CanCanCan : Use differnt column to `load_and_authorize_resource` in inherited controllers

Recently I came across a situation where there was a need to use differnt column for load_and_authorize_resource in an inherited controller.

By default CanCanCan, use id to find resources in load_and_authorize_resource

If you want to use different column, you can use :find_by option:

load_and_authorize_resource :find_by => :slug

But this will apply on all the controller inheriting it.

# app/controllers/application_controller.rb

class ApplicationController < ActionController::Base

  load_and_authorize_resource

end

# app/controllers/posts_controller.rb
class PostsController < ApplicationController

  # for this controller, resource will be load using `id` 

end

If you try to put load_and_authorize_resource :find_by => :slug in posts_controller.rb hoping it will override the behaviour then you are wrong. It doesn’t work.

To make it working, you need to use :prepend option.

# app/controllers/posts_controller.rb
class PostsController < ApplicationController

  load_and_authorize_resource :find_by => :slug, prepend: true

end

Hope this helps!