Rails 4 Use Application Helpers Inside Initializers

rails 4 use application helpers inside initializers

This is one way to do it:

# lib/browser_util.rb
module BrowserUtil
  def self.supported?(browser)
    # your code ...
  end
end

and wrap that from ApplicationHelper for use in views

module ApplicationHelper
  def is_browser_supported?
    BrowserUtil.supported?(browser)
  end
end

in middleware

Rails.configuration.middleware.use Browser::Middleware do
  unless BrowserUtil.supported?(browser)
    redirect_to :controller => 'error', :action => 'browser-upgrade-required' 
  end
end

UPDATE: it does not need to be in a separate module (BrowserUtil)

module ApplicationHelper
  def self.foo
    "FOO"
  end

  def foo
    ApplicationHelper.foo
  end
end

in middleware use

ApplicationHelper.foo

in views it would use the included method

foo

Accessing helpers and models from rails engine initializer

After I used required for every class, I ended with ActiveRecord::ConnectionNotEstablished, and it seems that not everything is loaded and available at that point when the GLOBAL object is created.

So I moved the code that was using the models in a separate init method. Then, I added an after initialize event:

  config.after_initialize do
    MyEngine.GLOBAL.init
  end

How to run an initializer that calls Rails.application?

According to The Rails Initialization Process of the Rails official reference, the last file to be executed in the initialization sequence is config/environment.rb (Note that although the reference states the last one is config/application.rb, the file should have been in default require-d in the earlier process).

In Rails 6 (or maybe earlier ones, too?), the last line in config/environment.rb is

Rails.application.initialize!

So, if you write your own statements after the line in the file config/environment.rb, your Rails app must have been fully initialized by the time your statements are executed.

The reason why it's possible to use helper method like current_user, authenticate_user!, and so on without including any module

The answer is devise included its helper methods into ActionController on behalf of you when Rails on_load

# devise/rails.rb
module Devise
  class Engine < ::Rails::Engine
    # ...
    initializer "devise.url_helpers" do
      Devise.include_helpers(Devise::Controllers)
    end
    # ...
end

# devise.rb
  # ...
  def self.include_helpers(scope)
    ActiveSupport.on_load(:action_controller) do
      include scope::Helpers if defined?(scope::Helpers)
      include scope::UrlHelpers
    end

    ActiveSupport.on_load(:action_view) do
      include scope::UrlHelpers
    end
  end
  # ...   

I saw many 3rd gems using on_load to include their methods (or themselves) into Rails core, maybe it's a typical way to do that (allows Rails to lazily load a lot of components and thus making the app boot faster). If you install some gems and you could use their methods on your model/controller/view then those gems did the same thing devise did above.

About those methods current_user, authenticate_user! ... they are dynamic methods devise will generate when it did include scope::Helpers into Rails (see code above and the link).

Accessing helpers from the parent app in an isolated Rails engine

The RailsAdmin Engine is also isolated, but they have the same configuration options as you would like to implement. They have configurable before_filters for both authentication and authorization. Have a look at this.

As far as I can tell, they just subclass the parent controller like this::ApplicationController or instead you can configure one (ref).

For your controller you could just create your own EngineController, that inherits from RocketPant::Base and maybe just create a method there that calls the configured authentication method directly via send on the parent controller.

As the RocketPant::Base Class does not inherit from ApplicationController::Base I guess you have to find some custom way around this and can't go the normal ways for Rails Engines. Maybe you could also try to file an issue to the rocket_pant repo, to add the helper method. As far as I read they soon want to inherit from ApplicationController::Base anyway in 2.0 (ref).

Strange Missing Helper File Error in Rails

Seems the helper file has been deleted at some stage.

In the helpers folder create a new file, rename it underwrite.rb and place the following code inside it.

module UnderwriteHelper
end

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