Fix ManyToMany schema mapping

graphene_django/tests/test_utils.py

@@ -0,0 +1,12 @@
+from ..utils import get_model_fields
+from .models import Film, Reporter
+
+
+def test_get_model_fields_no_duplication():
+    reporter_fields = get_model_fields(Reporter)
+    reporter_name_set = set([field[0] for field in reporter_fields])
+    assert len(reporter_fields) == len(reporter_name_set)
+
+    film_fields = get_model_fields(Film)
+    film_name_set = set([field[0] for field in film_fields])
+    assert len(film_fields) == len(film_name_set)

graphene_django/utils.py

@@ -21,8 +21,12 @@ class LazyList(object):
     DJANGO_FILTER_INSTALLED = False
 
 
-def get_reverse_fields(model):
+def get_reverse_fields(model, local_field_names):
     for name, attr in model.__dict__.items():
+        # Don't duplicate any local fields
+        if name in local_field_names:
+            continue
+
         # Django =>1.9 uses 'rel', django <1.9 uses 'related'
         related = getattr(attr, 'rel', None) or \
             getattr(attr, 'related', None)
@@ -44,15 +48,18 @@ def maybe_queryset(value):
 
 
 def get_model_fields(model):
-    reverse_fields = get_reverse_fields(model)
-    all_fields = [
+    local_fields = [
         (field.name, field)
         for field
         in sorted(list(model._meta.fields) +
                   list(model._meta.local_many_to_many))
     ]
 
-    all_fields += list(reverse_fields)
+    # Make sure we don't duplicate local fields with "reverse" version
+    local_field_names = [field[0] for field in local_fields]
+    reverse_fields = get_reverse_fields(model, local_field_names)
+
+    all_fields = local_fields + list(reverse_fields)
 
     return all_fields