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Rails - How to use a Helper Inside a Controller

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Can we use helper method in controller Rails?

In Rails 5, by using the new instance level helpers method in the controller, we can access helper methods in controllers.

How do helpers work in Rails?

A helper is a method that is (mostly) used in your Rails views to share reusable code. Rails comes with a set of built-in helper methods. One of these built-in helpers is time_ago_in_words . This method is helpful whenever you want to display time in this specific format.


You can use

  • helpers.<helper> in Rails 5+ (or ActionController::Base.helpers.<helper>)
  • view_context.<helper> (Rails 4 & 3) (WARNING: this instantiates a new view instance per call)
  • @template.<helper> (Rails 2)
  • include helper in a singleton class and then singleton.helper
  • include the helper in the controller (WARNING: will make all helper methods into controller actions)

Note: This was written and accepted back in the Rails 2 days; nowadays grosser's answer is the way to go.

Option 1: Probably the simplest way is to include your helper module in your controller:

class MyController < ApplicationController
  include MyHelper

  def xxxx
    @comments = []
    Comment.find_each do |comment|
      @comments << {:id => comment.id, :html => html_format(comment.content)}
    end
  end
end

Option 2: Or you can declare the helper method as a class function, and use it like so:

MyHelper.html_format(comment.content)

If you want to be able to use it as both an instance function and a class function, you can declare both versions in your helper:

module MyHelper
  def self.html_format(str)
    process(str)
  end

  def html_format(str)
    MyHelper.html_format(str)
  end
end

Hope this helps!


In Rails 5 use the helpers.helper_function in your controller.

Example:

def update
  # ...
  redirect_to root_url, notice: "Updated #{helpers.pluralize(count, 'record')}"
end

Source: From a comment by @Markus on a different answer. I felt his answer deserved it's own answer since it's the cleanest and easier solution.

Reference: https://github.com/rails/rails/pull/24866


My problem resolved with Option 1. Probably the simplest way is to include your helper module in your controller:

class ApplicationController < ActionController::Base
  include ApplicationHelper

...