Rails: how to RESTful query models through associations?

Question

I'm not getting REST with Ruby on Rails, and I'm hoping someone here can set me straight. Imagine that I'm building a site that keeps track of Widgets and the Users that own those Widgets. So I'd have a UsersController and a WidgetsController, and I could get a list of Widgets or Users with the index actions: ``` GET /users GET /widgets ``` and I could get a specific User or Widget with the show actions: ``` GET /users/id GET /widgets/id ``` That much I understand. Where I'm getting confused is what RESTful request would I use to retrieve a list of Widgets belonging to a specific User? Is that a request sent to the UsersController or the WidgetsController? Which of the 7 RESTful actions does it use? Is one of those situations where I'd create a custom action? I was under the impression that custom actions are supposed to be rare, but this seems like a pretty common use case. Thanks!

Accepted Answer

The url for the list of widgets belonging to a user `foo` would look like this:

```
/users/foo/widgets
```

You then have a choice of how to do your URLs for each of those widgets. This is possible:

```
/users/foo/widgets/bar
```

But I prefer this:

```
/widgets/bar
```

Your routes would look like this:

```
map.resources :users, :has_many => :widgets, :shallow => true
map.resources :widgets, :has_many => :users, :shallow => true
```

(This is from memory, I may have screwed up one or more details)

The controller method that handles `/user/foo/widgets` is the `index` action of the `WidgetController`. It tests for the existence of the `user_id` parameter and restricts the widgets returned based on that. (Or retrieves the `foo` user and sets `@widgets` to `@user.widgets`.)

Update: There's a good overview of nested routing that answers my original question in the Rails Guides.

Update 2 Oh yes, I meant to link to some documentation as well.

Rails: how to RESTful query models through associations?

Solution

Problem