119 lines
4.6 KiB
Python
119 lines
4.6 KiB
Python
# orm/sync.py
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# Copyright (C) 2005-2014 the SQLAlchemy authors and contributors <see AUTHORS file>
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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 . import exc, util as orm_util, attributes
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def populate(source, source_mapper, dest, dest_mapper,
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synchronize_pairs, uowcommit, flag_cascaded_pks):
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source_dict = source.dict
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dest_dict = dest.dict
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for l, r in synchronize_pairs:
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try:
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# inline of source_mapper._get_state_attr_by_column
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prop = source_mapper._columntoproperty[l]
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value = source.manager[prop.key].impl.get(source, source_dict,
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attributes.PASSIVE_OFF)
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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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# inline of dest_mapper._set_state_attr_by_column
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prop = dest_mapper._columntoproperty[r]
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dest.manager[prop.key].impl.set(dest, dest_dict, value, None)
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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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# technically 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 flag_cascaded_pks and l.primary_key and \
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r.primary_key and \
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r.references(l):
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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, orm_util.state_str(dest))
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)
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try:
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dest_mapper._set_state_attr_by_column(dest, dest.dict, 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(
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source.obj(), l)
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value = source_mapper._get_state_attr_by_column(
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source, source.dict, 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(
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source, source.dict, 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._columntoproperty[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,
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attributes.PASSIVE_NO_INITIALIZE)
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if bool(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,
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dest_mapper, dest_column):
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if isdest:
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raise exc.UnmappedColumnError("Can't execute sync rule for "
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"destination column '%s'; mapper '%s' does not map "
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"this column. Try using an explicit `foreign_keys` "
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"collection which does not include this column (or use "
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"a viewonly=True relation)." % (dest_column,
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dest_mapper))
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else:
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raise exc.UnmappedColumnError("Can't execute sync rule for "
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"source column '%s'; mapper '%s' does not map this "
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"column. Try using an explicit `foreign_keys` "
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"collection which does not include destination column "
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"'%s' (or use a viewonly=True relation)."
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% (source_column, source_mapper, dest_column))
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