REST API nested resources should be handled by which controller?

Question

Let's say I have a REST API endpoint: users/123/orders/234.

As the URI implies, I am returning order 234 for user 123. My question is, which controller should handle the request?

Should it be an action in the UsersController, something like GetOrder(int userId, int orderId)? Or should it be handled in the OrdersController with something like GetOrder(int id)?

Is it just a matter of taste, or is one way more "correct" than the other?

Answer 1

Well I would advocate you should go by the entity that is being fetched.

In your case What is being fetched? : Orders -> So OrdersController.

If Users were being fetched given a particular order id then it would be a UsersController.

You should have a look at the stackexchange api for good examples : http://api.stackexchange.com/docs

There are numerous actions, but they're each grouped by the entity they operate on, and I bet that's the controller they are in.

---

There is no inbuilt setup for this route. You could do the following :

This is a specific route.

routes.MapHttpRoute(
    name: "users_orders",
    routeTemplate: "api/{controller}/{user_id}/Orders/{order_id}",
    defaults: new
    {
        controller = "Orders",
        action = "FetchByUser"
    });

Which would need an action method like this:

public ActionResult FetchByUser(int user_id, int order_id)
{
}

You could try doing a more generalised route like this:

routes.MapHttpRoute(
    name: "fetch_route",
    routeTemplate: "api/{controller}/{id1}/{type}/{id2}",
    defaults: new
    {
        action = "Fetch"
    });

And the action method would be:

public ActionResult Fetch(int user_id, string type, int order_id)
{
}

Note: I would interpret this -> users/123/orders/234 as for the user 123 get the order 234. If like @karan says you don't need the user context then you should not have this method. I'm not sure about your design or requirements here.