simplify some type checks by fixing graphql schema

dnscms/events/models.py

@@ -49,9 +49,9 @@ class EventCategory(models.Model):
     panels = [FieldPanel("name"), FieldPanel("slug"), FieldPanel("show_in_filters")]
 
     graphql_fields = [
-        GraphQLString("name"),
-        GraphQLString("slug"),
-        GraphQLBoolean("show_in_filters"),
+        GraphQLString("name", required=True),
+        GraphQLString("slug", required=True),
+        GraphQLBoolean("show_in_filters", required=True),
     ]
 
     class Meta:
@@ -171,8 +171,20 @@ class EventPage(Page):
         GraphQLInt("price_regular"),
         GraphQLInt("price_student"),
         GraphQLInt("price_member"),
-        GraphQLCollection(GraphQLForeignKey, "categories", "events.EventCategory"),
-        GraphQLCollection(GraphQLForeignKey, "occurrences", "events.EventOccurrence"),
+        GraphQLCollection(
+            GraphQLForeignKey,
+            "categories",
+            "events.EventCategory",
+            required=True,
+            item_required=True,
+        ),
+        GraphQLCollection(
+            GraphQLForeignKey,
+            "occurrences",
+            "events.EventOccurrence",
+            required=True,
+            item_required=True,
+        ),
     ]
 
 
@@ -195,7 +207,7 @@ class EventOccurrence(Orderable):
     ]
 
     graphql_fields = [
-        GraphQLString("start"),
+        GraphQLString("start", required=True),
         GraphQLString("end"),
         GraphQLForeignKey("venue", "venues.VenuePage"),
     ]