# 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 as mapperutil 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, l) except exc.UnmappedColumnError: _raise_col_to_prop(False, source_mapper, l, dest_mapper, r) try: dest_mapper._set_state_attr_by_column(dest, 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, 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, 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, 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) if len(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, 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) )