Rails 3 has_many通过3个表 [英] Rails 3 has_many through with 3 tables

问题描述

我用这个Bang了我的头，我问过类似的东西，但是没有任何地方。所以我有三个表超级英雄，权力和团队。一个超级英雄可以拥有许多权力和许多团队，一个权力可以与许多超级英雄相关联，一个团队由许多超级英雄组成。我决定把这些保存到一个大的关系表（我称之为Marvel）。

这是我设置的：

  class Superhero< ActiveRecord :: Base 
 attr_accessible：name，：power_ids，：team_ids，：attributes_marvels 
 
 has_many：marvels，：dependent => ：destroy 
 has_many：powers，：through => ：marvels 
 has_many：teams，：through => ：marvels 
 acceptance_nested_attributes_for：marvels 
 end 
 
 class Power< ActiveRecord :: Base 
 attr_accessible：name 
 
 has_many：marvels，：dependent => ：destroy 
 end 
 
 class Team< ActiveRecord :: Base 
 attr_accessible：name 
 
 has_many：marvels，：dependent => ：destroy 
 end 
 
 class Marvel< ActiveRecord :: Base 
 attr_accessible：power_id，：superhero_id，：team_id 
 
 belongs_to：superhero 
 belongs_to：power 
 belongs_to：team 
 end 
  

以下是创建超级英雄的表单：

 <％= form_for（@superhero）do | f | ％> 
< div class =field> 
<％= f.label：name％>< br /> 
<％= f.text_field：name％> 
< / div> 
< div class =field> 
< p>请选择您的工作组：< / p> 
<％= f.collection_select（：team_ids，Team.all（：order =>：name），：id，：name，{：prompt => true}）％> 
< / div> 
< div class =field> 
< p>请检查适用于您的所有权力。< / p> 
<％Power.all.each do | power | ％> 
< label class =checkbox> 
<％= check_box_tagsuperhero [power_ids] []，power.id，@ superhero.power_ids.include？（power.id）％> 
<％= power.name％> 
< / label> 
<％end％> 
< / div> 
< div class =actions> 
<％= f.submit％> 
< / div> 
<％end％> 
  

超级英雄控制器

  def new 
 @superhero = Superhero.new 
 end 
 
 def create 
 @superhero = Superhero.new（params [：superhero]） 
 end 
  

我已经创建了这样的方式，因为我想要能够在一个表单请问，（复选框）权力列表（下拉列表）一个团队列表，现在显示了一个基于这些条件的超级英雄列表。

我有这个几乎工作但存在问题，我注意到在记录器文件它给我这样的：

 参数：{utf8 = power_ids=> [1]}，commit=>创建超级英雄} 
 
 INSERT INTOsuperheros（created_at，name，updated_at VALUES（？，？，？）[[created_at，Thu，2013年2月7日19:59:24 UTC +00：00]，[name，Storm]，[updated_at，Thu，07 Feb 201319:59:24 UTC +00：00]] 
 
 INSERT INTOmarvels（created_at，power_id，superhero_id，team_id，updated_at）VALUES ，[...]，[...] [0 [[created_at，Thu，07 Feb 2013 19:59:24 UTC +00：00]，[power_id，nil]，[superhero_id，8] [team_id，3]，[updated_at，Thu，2013年2月7日19:59:24 UTC +00：00]] 
 
 INSERT INTOmarvels（created_at，power_id ，superhero_id，team_id，updated_at）VALUES（？，？，？，？，？）[[created_at，Thu，07 Feb 2013 19:59:24 UTC +00：00] power_id，1]，[superhero_id，8]，[team_id，nil]，[updated_at，Thu，07 Feb 2013 19:59:24 UTC +00：00]] 
  

为什么会插入两次，为什么会显示参数中的值？

解决方案

您需要在表的两边创建依赖：

  class Superhero< ActiveRecord :: Base 
 attr_accessible：name，：power_ids，：team_ids，：attributes_marvels 
 
 has_many：marvels，：dependent => ：destroy 
 has_many：powers，：through => ：marvels 
 has_many：teams，：through => ：marvels 
 acceptance_nested_attributes_for：marvels 
 end 
 
 class Power< ActiveRecord :: Base 
 attr_accessible：name 
 
`has_many：superheros，：through => ：marvels` 
 has_many：marvels，：dependent => ：destroy 
 end 
 
 class Team< ActiveRecord :: Base 
 attr_accessible：name 
 
`has_many：superheros，：through => ：marvels` 
 has_many：marvels，：dependent => ：destroy 
 end 
 
 class Marvel< ActiveRecord :: Base 
 attr_accessible：power_id，：superhero_id，：team_id 
 
 belongs_to：superhero 
 belongs_to：power 
 belongs_to：team 
 end 
  

这样你就可以在Marvels中为每个模型添加ID密钥，并且能够访问它们，并在assosiations指导

Banging my head with this one, I've asked something similar, but getting nowhere with it. So I have three tables Superheros, Powers, and Teams. A superhero can have many powers and many teams, a power can relate to many superheros, and a team consists of many superheros. I've decided to save these to a big relationship table (which I call Marvel)

Here's what I have set up:

class Superhero < ActiveRecord::Base
  attr_accessible :name, :power_ids, :team_ids, :attributes_marvels

  has_many :marvels, :dependent => :destroy
  has_many :powers, :through => :marvels
  has_many :teams, :through => :marvels
  accepts_nested_attributes_for :marvels
end

class Power < ActiveRecord::Base
  attr_accessible :name

  has_many :marvels, :dependent => :destroy
end

class Team < ActiveRecord::Base
  attr_accessible :name

  has_many :marvels, :dependent => :destroy
end

class Marvel < ActiveRecord::Base
  attr_accessible :power_id, :superhero_id, :team_id

  belongs_to :superhero
  belongs_to :power
  belongs_to :team
end

Here's the form to create the superhero:

<%= form_for(@superhero) do |f| %>
 <div class="field">
  <%= f.label :name %><br />
  <%= f.text_field :name %>
 </div>
<div class="field">
 <p>Please select which team you work for:</p>
 <%= f.collection_select(:team_ids, Team.all(:order=>:name), :id, :name, {:prompt => true}) %>
 </div>
 <div class="field">
<p>Please check all powers that apply to you.</p>
<% Power.all.each do |power| %>
     <label class="checkbox">
     <%= check_box_tag "superhero[power_ids][]", power.id, @superhero.power_ids.include?(power.id) %>
     <%= power.name %>
    </label>
    <% end %>
 </div>
 <div class="actions">
  <%= f.submit %>
 </div>
<% end %>

Controller for superhero

  def new
   @superhero = Superhero.new
  end

  def create
   @superhero = Superhero.new(params[:superhero])
  end

I've created this way because I want to be able to in a form ask, (checkboxes)A list of powers, (dropdown)A list of teams, now show me a list of superheros based on those criteria.

I've got this almost working but having problems with the save, I noticed in the logger file it's giving me this:

Parameters: {"utf8"=>"✓", "authenticity_token"=>"sgD0NIjDM8QhMdzSsb7M/+PFd+FxMtNeOGukrdw9qFA=", "superhero"=>{"name"=>"Storm", "team_ids"=>"3", "power_ids"=>["1"]}, "commit"=>"Create Superhero"}

INSERT INTO "superheros" ("created_at", "name", "updated_at") VALUES (?, ?, ?)  [["created_at", Thu, 07 Feb 2013 19:59:24 UTC +00:00], ["name", "Storm"], ["updated_at", Thu, 07 Feb 2013 19:59:24 UTC +00:00]]

INSERT INTO "marvels" ("created_at", "power_id", "superhero_id", "team_id", "updated_at") VALUES (?, ?, ?, ?, ?)[0m  [["created_at", Thu, 07 Feb 2013 19:59:24 UTC +00:00], ["power_id", nil], ["superhero_id", 8], ["team_id", 3], ["updated_at", Thu, 07 Feb 2013 19:59:24 UTC +00:00]]

INSERT INTO "marvels" ("created_at", "power_id", "superhero_id", "team_id", "updated_at") VALUES (?, ?, ?, ?, ?)  [["created_at", Thu, 07 Feb 2013 19:59:24 UTC +00:00], ["power_id", 1], ["superhero_id", 8], ["team_id", nil], ["updated_at", Thu, 07 Feb 2013 19:59:24 UTC +00:00]]

why is it inserting twice and why are there Nil values when you can plainly see the values in the parameters?

解决方案

You need to create dependancies in both sides of the tables:

class Superhero < ActiveRecord::Base
  attr_accessible :name, :power_ids, :team_ids, :attributes_marvels

  has_many :marvels, :dependent => :destroy
  has_many :powers, :through => :marvels
  has_many :teams, :through => :marvels
  accepts_nested_attributes_for :marvels
end

class Power < ActiveRecord::Base
  attr_accessible :name

  `has_many :superheros, :through => :marvels`
  has_many :marvels, :dependent => :destroy
end

class Team < ActiveRecord::Base
  attr_accessible :name

  `has_many :superheros, :through => :marvels`
  has_many :marvels, :dependent => :destroy
end

class Marvel < ActiveRecord::Base
  attr_accessible :power_id, :superhero_id, :team_id

  belongs_to :superhero
  belongs_to :power
  belongs_to :team
end

this way you add ID keys in Marvels for each model and ull be able to acces them all, check it at assosiations guide

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