Revisit improve support for zope.schema default and missing_value if present

news/1282.bugfix

@@ -0,0 +1,2 @@
+Improve support and meaning for `default` and `missing_value` in serializers/deserializers
+[sneridagh]

src/plone/restapi/deserializer/dxcontent.py

@@ -76,7 +76,7 @@ def __call__(
 
         return self.context
 
-    def get_schema_data(self, data, validate_all, create=False):
+    def get_schema_data(self, data, validate_all, create=False):  # noqa: ignore=C901
         schema_data = {}
         errors = []
 
@@ -159,6 +159,43 @@ def get_schema_data(self, data, validate_all, create=False):
                     if name == "changeNote":
                         continue
                     dm = queryMultiAdapter((self.context, field), IDataManager)
+
+                    # Covering here default/missing_value edge cases
+                    if (
+                        create
+                        and name not in data
+                        and (
+                            dm.field.defaultFactory is not None
+                            or field.default is not None
+                        )
+                        and not field.required
+                    ):
+                        # precondition:
+                        # - On creation
+                        # - name was not handled before
+                        # - not required, otherwise there has to be a value
+                        # - one of defaultFactory or default are defined, so at least one of them can be set
+                        if dm.field.defaultFactory:
+                            dm.set(dm.field.defaultFactory(self.context))
+                            self.mark_field_as_changed(schema, name)
+                        elif field.default:
+                            dm.set(field.default)
+                            self.mark_field_as_changed(schema, name)
+                    elif (
+                        name not in data
+                        and field.missing_value is not None
+                        and not field.required
+                    ):
+                        # precondition:
+                        # - name was not handled before
+                        # - not required, otherwise there has to be a value
+                        # - missing_value is defined, so it can be set
+                        dm_value = dm.get()
+                        if dm_value is None:
+                            # if there's no value at all currently in the object
+                            # then it sets the missing value
+                            dm.set(field.missing_value)
+
                     bound = field.bind(self.context)
                     try:
                         bound.validate(dm.get())

src/plone/restapi/tests/dxtypes.py

@@ -279,6 +279,10 @@ class IDXTestDocumentSchema(model.Schema):
         required=False, missing_value="missing", default="default"
     )
 
+    test_missing_value_field_and_no_default = schema.List(
+        required=False, value_type=schema.Choice(values=[1, 2, 3]), missing_value=[]
+    )
+
     test_missing_value_required_field = schema.TextLine(
         required=True, missing_value="missing", default="some value"
     )

src/plone/restapi/tests/http-examples/content_get.resp

@@ -38,7 +38,10 @@ Content-Type: application/json
     "expires": null,
     "id": "my-document",
     "is_folderish": false,
-    "language": "",
+    "language": {
+        "title": "English",
+        "token": "en"
+    },
     "layout": "document_view",
     "lock": {
         "locked": false,

src/plone/restapi/tests/http-examples/content_patch_representation.resp

@@ -38,7 +38,10 @@ Content-Type: application/json
     "expires": null,
     "id": "my-document",
     "is_folderish": false,
-    "language": "",
+    "language": {
+        "title": "English",
+        "token": "en"
+    },
     "layout": "document_view",
     "lock": {
         "locked": false,

src/plone/restapi/tests/http-examples/content_post.resp

@@ -39,7 +39,10 @@ Location: http://localhost:55001/plone/folder/my-document
     "expires": null,
     "id": "my-document",
     "is_folderish": false,
-    "language": "",
+    "language": {
+        "title": "English",
+        "token": "en"
+    },
     "layout": "document_view",
     "lock": {
         "locked": false,

src/plone/restapi/tests/test_dxcontent_deserializer.py

@@ -186,6 +186,44 @@ def test_deserializer_sets_missing_value_when_receiving_null(self):
         self.deserialize(body='{"test_missing_value_field": null}')
         self.assertEqual("missing", self.portal.doc1.test_missing_value_field)
 
+    def test_deserializer_sets_missing_value_when_receiving_nothing_at_all(self):
+        # If the field is not set in the request data, it has no value set either, nor default,
+        # and missing_value is defined, it sets the missing value
+        self.deserialize(body='{"test_required_field": "My Value"}', validate_all=True)
+        self.assertEqual([], self.portal.doc1.test_missing_value_field_and_no_default)
+
+    def test_deserializer_has_default_and_missing_value_sets_default_when_receiving_nothing_at_all(
+        self,
+    ):
+        # If the field is not set in the request data, it has a default
+        # and a missing_value defined, it sets nothing, thus Dexterity returns default on validation
+        self.deserialize(body='{"test_required_field": "My Value"}', validate_all=True)
+        self.assertEqual("default", self.portal.doc1.test_missing_value_field)
+
+    def test_deserializer_on_conflictive_field_language(self):
+        """In the wild, there are conflictive field declarations that has both a default and
+        a missing_value set, that in some cases the deserializer when values are missing in the
+        request. Handling default nullish values is hard."""
+        self.portal.invokeFactory(
+            "Document",
+            id="doc_language",
+        )
+        self.deserialize(
+            body='{"title": "The title"}',
+            context=self.portal["doc_language"],
+            validate_all=True,
+            create=True,
+        )
+        self.assertEqual("en", self.portal.doc_language.language)
+
+        self.deserialize(
+            body='{"title": "The title", "language": "en"}',
+            context=self.portal["doc_language"],
+            validate_all=True,
+            create=True,
+        )
+        self.assertEqual("en", self.portal.doc_language.language)
+
     def test_deserializer_sets_missing_value_on_required_field(self):
         """We don't set missing_value if the field is required"""
         self.deserialize(body='{"test_missing_value_required_field": "valid value"}')

src/plone/restapi/tests/test_dxcontent_serializer.py

@@ -150,6 +150,16 @@ def test_serializer_includes_field_with_read_permission(self):
         self.assertIn("test_read_permission_field", obj)
         self.assertEqual("Secret Stuff", obj["test_read_permission_field"])
 
+    def test_serializer_includes_default_value(self):
+        obj = self.serialize()
+        self.assertIn("test_missing_value_field", obj)
+        self.assertEqual("default", obj["test_missing_value_field"])
+
+    def test_serializer_returns_None_if_only_missing_value_is_present(self):
+        obj = self.serialize()
+        self.assertIn("test_missing_value_field_and_no_default", obj)
+        self.assertEqual(None, obj["test_missing_value_field_and_no_default"])
+
     def test_get_layout(self):
         current_layout = self.portal.doc1.getLayout()
         obj = self.serialize()