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"""
Database schema version management.
"""
import sys
import logging
from sqlalchemy import (Table, Column, MetaData, String, Text, Integer,
create_engine)
from sqlalchemy.sql import and_
from sqlalchemy import exceptions as sa_exceptions
from sqlalchemy.sql import bindparam
from migrate import exceptions
from migrate.changeset import SQLA_07
from migrate.versioning import genmodel, schemadiff
from migrate.versioning.repository import Repository
from migrate.versioning.util import load_model
from migrate.versioning.version import VerNum
log = logging.getLogger(__name__)
class ControlledSchema(object):
"""A database under version control"""
def __init__(self, engine, repository):
if isinstance(repository, basestring):
repository = Repository(repository)
self.engine = engine
self.repository = repository
self.meta = MetaData(engine)
self.load()
def __eq__(self, other):
"""Compare two schemas by repositories and versions"""
return (self.repository is other.repository \
and self.version == other.version)
def load(self):
"""Load controlled schema version info from DB"""
tname = self.repository.version_table
try:
if not hasattr(self, 'table') or self.table is None:
self.table = Table(tname, self.meta, autoload=True)
result = self.engine.execute(self.table.select(
self.table.c.repository_id == str(self.repository.id)))
data = list(result)[0]
except:
cls, exc, tb = sys.exc_info()
raise exceptions.DatabaseNotControlledError, exc.__str__(), tb
self.version = data['version']
return data
def drop(self):
"""
Remove version control from a database.
"""
if SQLA_07:
try:
self.table.drop()
except sa_exceptions.DatabaseError:
raise exceptions.DatabaseNotControlledError(str(self.table))
else:
try:
self.table.drop()
except (sa_exceptions.SQLError):
raise exceptions.DatabaseNotControlledError(str(self.table))
def changeset(self, version=None):
"""API to Changeset creation.
Uses self.version for start version and engine.name
to get database name.
"""
database = self.engine.name
start_ver = self.version
changeset = self.repository.changeset(database, start_ver, version)
return changeset
def runchange(self, ver, change, step):
startver = ver
endver = ver + step
# Current database version must be correct! Don't run if corrupt!
if self.version != startver:
raise exceptions.InvalidVersionError("%s is not %s" % \
(self.version, startver))
# Run the change
change.run(self.engine, step)
# Update/refresh database version
self.update_repository_table(startver, endver)
self.load()
def update_repository_table(self, startver, endver):
"""Update version_table with new information"""
update = self.table.update(and_(self.table.c.version == int(startver),
self.table.c.repository_id == str(self.repository.id)))
self.engine.execute(update, version=int(endver))
def upgrade(self, version=None):
"""
Upgrade (or downgrade) to a specified version, or latest version.
"""
changeset = self.changeset(version)
for ver, change in changeset:
self.runchange(ver, change, changeset.step)
def update_db_from_model(self, model):
"""
Modify the database to match the structure of the current Python model.
"""
model = load_model(model)
diff = schemadiff.getDiffOfModelAgainstDatabase(
model, self.engine, excludeTables=[self.repository.version_table]
)
genmodel.ModelGenerator(diff,self.engine).runB2A()
self.update_repository_table(self.version, int(self.repository.latest))
self.load()
@classmethod
def create(cls, engine, repository, version=None):
"""
Declare a database to be under a repository's version control.
:raises: :exc:`DatabaseAlreadyControlledError`
:returns: :class:`ControlledSchema`
"""
# Confirm that the version # is valid: positive, integer,
# exists in repos
if isinstance(repository, basestring):
repository = Repository(repository)
version = cls._validate_version(repository, version)
table = cls._create_table_version(engine, repository, version)
# TODO: history table
# Load repository information and return
return cls(engine, repository)
@classmethod
def _validate_version(cls, repository, version):
"""
Ensures this is a valid version number for this repository.
:raises: :exc:`InvalidVersionError` if invalid
:return: valid version number
"""
if version is None:
version = 0
try:
version = VerNum(version) # raises valueerror
if version < 0 or version > repository.latest:
raise ValueError()
except ValueError:
raise exceptions.InvalidVersionError(version)
return version
@classmethod
def _create_table_version(cls, engine, repository, version):
"""
Creates the versioning table in a database.
:raises: :exc:`DatabaseAlreadyControlledError`
"""
# Create tables
tname = repository.version_table
meta = MetaData(engine)
table = Table(
tname, meta,
Column('repository_id', String(250), primary_key=True),
Column('repository_path', Text),
Column('version', Integer), )
# there can be multiple repositories/schemas in the same db
if not table.exists():
table.create()
# test for existing repository_id
s = table.select(table.c.repository_id == bindparam("repository_id"))
result = engine.execute(s, repository_id=repository.id)
if result.fetchone():
raise exceptions.DatabaseAlreadyControlledError
# Insert data
engine.execute(table.insert().values(
repository_id=repository.id,
repository_path=repository.path,
version=int(version)))
return table
@classmethod
def compare_model_to_db(cls, engine, model, repository):
"""
Compare the current model against the current database.
"""
if isinstance(repository, basestring):
repository = Repository(repository)
model = load_model(model)
diff = schemadiff.getDiffOfModelAgainstDatabase(
model, engine, excludeTables=[repository.version_table])
return diff
@classmethod
def create_model(cls, engine, repository, declarative=False):
"""
Dump the current database as a Python model.
"""
if isinstance(repository, basestring):
repository = Repository(repository)
diff = schemadiff.getDiffOfModelAgainstDatabase(
MetaData(), engine, excludeTables=[repository.version_table]
)
return genmodel.ModelGenerator(diff, engine, declarative).genBDefinition()
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