How to catch exceptions in controller's actions properly?

Question

There is the following code:

def index
  @posts = User.find_by(login: params[:user_id]).posts
end

As you can see this code can generate exception if there is no user with some login (nil pointer exception). How can I catch this exception and handle it properly? I know how to catch exceptions in Ruby, but I want to know how to do in a good Rails style. The same problem may occur in different controllers - may be I should create an action wrapper, catch exception and render 500 error?

Answer 1

The easiest way is to use ApplicationController's rescue_from:

class ApplicationController < ActionController::Base
  rescue_from ActiveRecord::RecordNotFound, with: :record_not_found

  private

  def record_not_found
    render 'my/custom/template', status: 404
  end
end