fix: same type list (#1492)

* fix: same type list

* chore: improve test

Author: superlevure

Diff for: graphene_django/fields.py

@@ -20,17 +20,20 @@
 
 class DjangoListField(Field):
     def __init__(self, _type, *args, **kwargs):
-        from .types import DjangoObjectType
-
         if isinstance(_type, NonNull):
             _type = _type.of_type
 
         # Django would never return a Set of None  vvvvvvv
         super().__init__(List(NonNull(_type)), *args, **kwargs)
 
+    @property
+    def type(self):
+        from .types import DjangoObjectType
+
         assert issubclass(
             self._underlying_type, DjangoObjectType
-        ), "DjangoListField only accepts DjangoObjectType types"
+        ), "DjangoListField only accepts DjangoObjectType types as underlying type"
+        return super().type
 
     @property
     def _underlying_type(self):

Diff for: graphene_django/tests/models.py

@@ -6,6 +6,9 @@
 
 class Person(models.Model):
     name = models.CharField(max_length=30)
+    parent = models.ForeignKey(
+        "self", on_delete=models.CASCADE, null=True, blank=True, related_name="children"
+    )
 
 
 class Pet(models.Model):

Diff for: graphene_django/tests/test_fields.py

@@ -12,17 +12,23 @@
     Article as ArticleModel,
     Film as FilmModel,
     FilmDetails as FilmDetailsModel,
+    Person as PersonModel,
     Reporter as ReporterModel,
 )
 
 
 class TestDjangoListField:
     def test_only_django_object_types(self):
-        class TestType(ObjectType):
-            foo = String()
+        class Query(ObjectType):
+            something = DjangoListField(String)
+
+        with pytest.raises(TypeError) as excinfo:
+            Schema(query=Query)
 
-        with pytest.raises(AssertionError):
-            DjangoListField(TestType)
+        assert (
+            "Query fields cannot be resolved. DjangoListField only accepts DjangoObjectType types as underlying type"
+            in str(excinfo.value)
+        )
 
     def test_only_import_paths(self):
         list_field = DjangoListField("graphene_django.tests.schema.Human")
@@ -262,6 +268,69 @@ class Query(ObjectType):
             ]
         }
 
+    def test_same_type_nested_list_field(self):
+        class Person(DjangoObjectType):
+            class Meta:
+                model = PersonModel
+                fields = ("name", "parent")
+
+            children = DjangoListField(lambda: Person)
+
+        class Query(ObjectType):
+            persons = DjangoListField(Person)
+
+        schema = Schema(query=Query)
+
+        query = """
+            query {
+                persons {
+                    name
+                    children {
+                        name
+                    }
+                }
+            }
+        """
+
+        p1 = PersonModel.objects.create(name="Tara")
+        PersonModel.objects.create(name="Debra")
+
+        PersonModel.objects.create(
+            name="Toto",
+            parent=p1,
+        )
+        PersonModel.objects.create(
+            name="Tata",
+            parent=p1,
+        )
+
+        result = schema.execute(query)
+
+        assert not result.errors
+        assert result.data == {
+            "persons": [
+                {
+                    "name": "Tara",
+                    "children": [
+                        {"name": "Toto"},
+                        {"name": "Tata"},
+                    ],
+                },
+                {
+                    "name": "Debra",
+                    "children": [],
+                },
+                {
+                    "name": "Toto",
+                    "children": [],
+                },
+                {
+                    "name": "Tata",
+                    "children": [],
+                },
+            ]
+        }
+
     def test_get_queryset_filter(self):
         class Reporter(DjangoObjectType):
             class Meta: