是否有任何教程如何搭建使用多对多关系的简单模型？

最佳答案

我在 Rails 3.0.5 上使用 ruby​​ 1.9.2 一步一步创建下面的 testapp 时写的。另请参阅我使用的 gem 的“Gemfile”(整个 Testapp 可下载，链接位于第 15 部分的末尾)。所以这里是:

1) 去一个你想创建一个测试应用程序的地方，然后

rails new mynewtestapp
cd mynewtestapp

rails g scaffold book title:string author:string
rails g scaffold user name:string age:integer

rails g migration createBooksUsers

class CreateBooksUsers < ActiveRecord::Migration
  def self.up
  end

  def self.down
  end
end

class CreateBooksUsers < ActiveRecord::Migration
  def self.up
    create_table :books_users, :id => false do |t|
      t.integer :book_id
      t.integer :user_id
    end
  end

  def self.down
    drop_table :books_users
  end
end

class Book < ActiveRecord::Base
  attr_accessible :title, :author, :user_ids
  has_and_belongs_to_many :users
end

class User < ActiveRecord::Base
  attr_accessible: :name, :age, :book_ids
  has_and_belongs_to_many :books
end

rake db:create
rake db:migrate

echo "gem 'simple_form', :git => 'git://github.com/plataformatec/simple_form.git'" >> Gemfile

bundle install

rails g simple_form:install

01    <%= form_for(@book) do |f| %>
02      <% if @book.errors.any? %>
03        <div id="error_explanation">
04          <h2><%= pluralize(@book.errors.count, "error") %> prohibited this book from being saved:</h2>
05    
06          <ul>
07          <% @book.errors.full_messages.each do |msg| %>
08            <li><%= msg %></li>
09          <% end %>
10          </ul>
11        </div>
12      <% end %>
13    
14      <div class="field">
15        <%= f.label :title %><br />
16        <%= f.text_field :title %>
17      </div>
18      <div class="field">
19        <%= f.label :author %><br />
20        <%= f.text_field :author %>
21      </div>
22      <div class="actions">
23        <%= f.submit %>
24      </div>
25    <% end %>

01    <%= simple_form_for(@book) do |f| %>
02      <% if @book.errors.any? %>
03        <div id="error_explanation">
04          <h2><%= pluralize(@book.errors.count, "error") %> prohibited this book from being saved:</h2>
05    
06          <ul>
07          <% @book.errors.full_messages.each do |msg| %>
08            <li><%= msg %></li>
09          <% end %>
10          </ul>
11        </div>
12      <% end %>
13    
14      <%= f.input :title %>
15      <%= f.input :author %>
16      <%= f.association :users %>
17    
18      <%= f.button :submit %>
19    
20    <% end %>

rails s

public/stylesheets/simple_form.css

/* public/stylesheets/simple_form.css */
.simple_form label {
  float: left;
  width: 100px;
  text-align: right;
  margin: 2px 10px;
}

.simple_form div.input {
  margin-bottom: 10px;
}

.simple_form div.boolean, .simple_form input[type='submit'] {
  margin-left: 120px;
}

.simple_form div.boolean label, .simple_form label.collection_radio, .simple_form label.collection_check_boxes{
  float: none;
  margin: 0;
}

.simple_form .error {
  clear: left;
  margin-left: 120px;
  font-size: 12px;
  color: #D00;
  display: block;
}

.simple_form .hint {
  clear: left;
  margin-left: 120px;
  font-size: 12px;
  color: #555;
  display: block;
  font-style: italic;
}

15      <%= f.input :author %>

15      <%= f.input :author, :as => :check_boxes %>

  # You can wrap a collection of radio/check boxes in a pre-defined tag, defaulting to none.
  config.collection_wrapper_tag = :fieldset

  # You can wrap each item in a collection of radio/check boxes with a tag, defaulting to none.
  config.item_wrapper_tag = :div

fieldset { border: 0; }

class User < ActiveRecord::Base
  has_and_belongs_to_many :users

  def to_label
    "#{name} (#{age})"
  end

end

01    <p id="notice"><%= notice %></p>
02    
03    <p>
04      <b>Title:</b>
05      <%= @book.title %>
06    </p>
07    
08    <p>
09      <b>Author:</b>
10      <%= @book.author %>
11    </p>
12    
13    <p>
14      <b>Who owns a copy?</b>
15      <%= @book.users.map {|x| x.to_label}.join ', ' %>
16    </p>
17    
18    <%= link_to 'Edit', edit_book_path(@book) %> |
19    <%= link_to 'Back', books_path %>

关于mysql - rails 3 关系模型的脚手架，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/5384203/