lazy: only create resultset on numeric access to __getitem__ (#33262)

tests/test_formdata.py

@@ -795,6 +795,13 @@ def test_lazy_formdata_queryset(pub, variable_test_data):
     qs = lazy_formdata.objects.pending().order_by('id')
     assert [x.number for x in qs] == ['1-1', '1-2', '1-3', '1-4', '1-5', '1-6', '1-7']
 
+    # Check accessing an non-numeric attribute doesn't try to cache things
+    # (see code for explanation)
+    manager = lazy_formdata.objects
+    with pytest.raises(TypeError):
+        manager['drafts']
+    assert manager._cached_resultset is None
+
 def test_lazy_formdata_queryset_distance(pub, variable_test_data):
     lazy_formdata = variable_test_data
     formdef = lazy_formdata._formdef

wcs/variables.py

@@ -110,6 +110,15 @@ class LazyFormDefObjectsManager(object):
         return self.count
 
     def __getitem__(self, key):
+        try:
+            int(key)
+        except ValueError:
+            # A django template doing formdef.objects.drafts would start by
+            # doing ['drafts'], that would raise TypeError and then continue
+            # to accessing .drafts (this is done in _resolve_lookup).
+            # We need to abort earlier as we don't want to load all formdata
+            # in that situation.
+            raise TypeError
         if self._cached_resultset is None:
             self._cached_resultset = [LazyFormData(x) for x in
                     self._formdef.data_class().select(clause=self._criterias, order_by=self._order_by)]