My app should render html, to answer when a user clicks ajax-link.

My controller:

def create_user
  @user = User.new(params)
  if @user.save
    status = 'success'
    link = link_to_profile(@user) #it's my custom helper in Application_Helper.rb
  else
    status = 'error'
    link = nil
  end

  render :json => {:status => status, :link => link}
end

My helper:

  def link_to_profile(user)
    link = link_to(user.login, {:controller => "users", :action => "profile", :id => user.login}, :class => "profile-link")
    return(image_tag("/images/users/profile.png") + " " + link)
  end

I have tried such methods:

ApplicationController.helpers.link_to_profile(@user)
# It raises: NoMethodError (undefined method `url_for' for nil:NilClass)

and:

class Helper
  include Singleton
  include ApplicationHelper
  include ActionView::Helpers::TextHelper
  include ActionView::Helpers::UrlHelper
  include ApplicationHelper
end
def help
  Helper.instance    
end

help.link_to_profile(@user)
# It also raises: NoMethodError (undefined method `url_for' for nil:NilClass)

In addition, yes, I KNOW about :helper_method, and it works, but i don't want to overload my ApplicationController with a plenty of that methods