feat(api): Add back url to metadata

ref: #410 #411

app/api/react_ui_metadata.py

@@ -90,6 +90,10 @@ def determine_metadata(self, request, view):
 
             metadata['urls'].update({'self': url_self})
 
+        if view.get_back_url():
+
+            metadata['urls'].update({'back': view.get_back_url()})
+
         if view.get_return_url():
 
             metadata['urls'].update({'return_url': view.get_return_url()})

app/api/viewsets/common.py

@@ -82,6 +82,25 @@ def allowed_methods(self):
 
     view_name: str = None
 
+    def get_back_url(self) -> str:
+        """Metadata Back URL
+
+        This URL is an optional URL that if required the view must
+        override this method. If the URL for a back operation
+        is not the models URL, then this method is used to return
+        the URL that will be used.
+
+        Defining this URL will predominatly be for sub-models. It's
+        recommended that the `reverse` function
+        (rest_framework.reverse.reverse) be used with a `request`
+        object.
+
+        Returns:
+            str: Full url in format `<protocol>://<doman name>.<tld>/api/<API version>/<model url>`
+        """
+
+        return None
+
 
     def get_model_documentation(self):