Check prepare had been called when project is called

django_readers/specs.py

@@ -1,5 +1,5 @@
 from django_readers import pairs
-from django_readers.utils import queries_disabled
+from django_readers.utils import with_prepared_checker, with_queries_disabled
 
 
 def process_item(item):
@@ -16,7 +16,9 @@ def process_item(item):
 
 
 def process(spec):
-    return queries_disabled(pairs.combine(*(process_item(item) for item in spec)))
+    return with_prepared_checker(
+        with_queries_disabled(pairs.combine(*(process_item(item) for item in spec)))
+    )
 
 
 def relationship(name, relationship_spec, to_attr=None):

django_readers/utils.py

@@ -44,12 +44,30 @@ def none_safe_get_attr(obj):
     return none_safe_get_attr
 
 
-def queries_disabled(pair):
+def with_queries_disabled(pair):
     prepare, project = pair
     decorator = zen_queries.queries_disabled() if zen_queries else lambda fn: fn
     return decorator(prepare), decorator(project)
 
 
+def with_prepared_checker(pair):
+    prepare, project = pair
+
+    is_prepared = False
+
+    def wrapped_prepare(qs):
+        nonlocal is_prepared
+        is_prepared = True
+        return prepare(qs)
+
+    def wrapped_project(qs):
+        if not is_prepared:
+            raise Exception("QuerySet must be prepared before projection")
+        return project(qs)
+
+    return (wrapped_prepare, wrapped_project)
+
+
 class SpecVisitor:
     def visit(self, spec):
         return [self.visit_item(item) for item in spec]

tests/test_rest_framework.py

@@ -110,6 +110,29 @@ def test_detail(self):
             },
         )
 
+    def test_override_getqueryset_must_call_prepare(self):
+        Widget.objects.create()
+
+        class WidgetListView(SpecMixin, ListAPIView):
+            spec = [
+                "name",
+            ]
+
+            def get_queryset(self):
+                queryset = Widget.objects.all()
+                # Should call self.prepare(queryset) here
+                return queryset
+
+        request = APIRequestFactory().get("/")
+        view = WidgetListView.as_view()
+
+        with self.assertRaises(Exception) as cm:
+            view(request)
+
+        self.assertEqual(
+            str(cm.exception), "QuerySet must be prepared before projection"
+        )
+
 
 class SpecToSerializerClassTestCase(TestCase):
     def test_basic_spec(self):