Support null in content PATCH to delete a field value #187

CHANGES.rst

@@ -4,7 +4,9 @@ Changelog
 1.3.1 (unreleased)
 ------------------
 
-- Nothing changed yet.
+- Support null in content PATCH requests to delete a field value
+  (dexterity only). Fixes #187.
+  [csenger]
 
 
 1.3.0 (2018-03-05)

docs/source/content.rst

@@ -176,7 +176,13 @@ Updating a Resource with PATCH
 ------------------------------
 
 To update an existing resource we send a PATCH request to the server.
-PATCH allows to provide just a subset of the resource (the values you actually want to change):
+PATCH allows to provide just a subset of the resource
+(the values you actually want to change).
+
+If you send the value ``null`` for a field, the field's content will be
+deleted and the ``missing_value`` defined for the field in the schema
+will be set. Note that this is not possible if the field is ``required``,
+and it only works for Dexterity types, not Archetypes:
 
 ..  http:example:: curl httpie python-requests
     :request: _json/content_patch.req

src/plone/restapi/deserializer/dxcontent.py

@@ -62,6 +62,21 @@ def __call__(self, validate_all=False, data=None):  # noqa: ignore=C901
                     if not self.check_permission(write_permissions.get(name)):
                         continue
 
+                    # set the field to missing_value if we receive null
+                    if data[name] is None:
+                        if not field.required:
+                            dm.set(field.missing_value)
+                        else:
+                            errors.append({
+                                'field': field.__name__,
+                                'message': (
+                                    '{} is a required field.'.format(
+                                        field.__name__
+                                    ),
+                                    'Setting it to null is not allowed.'
+                                )})
+                        continue
+
                     # Deserialize to field value
                     deserializer = queryMultiAdapter(
                         (field, self.context, self.request),

src/plone/restapi/tests/dxtypes.py

@@ -118,6 +118,13 @@ class IDXTestDocumentSchema(model.Schema):
     test_invariant_field1 = schema.TextLine(required=False)
     test_invariant_field2 = schema.TextLine(required=False)
 
+    test_missing_value_field = schema.TextLine(required=False,
+                                               missing_value=u'missing',
+                                               default=u'default')
+
+    test_missing_value_required_field = schema.TextLine(
+        required=True, missing_value=u'missing', default=u'some value')
+
     @invariant
     def validate_same_value(data):
         if data.test_invariant_field1 != data.test_invariant_field2:

src/plone/restapi/tests/test_content_patch.py

@@ -27,7 +27,8 @@ def setUp(self):
         self.portal.invokeFactory(
             'Document',
             id='doc1',
-            title='My Document'
+            title='My Document',
+            description='Some Description'
         )
         wftool = getToolByName(self.portal, 'portal_workflow')
         wftool.doActionFor(self.portal.doc1, 'publish')
@@ -44,6 +45,41 @@ def test_patch_document(self):
         transaction.begin()
         self.assertEqual("Patched Document", self.portal.doc1.Title())
 
+    def test_patch_document_will_delete_value_with_null(self):
+        self.assertEqual(self.portal.doc1.description, 'Some Description')
+        response = requests.patch(
+            self.portal.doc1.absolute_url(),
+            headers={'Accept': 'application/json'},
+            auth=(SITE_OWNER_NAME, SITE_OWNER_PASSWORD),
+            data='{"description": null}',
+        )
+        transaction.commit()
+
+        # null will set field.missing_value which is u'' for the field
+        self.assertEqual(204, response.status_code)
+        self.assertEqual(u'', self.portal.doc1.description)
+
+    def test_patch_document_will_not_delete_value_with_null_if_required(self):
+        response = requests.patch(
+            self.portal.doc1.absolute_url(),
+            headers={'Accept': 'application/json'},
+            auth=(SITE_OWNER_NAME, SITE_OWNER_PASSWORD),
+            data='{"title": null}',
+        )
+        transaction.commit()
+
+        # null will set field.missing_value which is u'' for the field
+        self.assertEqual(400, response.status_code)
+        self.assertTrue("\'field\': \'title\'" in response.text)
+        self.assertTrue(
+            'title is a required field.'
+            in response.text
+        )
+        self.assertTrue(
+             'Setting it to null is not allowed.'
+             in response.text
+        )
+
     def test_patch_document_with_representation(self):
         response = requests.patch(
             self.portal.doc1.absolute_url(),

src/plone/restapi/tests/test_dxcontent_deserializer.py

@@ -162,6 +162,30 @@ def test_deserializer_passes_validation_with_not_provided_defaults(self):
         self.assertEquals(u'DefaultFactory',
                           self.portal.doc1.test_default_factory_field)
 
+    def test_deserializer_sets_missing_value_when_receiving_null(self):
+        self.deserialize(body='{"test_missing_value_field": null}')
+        self.assertEquals(u'missing',
+                          self.portal.doc1.test_missing_value_field)
+
+    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"}')
+        with self.assertRaises(BadRequest) as cm:
+            self.deserialize(
+                body='{"test_missing_value_required_field": null}')
+        self.assertEquals(u'valid value',
+                          self.portal.doc1.test_missing_value_required_field)
+        self.assertEquals(
+            (
+                'test_missing_value_required_field is a required field.',
+                'Setting it to null is not allowed.'
+            ),
+            cm.exception.message[0]['message']
+        )
+        self.assertEquals(u'test_missing_value_required_field',
+                          cm.exception.message[0]['field'])
+
     def test_set_layout(self):
         current_layout = self.portal.doc1.getLayout()
         self.assertNotEquals(current_layout, "my_new_layout")