99 lines
4.3 KiB
Python
99 lines
4.3 KiB
Python
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# mapper/sync.py
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# Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Michael Bayer mike_mp@zzzcomputing.com
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: http://www.opensource.org/licenses/mit-license.php
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"""private module containing functions used for copying data
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between instances based on join conditions.
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"""
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from sqlalchemy.orm import exc, util as mapperutil
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def populate(source, source_mapper, dest, dest_mapper,
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synchronize_pairs, uowcommit, passive_updates):
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for l, r in synchronize_pairs:
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try:
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value = source_mapper._get_state_attr_by_column(source, l)
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except exc.UnmappedColumnError:
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_raise_col_to_prop(False, source_mapper, l, dest_mapper, r)
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try:
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dest_mapper._set_state_attr_by_column(dest, r, value)
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except exc.UnmappedColumnError:
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_raise_col_to_prop(True, source_mapper, l, dest_mapper, r)
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# techically the "r.primary_key" check isn't
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# needed here, but we check for this condition to limit
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# how often this logic is invoked for memory/performance
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# reasons, since we only need this info for a primary key
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# destination.
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if l.primary_key and r.primary_key and \
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r.references(l) and passive_updates:
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uowcommit.attributes[("pk_cascaded", dest, r)] = True
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def clear(dest, dest_mapper, synchronize_pairs):
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for l, r in synchronize_pairs:
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if r.primary_key:
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raise AssertionError(
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"Dependency rule tried to blank-out primary key "
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"column '%s' on instance '%s'" %
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(r, mapperutil.state_str(dest))
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)
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try:
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dest_mapper._set_state_attr_by_column(dest, r, None)
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except exc.UnmappedColumnError:
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_raise_col_to_prop(True, None, l, dest_mapper, r)
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def update(source, source_mapper, dest, old_prefix, synchronize_pairs):
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for l, r in synchronize_pairs:
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try:
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oldvalue = source_mapper._get_committed_attr_by_column(source.obj(), l)
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value = source_mapper._get_state_attr_by_column(source, l)
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except exc.UnmappedColumnError:
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_raise_col_to_prop(False, source_mapper, l, None, r)
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dest[r.key] = value
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dest[old_prefix + r.key] = oldvalue
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def populate_dict(source, source_mapper, dict_, synchronize_pairs):
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for l, r in synchronize_pairs:
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try:
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value = source_mapper._get_state_attr_by_column(source, l)
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except exc.UnmappedColumnError:
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_raise_col_to_prop(False, source_mapper, l, None, r)
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dict_[r.key] = value
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def source_modified(uowcommit, source, source_mapper, synchronize_pairs):
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"""return true if the source object has changes from an old to a
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new value on the given synchronize pairs
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"""
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for l, r in synchronize_pairs:
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try:
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prop = source_mapper._get_col_to_prop(l)
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except exc.UnmappedColumnError:
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_raise_col_to_prop(False, source_mapper, l, None, r)
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history = uowcommit.get_attribute_history(source, prop.key, passive=True)
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if len(history.deleted):
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return True
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else:
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return False
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def _raise_col_to_prop(isdest, source_mapper, source_column, dest_mapper, dest_column):
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if isdest:
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raise exc.UnmappedColumnError(
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"Can't execute sync rule for destination column '%s'; "
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"mapper '%s' does not map this column. Try using an explicit"
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" `foreign_keys` collection which does not include this column "
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"(or use a viewonly=True relation)." % (dest_column, source_mapper)
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)
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else:
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raise exc.UnmappedColumnError(
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"Can't execute sync rule for source column '%s'; mapper '%s' "
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"does not map this column. Try using an explicit `foreign_keys`"
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" collection which does not include destination column '%s' (or "
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"use a viewonly=True relation)." %
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(source_column, source_mapper, dest_column)
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)
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