ruby on rails - No Route error when passing parameters through link_to -

error:

no route matches {:action=>"new", :controller=>"comments", :parent_id=>1}

routes.rb:

myapp::application.routes.draw   resources :posts     resources :comments   end   resources :topics     resources :posts   end   root :to => "posts#index" end 

models:

class topic < activerecord::base   has_many        :posts, :dependent => :destroy   attr_accessible :name, :post_id end  class post < activerecord::base   belongs_to :topic,    :touch => true   has_many   :comments, :dependent => :destroy   accepts_nested_attributes_for :topic   attr_accessible :name, :title, :content, :topic, :topic_attributes end  class comment < activerecord::base   has_ancestry   attr_accessible :name, :content   belongs_to      :post, :touch => true end 

view:

<%= link_to "reply", new_post_comment_path(@post, :parent_id => comment.id) %>  

controller:

class commentscontroller < applicationcontroller   respond_to :html, :xml   def show     @post = post.find(params[:id])     @comments = @post.comments.order("updated_at").page(params[:page])   end    def create     @post = post.find(params[:post_id])     @comment = @post.comments.build(params[:comment])     if @comment.save       flash[:notice] = "replied \"#{@post.title}\""       redirect_to(@post)     else       flash[:notice] = "reply failed save."       redirect_to(@post)     end   end    def new     @post = post.find(params[:post_id])     @comment = comment.new(:parent_id => params[:parent_id])      # @comment = @post.comments.build   end    def destroy     @post = post.find(params[:post_id])     @comment = @post.comments.find(params[:id])     @comment.destroy     redirect_to post_path(@post)   end end 

by reading code might have gathered trying ancestry gem work nested resources. i've been using railscasts episode on ancestry gem guide me. reading question.

try pass comment id

link_to "reply", new_post_comment_path(@post, :parent_id => comment.id).