UrlgenerationErrorを直したい

Question

###前提・実現したいこと
rails gem 'ancestry'を使ってcommentに対してreplyを行いたいと思い、
以下の設定で行っていたのですが、ActionController::UrlGenerationError in Messages#showでつまづいてしまいました。どのようにしたらよろしいでしょうか？
###発生している問題・エラーメッセージ

エラーメッセージ
ActionController::UrlGenerationError in Messages#show
No route matches {:action=>"new", :controller=>"comments", :id=>"1", :parent_id=>#<Comment id: 1, content: "test", message_id: 1, user_id: 1, created_at: "2017-04-23 04:20:30", updated_at: "2017-04-23 04:20:30", ancestry: nil>} missing required keys: [:message_id]

p>Posted: <%= link_to comment.user.username, user_path(user) %><%= image_tag (user.avatar.url(:thumb)) unless user.avatar.blank?  %> <%= comment.created_at.strftime("%Y/%m/%d %H:%M") %> <%= link_to "Reply", new_message_comment_path(:parent_id => comment) %></p>

Request

Parameters:

{"id"=>"1"}

###該当のソースコード

class AddAncestryToComments < ActiveRecord::Migration[5.0]
  def change
    add_column :comments, :ancestry, :string
    add_index :comments, :ancestry
  end

  def self.down
    remove_column :comments, :ancestry
    remove_index :comments, :ancestry
  end
end

comment.rb

class Comment < ApplicationRecord
  belongs_to :message
  belongs_to :user
  has_ancestry
end

messages/show

<%= link_to "Reply", new_message_comment_path(:parent_id => comment) %>

comments_controller

class CommentsController < ApplicationController
  before_action :find_message, only: [:create, :edit, :update, :destroy]
  before_action :find_comment, only: [:edit, :update, :destroy]
  before_action :authenticate_user!

  def new
    @comment = Comment.new(:parent_id => params[:parent_id])
  end

  def create
    @comment = @message.comments.create(comment_params)
    @comment.user_id = current_user.id

    if @comment.save
      redirect_to message_path(@message)
    else
      render 'new'    
    end
  end

  def edit
  end

  def update
    if @comment.update(comment_params)
      redirect_to message_path(@message)
    else
      render 'edit'    
    end  
  end

  def destroy
    @comment.destroy
    redirect_to message_path(@message)
  end


private

   def comment_params
     params.require(:comment).permit(:content, :parent_id)
   end

   def find_message
     @message = Message.find(params[:message_id])
   end

   def find_comment
     @comment = @message.comments.find(params[:id])
   end
end

comment routes

message_comments POST   /messages/:message_id/comments(.:format)          comments#create
     new_message_comment GET    /messages/:message_id/comments/new(.:format)      comments#new
    edit_message_comment GET    /messages/:message_id/comments/:id/edit(.:format) comments#edit
         message_comment PATCH  /messages/:message_id/comments/:id(.:format)      comments#update
                         PUT    /messages/:message_id/comments/:id(.:format)      comments#update
                         DELETE /messages/:message_id/comments/:id(.:format)      comments#destroy

routes.rb

resources :messages do
    member do
      post "add", to: "favorites#create"
      get "show_favorites" => "favorites#show_favorites"
    end
    resources :comments, only: [:create, :edit, :update, :destroy, :new]
  end

###試したこと
UrlGenerationErrorとなってたので、routesでget '/comments/new/(:parent_id)', to: 'comments#new'を設定してみたのですがダメでした。

###補足情報(言語/FW/ツール等のバージョンなど)
より詳細な情報
ruby on rails, cloud9

Answer 1

 <%= link_to "Reply", new_message_comment_path(comment.message, :parent_id => comment.id) %>

とすることによって、エラーをなくすことができました。