Question

When I try to go to this url: http://localhost:3000/lessons/18/pages, I get this error:

No route matches {:action=>"show", :controller=>"pages", :lesson_id=>#<Page id: 5,
title: "Page One", page_num: 1, lesson_id: 18, stats_id: nil, sources_id: nil,
created_at: "2012-04-06 04:55:39", updated_at: "2012-04-06 04:55:39">}

I have two tables: lessons, pages

page.rb

belongs_to :lessons

lessons.rb

has_many :pages

routes.rb

resources :lessons do
   resources :pages
end

The pages index looks like this:

<% @lesson.pages.each do |page| %>
 <tr>
  <td><%= page.title %></td>
  <td><%= page.page_num %></td>
  <td><%= page.lesson_id %></td>
  <td><%= page.stats_id %></td>
  <td><%= page.sources_id %></td>
  <td><%= link_to 'Show', lesson_page_path(page) %></td>
  <td><%= link_to 'Edit', edit_page_path(page) %></td>
  <td><%= link_to 'Destroy', lesson_page, confirm: 'Are you sure?', method: :delete %></td>
 </tr>
<% end %>

And here is the pages controller:

def index
 @lesson = Lesson.find(params[:lesson_id])
    respond_to do |format|
    format.html # index.html.erb
    format.json { render json: @pages }
  end
end

Why is the show route not working?

Answer 1

With nested resource routes you need to pass all the objects in the route:

lesson_page_path(@lesson, page)

The error is somewhat revealing of this in that it shows that it’s trying to get the :lesson_id from a Page instance.