types: Set 'cache_ok' (redux)

In change Idf6fd858fad9521c7c5ba82c31b6d3077756abd9, we defined the
'cache_ok' key on a number of custom types. However, we relied on this
attribute being inheritable which is not the case due to how that
attribute is checked for [1]. As a result, we must set this attribute on
every one of our custom types.

[1] https://github.com/sqlalchemy/sqlalchemy/blob/rel_1_4_41/lib/sqlalchemy/sql/type_api.py#L984

Change-Id: I005af8c7afe3b5104068ca153aecbfe54e163ca3
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/oslo_db/sqlalchemy/types.py b/oslo_db/sqlalchemy/types.py
index a86f5ac..fe40bbd 100644
--- a/oslo_db/sqlalchemy/types.py
+++ b/oslo_db/sqlalchemy/types.py
@@ -69,6 +69,8 @@ class JsonEncodedDict(JsonEncodedType):
     """
 
     type = dict
+    cache_ok = True
+    """This type is safe to cache."""
 
 
 class JsonEncodedList(JsonEncodedType):
@@ -81,6 +83,8 @@ class JsonEncodedList(JsonEncodedType):
     """
 
     type = list
+    cache_ok = True
+    """This type is safe to cache."""
 
 
 class SoftDeleteInteger(TypeDecorator):
@@ -120,9 +124,11 @@ class String(_String):
 
     mysql_ndb_type is used to override the String with another data type.
     mysql_ndb_size is used to adjust the length of the String.
-
     """
 
+    cache_ok = True
+    """This type is safe to cache."""
+
     def __init__(
             self, length, mysql_ndb_length=None, mysql_ndb_type=None, **kw):
         """Initialize options."""