Allow an element's parent field to be set to null

arkindex/documents/serializers/elements.py

@@ -285,7 +285,7 @@ class ElementCreateSerializer(ElementLightSerializer):
         required=False,
         help_text='Link this element to an image by UUID via a polygon.',
     )
-    parent = serializers.PrimaryKeyRelatedField(queryset=Element.objects.none(), required=False)
+    parent = serializers.PrimaryKeyRelatedField(queryset=Element.objects.none(), required=False, allow_null=True)
     polygon = PolygonField(
         required=False,
         help_text='Set the polygon linking this element to the image. '

arkindex/documents/tests/test_elements_api.py

@@ -297,6 +297,7 @@ class TestElementsAPI(FixtureAPITestCase):
                 'corpus': str(volume.corpus.id),
                 'name': volume.name,
                 'type': volume.type.slug,
+                'parent': None,
                 'source': None,
             }
         )
@@ -323,6 +324,7 @@ class TestElementsAPI(FixtureAPITestCase):
                 'corpus': str(page.corpus.id),
                 'name': page.name,
                 'type': page.type.slug,
+                'parent': None,
                 'source': None,
             }
         )
@@ -385,6 +387,7 @@ class TestElementsAPI(FixtureAPITestCase):
                 'corpus': str(page.corpus.id),
                 'name': page.name,
                 'type': page.type.slug,
+                'parent': None,
                 'source': None,
             }
         )