How can I resolve NoMethodError using Ruby on rails?

Please Can anybody help me to resolve this following error.

Error

NoMethodError in PostsController#index

protected method `wp_parse_options' called for #<Class:0x1f26fc0>
Rails.root: C:/Site/datagem

Application Trace | Framework Trace | Full Trace
app/controllers/posts_controller.rb:7:in `index'

Please check my code snippets which are described below.

views/posts/index.html.erb

<%= form_tag posts_path, :method => 'get', :id => "posts_search" do %>
  <p>
    <%= text_field_tag :search, params[:search] %>
    <%= submit_tag "Search", :name => nil %>
  </p>
  <div id="posts"><%= render 'posts' %></div>
<% end %>

<%= link_to 'New Post', new_post_path %>

controller/posts_controller.rb

class PostsController < ApplicationController
  # GET /posts
  # GET /posts.json
  helper_method :sort_column, :sort_direction
  def index
    @posts = Post.all
    @posts = Post.search(params[:search]).order(sort_column + " " + sort_direction).paginate(:per_page => 5, :page => params[:page])
    respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @posts }
    end
  end

  # GET /posts/1
  # GET /posts/1.json
  def show
    @post = Post.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.json { render json: @post }
    end
  end

  # GET /posts/new
  # GET /posts/new.json
  def new
    @post = Post.new

    respond_to do |format|
      format.html # new.html.erb
      format.json { render json: @post }
    end
  end

  # GET /posts/1/edit
  def edit
    @post = Post.find(params[:id])
  end

  # POST /posts
  # POST /posts.json
  def create
    @post = Post.new(params[:post])

    respond_to do |format|
      if @post.save
        format.html { redirect_to @post, notice: 'Post was successfully created.' }
        format.json { render json: @post, status: :created, location: @post }
      else
        format.html { render action: "new" }
        format.json { render json: @post.errors, status: :unprocessable_entity }
      end
    end
  end

  # PUT /posts/1
  # PUT /posts/1.json
  def update
    @post = Post.find(params[:id])

    respond_to do |format|
      if @post.update_attributes(params[:post])
        format.html { redirect_to @post, notice: 'Post was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: "edit" }
        format.json { render json: @post.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /posts/1
  # DELETE /posts/1.json
  def destroy
    @post = Post.find(params[:id])
    @post.destroy

    respond_to do |format|
      format.html { redirect_to posts_url }
      format.json { head :no_content }
    end
  end
  private

  def sort_column
    Post.column_names.include?(params[:sort]) ? params[:sort] : "name"
  end

  def sort_direction
    %w[asc desc].include?(params[:direction]) ? params[:direction] : "asc"
  end
end

helpers/application_helpers.rb

module ApplicationHelper
    def sortable(column, title = nil)
    title ||= column.titleize
    css_class = column == sort_column ? "current #{sort_direction}" : nil
    direction = column == sort_column && sort_direction == "asc" ? "desc" : "asc"
    link_to title, params.merge(:sort => column, :direction => direction, :page => nil), {:class => css_class}
  end
end

Please check the codes and try to resolve this soon.