Correct name for json_serializer / json_deserializer, document and test

The dialects that support json are supposed to take arguments
``json_serializer`` and ``json_deserializer`` at the create_engine() level,
however the SQLite dialect calls them ``_json_serilizer`` and
``_json_deserilalizer``.  The names have been corrected, the old names are
accepted with a change warning, and these parameters are now documented as
:paramref:`.create_engine.json_serializer` and
:paramref:`.create_engine.json_deserializer`.

Fixes: #4798
Change-Id: I1dbfe439b421fe9bb7ff3594ef455af8156f8851

1 files changed, 16 insertions, 0 deletions

diff --git a/lib/sqlalchemy/engine/create.py b/lib/sqlalchemy/engine/create.py
index 035953e99..cc8304131 100644
--- a/lib/sqlalchemy/engine/create.py
+++ b/lib/sqlalchemy/engine/create.py
@@ -234,6 +234,22 @@ def create_engine(url, **kwargs):
 
             :ref:`session_transaction_isolation` - for the ORM
 
+    :param json_deserializer: for dialects that support the :class:`.JSON`
+        datatype, this is a Python callable that will convert a JSON string
+        to a Python object.  By default, the Python ``json.loads`` function is
+        used.
+
+        .. versionchanged:: 1.3.7  The SQLite dialect renamed this from
+           ``_json_deserializer``.
+
+    :param json_serializer: for dialects that support the :class:`.JSON`
+        datatype, this is a Python callable that will render a given object
+        as JSON.   By default, the Python ``json.dumps`` function is used.
+
+        .. versionchanged:: 1.3.7  The SQLite dialect renamed this from
+           ``_json_serializer``.
+
+
     :param label_length=None: optional integer value which limits
         the size of dynamically generated column labels to that many
         characters. If less than 6, labels are generated as