This code is after moving logic to model

gistfile1.rb

class CommentsController < ApplicationController
  def create
    Comment.create(params[:comment])
    render :text => 'Success'
  end
end

#################################################

class Comment < ActiveRecord::Base
  belongs_to :event_user
  attr_accessible :text, :event_user
  delegate :uid, to: 'event_user.user'

  after_create do
    FayeClient.broadcast("/event_#{event_user.event_id}_comments", as_json)
  end

  def as_json
    super.merge(uid: uid, text: ERB::Util.html_escape(text))
  end
end