Support JSON data in JSON API type

JSON API type now tries to load a string all the time, even if the data
is already decoded as part of the request. It seems easy to support
loading the data directly. We also handle TypeError so that we handle
non-dict incorrect values.

Change-Id: Ib8c21d95df96743e65bdf2bc88af5207cf78fd8f
Closes-Bug: #1590789

mistral/api/controllers/v2/types.py

@@ -107,8 +107,12 @@ class JsonType(wtypes.UserType):
         return value
 
     def frombasetype(self, value):
-        # Value must be a string.
+        if isinstance(value, dict):
+            return value
+        try:
             return json.loads(value) if value is not None else None
+        except TypeError as e:
+            raise ValueError(e)
 
     def tobasetype(self, value):
         # Value must be a dict.

mistral/tests/unit/api/v2/test_action_executions.py

@@ -197,6 +197,33 @@ class TestActionExecutionsController(base.APITest):
             save_result=True
         )
 
+    @mock.patch.object(rpc.EngineClient, 'start_action')
+    def test_post_json(self, f):
+        f.return_value = ACTION_EX_DB.to_dict()
+
+        resp = self.app.post_json(
+            '/v2/action_executions',
+            {
+                'name': 'std.echo',
+                'input': {},
+                'params': '{"save_result": true}'
+            }
+        )
+
+        self.assertEqual(201, resp.status_int)
+
+        action_exec = ACTION_EX
+        del action_exec['task_name']
+
+        self.assertDictEqual(ACTION_EX, resp.json)
+
+        f.assert_called_once_with(
+            ACTION_EX['name'],
+            json.loads(ACTION_EX['input']),
+            description=None,
+            save_result=True
+        )
+
     @mock.patch.object(rpc.EngineClient, 'start_action')
     def test_post_without_input(self, f):
         f.return_value = ACTION_EX_DB.to_dict()
@@ -230,6 +257,15 @@ class TestActionExecutionsController(base.APITest):
 
         self.assertEqual(400, resp.status_int)
 
+    def test_post_bad_json_input(self):
+        resp = self.app.post_json(
+            '/v2/action_executions',
+            {'input': 2},
+            expect_errors=True
+        )
+
+        self.assertEqual(400, resp.status_int)
+
     @mock.patch.object(rpc.EngineClient, 'on_action_complete')
     def test_put(self, f):
         f.return_value = UPDATED_ACTION_EX_DB