I am going over some basic guides in Rails, reviewing the basics and such for an upcoming exam. One of the guides included was the sort-of-standard getting started guide over at guide.rubyonrails.org. Here is the link if you need it. Also all my code is for my app is from there, so I have no problem releasing any of my code since it should be the same as shown there. I didn't do a copy paste, but I basically was typing with Vim in one half of my screen and the web page in the other half, typing what I see.

http://guides.rubyonrails.org/getting_started.html

So like I said, I am going along the guide when I noticed past a certain point in the tutorial, I was always getting an error on the site. To find the section of code, just hit Ctrl+f on the page (or whatever you have search/find set to) and enter "accepts_". This should immediately direct you to this chunk of code.

class Post < ActiveRecord::Base
  validates_presence_of :na开发者_Go百科me, :title
  validates_length_of :title, :minimum => 5
  has_many :comments
  has_many :tags

  accepts_nested_attributes_for :tags, :allow_destroy => :true  ,
   :reject_if => proc { |attrs| attrs.all? { |k, v| v.blank? } }
end

So I tried putting this in my code. It is in ~/Rails/blog/app/models/post.rb in case you are wondering. However, even after all the other code I put in past that in the guide, hoping I was just missing some line of code that would come up later in the guide. But nothing, same error every time. This is what I get.

---

NoMethodError in PostsController#index

undefined method `accepts_nested_attributes_for' for #<Class:0xb7109f98>

/usr/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/base.rb:1833:in `method_missing' app/models/post.rb:7 app/controllers/posts_controller.rb:9:in `index'

Request

Parameters:

None

Response

Headers:

{"Content-Type"=>"", "cookie"=>[], "Cache-Control"=>"no-cache"}

---

Now, I copied the above code from the guide. The two code sections I edited mentioned in the error message I will paste as is below.

---

class PostsController < ApplicationController
  # GET /posts
  # GET /posts.xml

  before_filter :find_post,
    :only => [:show, :edit, :update, :destroy]

  def index
    @posts = Post.find(:all) # <= the line 9 referred to in error message

    respond_to do |format|
      format.html # index.html.erb
      format.xml  { render :xml => @posts }
    end
  end

---

class Post < ActiveRecord::Base
  validates_presence_of :name, :title
  validates_length_of :title, :minimum => 5
  has_many :comments
  has_many :tags

  accepts_nested_attributes_for :tags, :allow_destroy => :true  , # <= problem
    :reject_if => proc { |attrs| attrs.all? { |k, v| v.blank? } }
end

---

Also here is gem local gem list. I do note that they are a bit out of date, but the default Rails install any of the school machines (an environment likely for my exam) is basically 'gem install rails --version 2.2.2' and since they are windows machines, they come with all the normal windows ruby gems that comes with the ruby installer. However, I am running this off a Debian virtual machine of mine, but trying to set it up similarly and I figured the windows ruby gems wouldn't change anything in Rails.

*** LOCAL GEMS ***

actionmailer (2.2.2)
actionpack (2.2.2)
activerecord (2.2.2)
activeresource (2.2.2)
activesupport (2.2.2)
gem_plugin (0.2.3)
hpricot (0.8.2)
linecache (0.43)
log4r (1.1.7)
ptools (1.1.9)
rack (1.1.0)
rails (2.2.2)
rake (0.8.7)
sqlite3-ruby (1.2.3)

---

If you look on http://apidock.com/rails/ActiveRecord/NestedAttributes/ClassMethods/accepts_nested_attributes_for you'll see that accepts_nested_attributes_for only exists since Rails 2.3.2, so I'm afraid you won't have that functionality if you're running off of 2.2.

---

You must upgrade to 2.3.2 or higher as Antonio suggests. I suggest using 2.3.5. You can either upgrade the gems on the system or freeze Rails to your application.

To upgrade the gems

gem install rails -v=2.3.5

To freeze Rails

cd /your/app/
git clone git://github.com/rails/rails vendor/rails
cd vendor/rails
git checkout v2.3.5