Fix issue with scheduled queries

redash/models/__init__.py

@@ -387,6 +387,10 @@ def groups(self):
 
 
 def should_schedule_next(previous_iteration, now, interval, time=None, day_of_week=None, failures=0):
+    # if previous_iteration is None, it means the query has never been run before
+    # so we should schedule it immediately
+    if previous_iteration is None:
+        return True
     # if time exists then interval > 23 hours (82800s)
     # if day_of_week exists then interval > 6 days (518400s)
     if time is None:
@@ -602,6 +606,11 @@ def outdated_queries(cls):
                 if query.schedule.get("disabled"):
                     continue
 
+                # Skip queries that have None for all schedule values. It's unclear whether this
+                # something that can happen in practice, but we have a test case for it.
+                if all(value is None for value in query.schedule.values()):
+                    continue
+
                 if query.schedule["until"]:
                     schedule_until = pytz.utc.localize(datetime.datetime.strptime(query.schedule["until"], "%Y-%m-%d"))
 
@@ -613,7 +622,7 @@ def outdated_queries(cls):
                 )
 
                 if should_schedule_next(
-                    retrieved_at or now,
+                    retrieved_at,
                     now,
                     query.schedule["interval"],
                     query.schedule["time"],

tests/test_models.py

@@ -216,6 +216,20 @@ def test_enqueues_query_only_once(self):
 
         self.assertEqual(list(models.Query.outdated_queries()), [query2])
 
+    def test_enqueues_scheduled_query_without_latest_query_data(self):
+        """
+        Queries with a schedule but no latest_query_data will still be reported by Query.outdated_queries()
+        """
+        query = self.factory.create_query(
+            schedule=self.schedule(interval="60"),
+            data_source=self.factory.create_data_source(),
+        )
+
+        outdated_queries = models.Query.outdated_queries()
+        self.assertEqual(query.latest_query_data, None)
+        self.assertEqual(len(outdated_queries), 1)
+        self.assertIn(query, outdated_queries)
+
     def test_enqueues_query_with_correct_data_source(self):
         """
         Queries from different data sources will be reported by