[bugfix] markup and iframe viz raise 'Empty query' (apache#4225)

closes apache#4222

Related to: apache#4016

superset/views/core.py

@@ -1035,8 +1035,7 @@ def generate_json(self, datasource_type, datasource_id, form_data,
             return self.get_query_string_response(viz_obj)
 
         try:
-            payload = viz_obj.get_payload(
-                force=force)
+            payload = viz_obj.get_payload(force=force)
         except Exception as e:
             logging.exception(e)
             return json_error_response(utils.error_msg_from_exception(e))

superset/viz.py

@@ -243,12 +243,12 @@ def cache_key(self, query_obj):
     def get_payload(self, force=False):
         """Handles caching around the json payload retrieval"""
         query_obj = self.query_obj()
-        cache_key = self.cache_key(query_obj)
+        cache_key = self.cache_key(query_obj) if query_obj else None
         cached_dttm = None
         data = None
         stacktrace = None
         rowcount = None
-        if not force and cache:
+        if cache_key and cache and not force:
             cache_value = cache.get(cache_key)
             if cache_value:
                 stats_logger.incr('loaded_from_cache')
@@ -536,7 +536,10 @@ class MarkupViz(BaseViz):
     verbose_name = _('Markup')
     is_timeseries = False
 
-    def get_df(self):
+    def query_obj(self):
+        return None
+
+    def get_df(self, query_obj=None):
         return None
 
     def get_data(self, df):
@@ -1573,7 +1576,10 @@ class IFrameViz(BaseViz):
     credits = 'a <a href="https://github.com/airbnb/superset">Superset</a> original'
     is_timeseries = False
 
-    def get_df(self):
+    def query_obj(self):
+        return None
+
+    def get_df(self, query_obj=None):
         return None