Fix relatedItems [null] for deleted relations

news/965.bugfix

@@ -0,0 +1 @@
+Return empty list for relatedItems when related content was deleted instead of [null]. Filter broken relations in RelationListFieldSerializer.get_value() by to_object so only resolvable relations are serialized. @aryan7081

src/plone/restapi/serializer/relationfield.py

@@ -44,7 +44,9 @@ def get_value(self, default=None):
         """
         value = super().get_value()
         if value:
-            return [el for el in value if el.to_id]
+            # Only include relations that still resolve (skip broken relations
+            # e.g. when the target content was deleted). Avoids [null] in JSON.
+            return [el for el in value if el.to_object]
         if default is None:
             return []
         return default

src/plone/restapi/tests/test_content_get.py

@@ -179,6 +179,23 @@ def test_get_content_related_items_without_workflow(self):
             response.json()["relatedItems"],
         )
 
+    def test_get_content_related_items_returns_empty_list_when_related_deleted(self):
+        """When a related item is deleted, REST API should return [] not [null]."""
+        intids = getUtility(IIntIds)
+        self.portal.folder1.folder2.doc2.relatedItems = [
+            RelationValue(intids.getId(self.portal.folder1.doc1))
+        ]
+        transaction.commit()
+        self.portal.folder1.manage_delObjects(["doc1"])
+        transaction.commit()
+        response = requests.get(
+            self.portal.folder1.folder2.doc2.absolute_url() + "?fullobjects",
+            headers={"Accept": "application/json"},
+            auth=(SITE_OWNER_NAME, SITE_OWNER_PASSWORD),
+        )
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.json().get("relatedItems"), [])
+
 
 class TestBlocksContentGet(unittest.TestCase):
     layer = PLONE_RESTAPI_BLOCKS_FUNCTIONAL_TESTING