Validate Meta.fields and Meta.exclude on DjangoObjectType

Resolves #840

graphene_django/tests/models.py

@@ -64,6 +64,9 @@ def __init__(self, *args, **kwargs):
         if self.reporter_type == 2:  # quick and dirty way without enums
             self.__class__ = CNNReporter
 
+    def some_method(self):
+        return 123
+
 
 class CNNReporterManager(models.Manager):
     def get_queryset(self):

graphene_django/tests/test_types.py

@@ -318,6 +318,30 @@ class Meta:
                 fields = "foo"
 
 
+@with_local_registry
+def test_django_objecttype_fields_exclude_exist_on_model():
+    with pytest.raises(Exception, match=r"Field .* doesn't exist"):
+
+        class Reporter(DjangoObjectType):
+            class Meta:
+                model = ReporterModel
+                fields = ["first_name", "foo", "email"]
+
+    with pytest.raises(Exception, match=r"Field .* doesn't exist"):
+
+        class Reporter2(DjangoObjectType):
+            class Meta:
+                model = ReporterModel
+                exclude = ["first_name", "foo", "email"]
+
+    with pytest.raises(Exception, match=r".* exists on model .* but it's not a field"):
+
+        class Reporter3(DjangoObjectType):
+            class Meta:
+                model = ReporterModel
+                fields = ["first_name", "some_method", "email"]
+
+
 class TestDjangoObjectType:
     @pytest.fixture
     def PetModel(self):

graphene_django/types.py

@@ -33,6 +33,24 @@ def construct_fields(
 ):
     _model_fields = get_model_fields(model)
 
+    # Validate the given fields against the model's fields.
+    model_field_names = set(field[0] for field in _model_fields)
+    for fields_list in (only_fields, exclude_fields):
+        if not fields_list:
+            continue
+        for name in fields_list:
+            if name in model_field_names:
+                continue
+
+            if hasattr(model, name):
+                raise Exception(
+                    '"{}" exists on model {} but it\'s not a field.'.format(name, model)
+                )
+            else:
+                raise Exception(
+                    'Field "{}" doesn\'t exist on model {}.'.format(name, model)
+                )
+
     fields = OrderedDict()
     for name, field in _model_fields:
         is_not_in_only = only_fields and name not in only_fields