Add test to check deleted relations

src/plone/restapi/serializer/relationfield.py

@@ -7,7 +7,6 @@
 from z3c.relationfield.interfaces import IRelationChoice
 from z3c.relationfield.interfaces import IRelationList
 from z3c.relationfield.interfaces import IRelationValue
-from z3c.relationfield import RelationValue
 from zope.component import adapter
 from zope.component import getMultiAdapter
 from zope.globalrequest import getRequest
@@ -48,6 +47,4 @@ def get_value(self, default=[]):
         )
         if not value:
             return []
-        if isinstance(value, RelationValue):
-            return [value]
         return [el for el in value if el.to_object]

src/plone/restapi/tests/test_dxcontent_serializer.py

@@ -27,6 +27,9 @@
 from zope.component import provideAdapter
 from zope.component import queryUtility
 from zope.interface import Interface
+from z3c.relationfield import RelationValue
+from zope.component import getUtility
+from zope.intid.interfaces import IIntIds
 from zope.publisher.interfaces.browser import IBrowserRequest
 from importlib import import_module
 
@@ -191,6 +194,26 @@ def test_serializer_includes_expansion(self):
             "foo",
         )
 
+    def test_serializer_excludes_deleted_relations(self):
+
+        intids = getUtility(IIntIds)
+        self.portal.invokeFactory(
+            "DXTestDocument",
+            id="doc2",
+        )
+        self.portal.doc1.test_relationlist_field = [
+            RelationValue(intids.getId(self.portal.doc1)),
+            RelationValue(intids.getId(self.portal.doc2)),
+        ]
+        # delete doc2 to make sure we have a None value in the relation list
+        self.portal.manage_delObjects(["doc2"])
+
+        obj = self.serialize()
+        self.assertEqual(1, len(obj["test_relationlist_field"]))
+        self.assertEqual(
+            "http://nohost/plone/doc1", obj["test_relationlist_field"][0]["@id"]
+        )
+
     def test_get_is_folderish(self):
         obj = self.serialize()
         self.assertIn("is_folderish", obj)