For a while, I have felt that the following is the correct way to improve the mass assignment problem without increasing the burden on new users. Now that the problem with the Rails default has been brought up again, it's a good time to revisit it.
When creating a form with form_for
, include a signed token including all of the fields that were created at form creation time. Only these fields are allowed.
To allow new known fields to be added via JS, we could add:
<%= f.allowed_fields "foo", "bar", "baz" %>
The first strategy will not full satisfy apps that support a lot of HTTP requests that do not come from forms generated by Rails.
Because accessible fields is usually a function of authorization, and is not global, we should move allowed fields into the controller. The basic idea is:
class PostsController < ApplicationController
# attributes can be marked accessible for the entire controller
attr_accessible :foo, :bar
def create
# mass assignment can also be done on an instance basis
# this can be used to override the class defaults
attr_accessible(true) if user.admin?
...
end
end
I would imagine that Rails authorization frameworks like CanCan could add sugar to make this even easier in common cases.
The core problem with Rails mass assignment is that attribute protection is an authorization concern. By moving it to the controller, we can have smart defaults (like signed fields in form_for
) and in more advanced cases, make it easier to decide what fields are allowed on a per-user basis.
By moving it into the correct place, we will probably find other nice abstractions that we can use over time to make nice defaults for users without compromising security.
@bradphelan sorry, guy, after all the work of yours writing that comment, it can all be chopped down to:
Where CanCan helps you like this:
There is no need for this at all:
I mean, that can be already done today. But we hate having to write a different controller and authorization rule for each attribute, that's why we resort to update_attributes. So, you are right in that you are proposing best practices, but the result is long and boring, and Rails should provide a way to make it short and beautiful, I guess.
My vote goes for a new layer that underlines the difference between model and resource, also allowing for multiple models exposed as a single resource. And no, @oelmekki, I haven't written any code yet. I just got the idea yesterday, but I also wouldn't have the time, sorry.