On 20 Aug 2011, at 13:35, Stan McFarland wrote:
> If I have a basic HABTM association - say, users and groups - I can't
> get my head around the RESTful routing required to add a user to a
> group.
>
> POST /user will call user#create
> POST /group will call group#create
> POST /group/:group_id/user should call: what? Is it ok to define
> a "addUser" action to the group controller? Or should I test for the
> existence of the group_id in the user#create method and then proceed
> accordingly? I want to do things the Rails way but sometimes my PHP
> experience comes back to haunt me. :)
There is no one 'correct' way to do this. Both of your suggestions will work.
But I'd agree with your instinct that they both feel a little bit hackish.
One solution would be to specify a different controller to handle users scoped
inside groups:
resources :groups do
resources :users, :controller => 'group_users'
end
Then the concept of creating a user inside a group, and the concept of creating
a user, can be handled in completely separate controllers.
The problem with this is that you'll be passing parameters like :user => {:name
=> "Bob Smith", :email => "[email protected]", …} to your UsersController, while
passing parameters like :user_id => 2 to your GroupUsersController. It feels
like theres some inconsistency there.
So you could invent a new concept, called a 'membership':
resources :groups do
resources :memberships
end
When a user joins a group, you're not really creating a user -- you're creating
a membership. When a user leaves a group, you're not really deleting a user --
you're deleting a membership.
Note that a resource doesn't have to match one-to-one with a database-backed
model. So you can expose this concept of a membership at your controller level,
and let the controllers deal with converting that to model talk:
POST '/groups/1/memberships', {:membership => {:user_id => 2}}
class MembershipsController < ActionController::Base
def create
@group = Group.find(params[:group_id])
@user = User.find(params[:membership][:user_id])
@group.users << @user
redirect_to wherever
end
end
Like I say, there isn't a 'correct' way of handling this kind of thing, but I
personally like the idea of exposing the semantics of your application like
this, and trying to think of things in terms of CRUD where possible.
Chris
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