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# orm/sync.py
# Copyright (C) 2005-2019 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 . import attributes
from . import exc
from . import util as orm_util
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 bulk_populate_inherit_keys(source_dict, source_mapper, synchronize_pairs):
# a simplified version of populate() used by bulk insert mode
for l, r in synchronize_pairs:
try:
prop = source_mapper._columntoproperty[l]
value = source_dict[prop.key]
except exc.UnmappedColumnError:
_raise_col_to_prop(False, source_mapper, l, source_mapper, r)
try:
prop = source_mapper._columntoproperty[r]
source_dict[prop.key] = value
except exc.UnmappedColumnError:
_raise_col_to_prop(True, source_mapper, l, source_mapper, r)
def clear(dest, dest_mapper, synchronize_pairs):
for l, r in synchronize_pairs:
if (
r.primary_key
and dest_mapper._get_state_attr_by_column(dest, dest.dict, r)
not in orm_util._none_set
):
raise AssertionError(
"Dependency rule tried to blank-out primary key "
"column '%s' on instance '%s'" % (r, orm_util.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, passive=attributes.PASSIVE_OFF
)
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, passive=attributes.PASSIVE_OFF
)
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
)
if bool(history.deleted):
return True
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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