Restore the check_foreign_keys() method.1.4.1

This method was prematurely removed from oslo.db without
a deprecation phase, when Alembic added support for
foreign key autodetection.   oslo.db continues to use
alembic for this purpose, however the
ModelsMigrationsSync.check_foreign_keys() method is restored
directly for those projects which were calling into it
explicitly.

Change-Id: Id892567bd60d6b4b88765bbfe3cd5c5e75910b25

1 files changed, 72 insertions, 0 deletions

diff --git a/oslo_db/sqlalchemy/test_migrations.py b/oslo_db/sqlalchemy/test_migrations.py
index 8990790..9b65421 100644
--- a/oslo_db/sqlalchemy/test_migrations.py
+++ b/oslo_db/sqlalchemy/test_migrations.py
@@ -15,6 +15,7 @@
 #    under the License.
 
 import abc
+import collections
 import logging
 import pprint
 
@@ -510,6 +511,77 @@ class ModelsMigrationsSync(object):
             for table in tbs:
                 conn.execute(schema.DropTable(table))
 
+    FKInfo = collections.namedtuple('fk_info', ['constrained_columns',
+                                                'referred_table',
+                                                'referred_columns'])
+
+    def check_foreign_keys(self, metadata, bind):
+        """Compare foreign keys between model and db table.
+
+        :returns: a list that contains information about:
+
+         * should be a new key added or removed existing,
+         * name of that key,
+         * source table,
+         * referred table,
+         * constrained columns,
+         * referred columns
+
+         Output::
+
+             [('drop_key',
+               'testtbl_fk_check_fkey',
+               'testtbl',
+               fk_info(constrained_columns=(u'fk_check',),
+                       referred_table=u'table',
+                       referred_columns=(u'fk_check',)))]
+
+        DEPRECATED: this function is deprecated and will be removed from
+        oslo.db in a few releases. Alembic autogenerate.compare_metadata()
+        now includes foreign key comparison directly.
+
+        """
+
+        diff = []
+        insp = sqlalchemy.engine.reflection.Inspector.from_engine(bind)
+        # Get all tables from db
+        db_tables = insp.get_table_names()
+        # Get all tables from models
+        model_tables = metadata.tables
+        for table in db_tables:
+            if table not in model_tables:
+                continue
+            # Get all necessary information about key of current table from db
+            fk_db = dict((self._get_fk_info_from_db(i), i['name'])
+                         for i in insp.get_foreign_keys(table))
+            fk_db_set = set(fk_db.keys())
+            # Get all necessary information about key of current table from
+            # models
+            fk_models = dict((self._get_fk_info_from_model(fk), fk)
+                             for fk in model_tables[table].foreign_keys)
+            fk_models_set = set(fk_models.keys())
+            for key in (fk_db_set - fk_models_set):
+                diff.append(('drop_key', fk_db[key], table, key))
+                LOG.info(("Detected removed foreign key %(fk)r on "
+                          "table %(table)r"), {'fk': fk_db[key],
+                                               'table': table})
+            for key in (fk_models_set - fk_db_set):
+                diff.append(('add_key', fk_models[key], table, key))
+                LOG.info((
+                    "Detected added foreign key for column %(fk)r on table "
+                    "%(table)r"), {'fk': fk_models[key].column.name,
+                                   'table': table})
+        return diff
+
+    def _get_fk_info_from_db(self, fk):
+        return self.FKInfo(tuple(fk['constrained_columns']),
+                           fk['referred_table'],
+                           tuple(fk['referred_columns']))
+
+    def _get_fk_info_from_model(self, fk):
+        return self.FKInfo((fk.parent.name,), fk.column.table.name,
+                           (fk.column.name,))
+
     def test_models_sync(self):
         # recent versions of sqlalchemy and alembic are needed for running of
         # this test, but we already have them in requirements