59 lines
2.3 KiB
Python
59 lines
2.3 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright 2013 OpenStack LLC
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# Copyright 2013 Red Hat, Inc.
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import migrate
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import sqlalchemy
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# Different RDBMSs use different schemes for naming the Foreign Key
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# Constraints. SQLAlchemy does not yet attempt to determine the name
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# for the constraint, and instead attempts to deduce it from the column.
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# This fails on MySQL.
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def get_fkey_constraint_name(table, column_name):
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fkeys = [fk for fk in table.constraints
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if (column_name in fk.columns and
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isinstance(fk, sqlalchemy.ForeignKeyConstraint))]
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constraint_name = fkeys[0].name
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return constraint_name
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# remove_constraints and add_constraints both accept a list of dictionaries
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# that contain:
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# {'table': a sqlalchemy table. The constraint is added to to dropped from
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# this table.
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# 'fk_column': the name of a column on the above table, The constraint
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# is added to or dropped from this column
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# 'ref_column':a sqlalchemy column object. This is the reference column
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# for the constraint.
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def remove_constraints(constraints):
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for constraint_def in constraints:
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migrate.ForeignKeyConstraint(
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columns=[getattr(constraint_def['table'].c,
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constraint_def['fk_column'])],
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refcolumns=[constraint_def['ref_column']],
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name=(get_fkey_constraint_name
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(constraint_def['table'],
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constraint_def['fk_column']))).drop()
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def add_constraints(constraints):
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for constraint_def in constraints:
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migrate.ForeignKeyConstraint(
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columns=[getattr(constraint_def['table'].c,
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constraint_def['fk_column'])],
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refcolumns=[constraint_def['ref_column']]).create()
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