“undefined method” when calling helper method from controller in Rails

Question

Does anyone know why I get

undefined method `my_method\' for #

when I call my_method(\"string\") from withi

Answer 1

Include ApplicationHelper in application_controller.rb file like this:

class ApplicationController < ActionController::Base
  protect_from_forgery       
  include ApplicationHelper  
end

This way all the methods defined in application_helper.rb file will be available in the controller.

You can also include individual helpers in individual controllers.

Answer 2

Try this to access helper function directly from your controllers view_context.helper_name

Answer 3

As said by gamecreature in this post:

• In Rails 2 use the @template variable.
• In Rails 3 use the controller method view_context

Answer 4

I had the same problem...

you can hack/bodge around it, put that logic into a model, or make a class specially for it. Models are accessible to controllers, unlike those pesky helper methods.

Here is my "rag.rb" model

class Rag < ActiveRecord::Base
  belongs_to :report
  def miaow()
    cat = "catattack"
  end  
end

Here is part of my "rags_controller.rb" controller

def update
  @rag = Rag.find(params[:id])
  puts @rag.miaow()
  ...

This gave a catattack on the terminal, after I clicked "update".

Given an instantiation, methods in the model can be called. Replace catattack with some codes. (This is the best I have so far)

:helper all only opens helpers up to views.

This shows how to make a class and call it. http://railscasts.com/episodes/101-refactoring-out-helper-object?autoplay=true

Answer 5

though its not a good practice to call helpers in controller since helpers are meant to be used at views the best way to use the helpers in controller is to make a helper method in application_controller and call them to the controller,
but even if it is required to call the helper in a controller
then Just include the helper in the controller

class ControllerName < ApplicationController
  include HelperName
  ...callback statements..

and call the helper methods directly to the controller

 module OffersHelper
  def generate_qr_code(text)
    require 'barby'
    require 'barby/barcode'
    require 'barby/barcode/qr_code'
    require 'barby/outputter/png_outputter'
    barcode = Barby::QrCode.new(text, level: :q, size: 5)
    base64_output = Base64.encode64(barcode.to_png({ xdim: 5 }))
    "data:image/png;base64,#{base64_output}"
  end

Controller

class ControllerName < ApplicationController
include OffersHelper

def new
  generate_qr_code('Example Text')
end
end

hope this helps !