1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
|
# Copyright 2014 Tesora Inc.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
from migrate.changeset.constraint import ForeignKeyConstraint
from sqlalchemy.engine import reflection
def get_foreign_key_constraint_names(engine, table, columns,
ref_table, ref_columns):
"""Retrieve the names of foreign key constraints that match
the given criteria.
:param engine: The sqlalchemy engine to be used.
:param table: Name of the child table.
:param columns: List of the foreign key columns.
:param ref_table: Name of the parent table.
:param ref_columns: List of the referenced columns.
:return: List of foreign key constraint names.
"""
constraint_names = []
inspector = reflection.Inspector.from_engine(engine)
fks = inspector.get_foreign_keys(table)
for fk in fks:
if (fk['referred_table'] == ref_table
and fk['constrained_columns'] == columns
and fk['referred_columns'] == ref_columns):
constraint_names.append(fk['name'])
return constraint_names
def drop_foreign_key_constraints(constraint_names, columns,
ref_columns):
"""Drop the foreign key constraints that match the given
criteria.
:param constraint_names: List of foreign key constraint names
:param columns: List of the foreign key columns.
:param ref_columns: List of the referenced columns.
"""
for constraint_name in constraint_names:
fkey_constraint = ForeignKeyConstraint(columns=columns,
refcolumns=ref_columns,
name=constraint_name)
fkey_constraint.drop()
def create_foreign_key_constraints(constraint_names, columns,
ref_columns):
"""Create the foreign key constraints that match the given
criteria.
:param constraint_names: List of foreign key constraint names
:param columns: List of the foreign key columns.
:param ref_columns: List of the referenced columns.
"""
for constraint_name in constraint_names:
fkey_constraint = ForeignKeyConstraint(columns=columns,
refcolumns=ref_columns,
name=constraint_name)
fkey_constraint.create()
|
