Override a Rails Engine controller action

Question

i'm using a Rails engine, but i need to customize some controllers actions.

I actually forked the engine, and implementing those customizations into my own fork, but i was wondering if there is an official way in Rails Engines to override and customize controllers.

Have a look there http://stackoverflow.com/questions/5045068/extending-controllers-of-a-rails-3-engine-in-the-main-app — Andrei, Feb 19 '11 at 14:36

nathanvda · Accepted Answer · 2013-08-21T23:19:12.840

21

Just define a controller with the same name in your own app\controllers folder, and it will be found first. That way you can easily customize it.

Please note: because it is found first, you replace the entire controller from the engine. This could be exactly what you want. In some cases, you just want to adjust a little, then it is much better to reopen the class, and only redefine what is needed.

Examples to do is can be found here: http://edgeguides.rubyonrails.org/engines.html#overriding-models-and-controllers

edited Aug 21 '13 at 23:19

answered May 21 '10 at 10:18

nathanvda

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A lot easier than maintaing a custom fork! Thanks and sorry for the lame question! – Marco Borromeo May 21 '10 at 10:40
This will override the entire controller, not just one action. – Brad Werth Jan 31 '13 at 20:40
I didn't claim otherwise. But at least you can customize it. Do you have a better solution? – nathanvda Feb 01 '13 at 19:04
There are several, of which this seems to be the preferred method - http://edgeguides.rubyonrails.org/engines.html#overriding-models-and-controllers – Brad Werth Aug 21 '13 at 22:30
Thanks, I adapted my answer accordingly. – nathanvda Aug 21 '13 at 23:19

score 13 · Answer 2 · answered Apr 28 '17 at 22:26

The link in the accepted answer does not actually provide an example to overriding a controller. They mention "open classing" the file, but don't explain how exactly to do it. If you open the engine class in your app, you will get a circular dependency error because you are referencing/opening a class that is currently in the process of being defined. Therefore, you need to make sure you load the engine's actual class first.

# in my app
# app/controllers/blazer/base_controller.rb
load Blazer::Engine.root.join('app/controllers/blazer/base_controller.rb')
Blazer::BaseController.class_eval do
  filter_access_to :all
end

In my case, I'm using the Blazer gem and adding authentication to it. Since I use declarative authorization, which Blazer does not directly support, I need to open up Blazer's base controller and add my authorization requirement to it.

This should be the accepted answer since it gives an example of what the OP was asking for as well uses format the docs in the rails guide suggest. — dft, Oct 25 '17 at 20:18
@DavidT I believe so. I see this all over in gems that produce engines. — Peter P., Nov 03 '18 at 00:39

Override a Rails Engine controller action

2 Answers2