How to call ApplicationController methods from ApplicationHelper

问题

I want to provide csv links in a view and I placed the csv generating code in ApplicationHelper. However I'm getting this error:

undefined method `send_data' for #<#<Class:0x0000010151c708>:0x0000010151a070>

referencing this:

send_data content, :type => "text/plain",
  :filename => filename,
  :disposition => 'attachment'

If I place the csv code in a controller it works fine. I was hoping to use the helper to avoid having to define routes for every controller I want to provide csv options for (I have a bunch). How can I make send_data (and other necessary methods) available to the helper?

回答1:

Use helper_method.

By default, methods in ApplicationController are only accessible inside the Controllers.

Add a method to the ApplicationController and expose it as a helper method with helper_method:

class ApplicationController < ActionController::Base

  helper_method :foo

  def foo
    "bar"
  end

end

Now the foo method is accessible to both Controllers and Views.

回答2:

If the issue is to make methods in ApplicationHelper available in all controllers, why not add a line

include ApplicationHelper

to the ApplicationController file?

来源：https://stackoverflow.com/questions/5985761/how-to-call-applicationcontroller-methods-from-applicationhelper