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# orm/sync.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
"""private module containing functions used for copying data
between instances based on join conditions.
"""
from sqlalchemy.orm import exc, util as mapperutil, attributes
def populate(source, source_mapper, dest, dest_mapper,
synchronize_pairs, uowcommit, flag_cascaded_pks):
source_dict = source.dict
dest_dict = dest.dict
for l, r in synchronize_pairs:
try:
# inline of source_mapper._get_state_attr_by_column
prop = source_mapper._columntoproperty[l]
value = source.manager[prop.key].impl.get(source, source_dict,
attributes.PASSIVE_OFF)
except exc.UnmappedColumnError:
_raise_col_to_prop(False, source_mapper, l, dest_mapper, r)
try:
# inline of dest_mapper._set_state_attr_by_column
prop = dest_mapper._columntoproperty[r]
dest.manager[prop.key].impl.set(dest, dest_dict, value, None)
except exc.UnmappedColumnError:
_raise_col_to_prop(True, source_mapper, l, dest_mapper, r)
# technically the "r.primary_key" check isn't
# needed here, but we check for this condition to limit
# how often this logic is invoked for memory/performance
# reasons, since we only need this info for a primary key
# destination.
if flag_cascaded_pks and l.primary_key and \
r.primary_key and \
r.references(l):
uowcommit.attributes[("pk_cascaded", dest, r)] = True
def clear(dest, dest_mapper, synchronize_pairs):
for l, r in synchronize_pairs:
if r.primary_key:
raise AssertionError(
"Dependency rule tried to blank-out primary key "
"column '%s' on instance '%s'" %
(r, mapperutil.state_str(dest))
)
try:
dest_mapper._set_state_attr_by_column(dest, dest.dict, r, None)
except exc.UnmappedColumnError:
_raise_col_to_prop(True, None, l, dest_mapper, r)
def update(source, source_mapper, dest, old_prefix, synchronize_pairs):
for l, r in synchronize_pairs:
try:
oldvalue = source_mapper._get_committed_attr_by_column(source.obj(), l)
value = source_mapper._get_state_attr_by_column(source, source.dict, l)
except exc.UnmappedColumnError:
_raise_col_to_prop(False, source_mapper, l, None, r)
dest[r.key] = value
dest[old_prefix + r.key] = oldvalue
def populate_dict(source, source_mapper, dict_, synchronize_pairs):
for l, r in synchronize_pairs:
try:
value = source_mapper._get_state_attr_by_column(source, source.dict, l)
except exc.UnmappedColumnError:
_raise_col_to_prop(False, source_mapper, l, None, r)
dict_[r.key] = value
def source_modified(uowcommit, source, source_mapper, synchronize_pairs):
"""return true if the source object has changes from an old to a
new value on the given synchronize pairs
"""
for l, r in synchronize_pairs:
try:
prop = source_mapper._columntoproperty[l]
except exc.UnmappedColumnError:
_raise_col_to_prop(False, source_mapper, l, None, r)
history = uowcommit.get_attribute_history(source, prop.key,
attributes.PASSIVE_NO_INITIALIZE)
return bool(history.deleted)
else:
return False
def _raise_col_to_prop(isdest, source_mapper, source_column, dest_mapper, dest_column):
if isdest:
raise exc.UnmappedColumnError(
"Can't execute sync rule for destination column '%s'; "
"mapper '%s' does not map this column. Try using an explicit"
" `foreign_keys` collection which does not include this column "
"(or use a viewonly=True relation)." % (dest_column, dest_mapper)
)
else:
raise exc.UnmappedColumnError(
"Can't execute sync rule for source column '%s'; mapper '%s' "
"does not map this column. Try using an explicit `foreign_keys`"
" collection which does not include destination column '%s' (or "
"use a viewonly=True relation)." %
(source_column, source_mapper, dest_column)
)
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