Rails Getting Started Question

Question

I'm a newbie in rails, and I've been looking all over for an answer for this issue. Here's what I have:

class Item < ActiveRecord::Base belongs_to :book class Book < ActiveRecord::Base has_many :items

Now I want to list all the items with their properties and the book associated with them. They would go under index in the items_controller.rb

class ItemsController < ApplicationController # GET /items # GET /items.xml def index @items = Item.all

now how would I handle books in the ItemsController so I can list them in index.html.erb keeping in mind that an item belongs to only one book? if I add:

@books = items.book.find

right under @items = Item.all so I can reference them in the index.html.erb I get:

undefined method 'book' for #<Array:0x10427f998>

I have a feeling that the answer is so simple but so far I haven't figured it out. Is there any tutorial that you guys are aware of that covers this matter?

Thank you!

Ryan McGeary · Accepted Answer · 2009-12-24 15:35:35Z

In your view, when you iterate over all of your @items, just reference the book for each one. Example ERB (app/views/items/index.html.erb):

<% @items.each do |item| -%> Item: <%= item.name %> Book: <%= item.book.title %> <% end -%>

If instead your intention is to display each book with the associated items under each book, you'd be better off using the index action on the BooksController. Find all the books, iterate over each book, and for each book, iterate over the items for that book.

Thank you for the answer. I also had some bad data that cause some of the problems, but this totally works. Thank you!

Brian Kelly · Accepted Answer · 2009-12-24 15:24:29Z

The array of items doesn't have a book, each individual item does. It looks like you're trying to get the book of ALL the items, which doesn't exist.

Try @items[0].book or using a loop in your view:

<ul> <% for item in @items %> <li><%= item.book.title %></li> <% end %> </ul>

You could also use a partial to iterate through the array. See the section "Rendering a collection of partials" at http://api.rubyonrails.org/classes/ActionView/Partials.html

Kaleb Brasee · Accepted Answer · 2009-12-24 15:26:54Z

The problem is that you're calling items.book on an array of items, and the array doesn't have a method named book (hence the error). You'd need to get a single book from that array (such as items[0]), then call .book on that.

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