Forum: Ruby on Rails Recommended way of restricting action permissions?

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Lisa Klein (Guest)
on 2008-12-19 22:26
(Received via mailing list)
Hi, I just have a "best practices" question.  I'd like to block users
that don't own a particular resource from performing edit/update/
destroy actions on it.  Here's how I currently do it:

## User has many resources, of different types

------- resource_controller.rb -------

before_filter :require_ownership, :only => [:edit, :update, :destroy]

... public actions ...

protected

def require_ownership
  @resource = Resource.find(params[:id])
  redirect_to_somewhere unless owns?(@resource)
end

------- application.rb -------

def owns?(resource)
  resource.user_id == @current_user.id
end

... And I apply this before_filter in the controller of any resource
I'd like to restrict in a similar way.  I'm new to Rails and MVC so
I'm just wondering whether this is the best way of accomplishing this,
or if a different method is recommended.

Thanks in advance!
Darrik Mazey (Guest)
on 2008-12-19 22:26
(Received via mailing list)
Ms. Klein,

I handle that situation very similarly with the only disparity being
where ownership is determined.  In my opinion the object itself should
know nothing about @current_user, whereas the application can know about
Resource.user.

I also tend to alias methods in my resources, like so

def self.owner
  self.user
end

Then I insure that every object has some owner alias if it is to be
restricted, and in my :require_ownership before_filter, I do the
following:

def require_ownership
  if @resource.owner == @current.user ...
end

The end effect is the same, but this allows the resource to be used
intact in another application without modification, regardless of
@current_user in the other application.  Just of matter of who knows
what about whom.

Otherwise, unless someone can suggest a better method for us both, I
personally think you're on the right track.

Cheers,
Darrik Mazey


Lisa Klein wrote:
> ... public actions ...
> def owns?(resource)
>
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Darrik Mazey
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Maurício L. (Guest)
on 2008-12-19 22:32
(Received via mailing list)
The simpler way is just search the user resources when performing an
edit/update/delete. like this:

def edit
  @resource = @user.resources.find(params[:id])
end

This way you can be sure that the user will not be able to select a
resource that doesn't belong to him.

-
Maurício Linhares
http://alinhavado.wordpress.com/ (pt-br) | http://blog.codevader.com/
(en)
Lisa Klein (Guest)
on 2008-12-19 22:38
(Received via mailing list)
Thanks a lot for the replies!  I guess I kind of prefer the
before_filter method a little bit because then I don't have to
replicate the redirect_if_not_found logic in each restricted action.
Thanks again!
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