openstack
/
neutron
Code Issues Proposed changes

Add function to remove constraints from database 

Function used in alembic database migration script to
remove foreign keys from table doesn't remove unique constraint
created for such fk in table.
Sometimes there is need to remove also such unique constraint during
database upgrade.
Removing unique constraint is little bit different in mysql and
postgresql databases because names of such constraints are different.
This patch introduces function to remove constraints from table
during migration.
It is also used in remove_fks_from_table() function to allow removal
unique constraints when fk is removed.

Change-Id: I7e7732560984b1c1e45230434ddc4be8cf5ab630
Closes-Bug: #1599840
This commit is contained in:
Sławek Kapłoński 2016-07-07 13:05:36 +00:00 committed by Sławek Kapłoński
parent fb88d07bd1
commit 7a206a942f
1 changed files with 24 additions and 1 deletions
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25
neutron/db/migration/__init__.py
View File

@ -157,6 +157,27 @@ def create_table_if_not_exist_psql(table_name, values):
'columns': values})
def get_unique_constraints_map(table):
inspector = reflection.Inspector.from_engine(op.get_bind())
return {
tuple(sorted(cons['column_names'])): cons['name']
for cons in inspector.get_unique_constraints(table)
}
def remove_fk_unique_constraints(table, foreign_keys):
unique_constraints_map = get_unique_constraints_map(table)
for fk in foreign_keys:
constraint_name = unique_constraints_map.get(
tuple(sorted(fk['constrained_columns'])))
if constraint_name:
op.drop_constraint(
constraint_name=constraint_name,
table_name=table,
type_="unique"
)
def remove_foreign_keys(table, foreign_keys):
for fk in foreign_keys:
op.drop_constraint(
@ -179,11 +200,13 @@ def create_foreign_keys(table, foreign_keys):
@contextlib.contextmanager
def remove_fks_from_table(table):
def remove_fks_from_table(table, remove_unique_constraints=False):
try:
inspector = reflection.Inspector.from_engine(op.get_bind())
foreign_keys = inspector.get_foreign_keys(table)
remove_foreign_keys(table, foreign_keys)
if remove_unique_constraints:
remove_fk_unique_constraints(table, foreign_keys)
yield
finally:
create_foreign_keys(table, foreign_keys)