# mapper/sync.py
# Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Michael Bayer mike_mp@zzzcomputing.com
#
# 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
def populate(source, source_mapper, dest, dest_mapper,
synchronize_pairs, uowcommit, passive_updates):
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, dest_mapper, r)
try:
dest_mapper._set_state_attr_by_column(dest, dest.dict, r, value)
except exc.UnmappedColumnError:
_raise_col_to_prop(True, source_mapper, l, dest_mapper, r)
# techically 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 l.primary_key and r.primary_key and \
r.references(l) and passive_updates:
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._get_col_to_prop(l)
except exc.UnmappedColumnError:
_raise_col_to_prop(False, source_mapper, l, None, r)
history = uowcommit.get_attribute_history(source, prop.key, passive=True)
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, source_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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