1 files changed, 62 insertions, 0 deletions
diff --git a/oslo_db/sqlalchemy/types.py b/oslo_db/sqlalchemy/types.py
new file mode 100644
index 0000000..477ed3f
--- /dev/null
+++ b/oslo_db/sqlalchemy/types.py
@@ -0,0 +1,62 @@
+#    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.
+
+import json
+
+from sqlalchemy.types import TypeDecorator, Text
+
+
+class JsonEncodedType(TypeDecorator):
+    """Base column type for data serialized as JSON-encoded string in db."""
+    type = None
+    impl = Text
+
+    def process_bind_param(self, value, dialect):
+        if value is None:
+            if self.type is not None:
+                # Save default value according to current type to keep the
+                # interface consistent.
+                value = self.type()
+        elif self.type is not None and not isinstance(value, self.type):
+            raise TypeError("%s supposes to store %s objects, but %s given"
+                            % (self.__class__.__name__,
+                               self.type.__name__,
+                               type(value).__name__))
+        serialized_value = json.dumps(value)
+        return serialized_value
+
+    def process_result_value(self, value, dialect):
+        if value is not None:
+            value = json.loads(value)
+        return value
+
+
+class JsonEncodedDict(JsonEncodedType):
+    """Represents dict serialized as json-encoded string in db.
+
+    Note that this type does NOT track mutations. If you want to update it, you
+    have to assign existing value to a temporary variable, update, then assign
+    back. See this page for more robust work around:
+    http://docs.sqlalchemy.org/en/rel_1_0/orm/extensions/mutable.html
+    """
+    type = dict
+
+
+class JsonEncodedList(JsonEncodedType):
+    """Represents list serialized as json-encoded string in db.
+
+    Note that this type does NOT track mutations. If you want to update it, you
+    have to assign existing value to a temporary variable, update, then assign
+    back. See this page for more robust work around:
+    http://docs.sqlalchemy.org/en/rel_1_0/orm/extensions/mutable.html
+    """
+    type = list