpose :class:`.DDL` class,
as well as the various create/drop clause constructs such as
:class:`.CreateTable`, :class:`.DropTable`, :class:`.AddConstraint`,
etc.
:class:`.DDLElement` integrates closely with SQLAlchemy events,
introduced in :ref:`event_toplevel`. An instance of one is
itself an event receiving callable::
event.listen(
users,
'after_create',
AddConstraint(constraint).execute_if(dialect='postgresql')
)
See also:
:class:`.DDL`
:class:`.DDLEvents`
:ref:`event_toplevel`
:ref:`schema_ddl_sequences`
"""
_execution_options = expression.Executable.\
_execution_options.union({'autocommit':True})
target = None
on = None
dialect = None
callable_ = None
def execute(self, bind=None, target=None):
"""Execute this DDL immediately.
Executes the DDL statement in isolation using the supplied
:class:`~sqlalchemy.engine.base.Connectable` or
:class:`~sqlalchemy.engine.base.Connectable` assigned to the ``.bind``
property, if not supplied. If the DDL has a conditional ``on``
criteria, it will be invoked with None as the event.
:param bind:
Optional, an ``Engine`` or ``Connection``. If not supplied, a valid
:class:`~sqlalchemy.engine.base.Connectable` must be present in the
``.bind`` property.
:param target:
Optional, defaults to None. The target SchemaItem for the
execute call. Will be passed to the ``on`` callable if any,
and may also provide string expansion data for the
statement. See ``execute_at`` for more information.
"""
if bind is None:
bind = _bind_or_error(self)
if self._should_execute(target, bind):
return bind.execute(self.against(target))
else:
bind.engine.logger.info(
"DDL execution skipped, criteria not met.")
@util.deprecated("0.7", "See :class:`.DDLEvents`, as well as "
":meth:`.DDLElement.execute_if`.")
def execute_at(self, event_name, target):
"""Link execution of this DDL to the DDL lifecycle of a SchemaItem.
Links this ``DDLElement`` to a ``Table`` or ``MetaData`` instance,
executing it when that schema item is created or dropped. The DDL
statement will be executed using the same Connection and transactional
context as the Table create/drop itself. The ``.bind`` property of
this statement is ignored.
:param event:
One of the events defined in the schema item's ``.ddl_events``;
e.g. 'before-create', 'after-create', 'before-drop' or 'after-drop'
:param target:
The Table or MetaData instance for which this DDLElement will
be associated with.
A DDLElement instance can be linked to any number of schema items.
``execute_at`` builds on the ``append_ddl_listener`` interface of
:class:`.MetaData` and :class:`.Table` objects.
Caveat: Creating or dropping a Table in isolation will also trigger
any DDL set to ``execute_at`` that Table's MetaData. This may change
in a future release.
"""
def call_event(target, connection, **kw):
if self._should_execute_deprecated(event_name,
target, connection, **kw):
return connection.execute(self.against(target))
event.listen(target, "" + event_name.replace('-', '_'), call_event)
@expression._generative
def against(self, target):
"""Return a copy of this DDL against a specific schema item."""
self.target = target
@expression._generative
def execute_if(self, dialect=None, callable_=None, state=None):
"""Return a callable that will execute this
DDLElement conditionally.
Used to provide a wrapper for event listening::
event.listen(
metadata,
'before_create',
DDL("my_ddl").execute_if(dialect='postgresql')
)
:param dialect: May be a string, tuple or a callable
predicate. If a string, it will be compared to the name of the
executing database dialect::
DDL('something').execute_if(dialect='postgresql')
If a tuple, specifies multiple dialect names::
DDL('something').execute_if(dialect=('postgresql', 'mysql'))
:param callable_: A callable, which will be invoked with
four positional arguments as well as optional keyword
arguments:
:ddl:
This DDL element.
:target:
The :class:`.Table` or :class:`.MetaData` object which is the target of
this event. May be None if the DDL is executed explicitly.
:bind:
The :class:`.Connection` being used for DDL execution
:tables:
Optional keyword argument - a list of Table objects which are to
be created/ dropped within a MetaData.create_all() or drop_all()
method call.
:state:
Optional keyword argument - will be the ``state`` argument
passed to this function.
:checkfirst:
Keyword argument, will be True if the 'checkfirst' flag was
set during the call to ``create()``, ``create_all()``,
``drop()``, ``drop_all()``.
If the callable returns a true value, the DDL statement will be
executed.
:param state: any value which will be passed to the callable_
as the ``state`` keyword argument.
See also:
:class:`.DDLEvents`
:ref:`event_toplevel`
"""
self.dialect = dialect
self.callable_ = callable_
self.state = state
def _should_execute(self, target, bind, **kw):
if self.on is not None and \
not self._should_execute_deprecated(None, target, bind, **kw):
return False
if isinstance(self.dialect, basestring):
if self.dialect != bind.engine.name:
return False
elif isinstance(self.dialect, (tuple, list, set)):
if bind.engine.name not in self.dialect:
return False
if self.callable_ is not None and \
not self.callable_(self, target, bind, state=self.state, **kw):
return False
return True
def _should_execute_deprecated(self, event, target, bind, **kw):
if self.on is None:
return True
elif isinstance(self.on, basestring):
return self.on == bind.engine.name
elif isinstance(self.on, (tuple, list, set)):
return bind.engine.name in self.on
else:
return self.on(self, event, target, bind, **kw)
def __call__(self, target, bind, **kw):
"""Execute the DDL as a ddl_listener."""
if self._should_execute(target, bind, **kw):
return bind.execute(self.against(target))
def _check_ddl_on(self, on):
if (on is not None and
(not isinstance(on, (basestring, tuple, list, set)) and
not util.callable(on))):
raise exc.ArgumentError(
"Expected the name of a database dialect, a tuple "
"of names, or a callable for "
"'on' criteria, got type '%s'." % type(on).__name__)
def bind(self):
if self._bind:
return self._bind
def _set_bind(self, bind):
self._bind = bind
bind = property(bind, _set_bind)
def _generate(self):
s = self.__class__.__new__(self.__class__)
s.__dict__ = self.__dict__.copy()
return s
def _compiler(self, dialect, **kw):
"""Return a compiler appropriate for this ClauseElement, given a
Dialect."""
return dialect.ddl_compiler(dialect, self, **kw)
class DDL(DDLElement):
"""A literal DDL statement.
Specifies literal SQL DDL to be executed by the database. DDL objects
function as DDL event listeners, and can be subscribed to those events
listed in :class:`.DDLEvents`, using either :class:`.Table` or :class:`.MetaData`
objects as targets. Basic templating support allows a single DDL instance
to handle repetitive tasks for multiple tables.
Examples::
from sqlalchemy import event, DDL
tbl = Table('users', metadata, Column('uid', Integer))
event.listen(tbl, 'before_create', DDL('DROP TRIGGER users_trigger'))
spow = DDL('ALTER TABLE %(table)s SET secretpowers TRUE')
event.listen(tbl, 'after_create', spow.execute_if(dialect='somedb'))
drop_spow = DDL('ALTER TABLE users SET secretpowers FALSE')
connection.execute(drop_spow)
When operating on Table events, the following ``statement``
string substitions are available::
%(table)s - the Table name, with any required quoting applied
%(schema)s - the schema name, with any required quoting applied
%(fullname)s - the Table name including schema, quoted if needed
The DDL's "context", if any, will be combined with the standard
substutions noted above. Keys present in the context will override
the standard substitutions.
"""
__visit_name__ = "ddl"
def __init__(self, statement, on=None, context=None, bind=None):
"""Create a DDL statement.
:param statement:
A string or unicode string to be executed. Statements will be
processed with Python's string formatting operator. See the
``context`` argument and the ``execute_at`` method.
A literal '%' in a statement must be escaped as '%%'.
SQL bind parameters are not available in DDL statements.
:param on:
Deprecated. See :meth:`.DDLElement.execute_if`.
Optional filtering criteria. May be a string, tuple or a callable
predicate. If a string, it will be compared to the name of the
executing database dialect::
DDL('something', on='postgresql')
If a tuple, specifies multiple dialect names::
DDL('something', on=('postgresql', 'mysql'))
If a callable, it will be invoked with four positional arguments
as well as optional keyword arguments:
:ddl:
This DDL element.
:event:
The name of the event that has triggered this DDL, such as
'after-create' Will be None if the DDL is executed explicitly.
:target:
The ``Table`` or ``MetaData`` object which is the target of
this event. May be None if the DDL is executed explicitly.
:connection:
The ``Connection`` being used for DDL execution
:tables:
Optional keyword argument - a list of Table objects which are to
be created/ dropped within a MetaData.create_all() or drop_all()
method call.
If the callable returns a true value, the DDL statement will be
executed.
:param context:
Optional dictionary, defaults to None. These values will be
available for use in string substitutions on the DDL statement.
:param bind:
Optional. A :class:`~sqlalchemy.engine.base.Connectable`, used by
default when ``execute()`` is invoked without a bind argument.
See also:
:class:`.DDLEvents`
:mod:`sqlalchemy.event`
"""
if not isinstance(statement, basestring):
raise exc.ArgumentError(
"Expected a string or unicode SQL statement, got '%r'" %
statement)
self.statement = statement
self.context = context or {}
self._check_ddl_on(on)
self.on = on
self._bind = bind
def __repr__(self):
return '<%s@%s; %s>' % (
type(self).__name__, id(self),
', '.join([repr(self.statement)] +
['%s=%r' % (key, getattr(self, key))
for key in ('on', 'context')
if getattr(self, key)]))
def _to_schema_column(element):
if hasattr(element, '__clause_element__'):
element = element.__clause_element__()
if not isinstance(element, Column):
raise exc.ArgumentError("schema.Column object expected")
return element
def _to_schema_column_or_string(element):
if hasattr(element, '__clause_element__'):
element = element.__clause_element__()
return element
class _CreateDropBase(DDLElement):
"""Base class for DDL constucts that represent CREATE and DROP or
equivalents.
The common theme of _CreateDropBase is a single
``element`` attribute which refers to the element
to be created or dropped.
"""
def __init__(self, element, on=None, bind=None):
self.element = element
self._check_ddl_on(on)
self.on = on
self.bind = bind
def _create_rule_disable(self, compiler):
"""Allow disable of _create_rule using a callable.
Pass to _create_rule using
util.portable_instancemethod(self._create_rule_disable)
to retain serializability.
"""
return False
class CreateTable(_CreateDropBase):
"""Represent a CREATE TABLE statement."""
__visit_name__ = "create_table"
class DropTable(_CreateDropBase):
"""Represent a DROP TABLE statement."""
__visit_name__ = "drop_table"
class CreateSequence(_CreateDropBase):
"""Represent a CREATE SEQUENCE statement."""
__visit_name__ = "create_sequence"
class DropSequence(_CreateDropBase):
"""Represent a DROP SEQUENCE statement."""
__visit_name__ = "drop_sequence"
class CreateIndex(_CreateDropBase):
"""Represent a CREATE INDEX statement."""
__visit_name__ = "create_index"
class DropIndex(_CreateDropBase):
"""Represent a DROP INDEX statement."""
__visit_name__ = "drop_index"
class AddConstraint(_CreateDropBase):
"""Represent an ALTER TABLE ADD CONSTRAINT statement."""
__visit_name__ = "add_constraint"
def __init__(self, element, *args, **kw):
super(AddConstraint, self).__init__(element, *args, **kw)
element._create_rule = util.portable_instancemethod(
self._create_rule_disable)
class DropConstraint(_CreateDropBase):
"""Represent an ALTER TABLE DROP CONSTRAINT statement."""
__visit_name__ = "drop_constraint"
def __init__(self, element, cascade=False, **kw):
self.cascade = cascade
super(DropConstraint, self).__init__(element, **kw)
element._create_rule = util.portable_instancemethod(
self._create_rule_disable)
def _bind_or_error(schemaitem, msg=None):
bind = schemaitem.bind
if not bind:
name = schemaitem.__class__.__name__
label = getattr(schemaitem, 'fullname',
getattr(schemaitem, 'name', None))
if label:
item = '%s %r' % (name, label)
else:
item = name
if isinstance(schemaitem, (MetaData, DDL)):
bindable = "the %s's .bind" % name
else:
bindable = "this %s's .metadata.bind" % name
if msg is None:
msg = "The %s is not bound to an Engine or Connection. "\
"Execution can not proceed without a database to execute "\
"against. Either execute with an explicit connection or "\
"assign %s to enable implicit execution." % \
(item, bindable)
raise exc.UnboundExecutionError(msg)
return bind
|