许多一对多连接和协会 [英] Many-to-many connection and Associations

问题描述

一个用户可以上传通过剪辑脚手架剪辑，这个片段无论是属于显示键，或专辑（显示控制器，专辑控制器）。

A User can Upload a Clip via the Clips Scaffold, this clip either belongs to a Show and or an Album (Show Controller, Album Controller).

一个用户可以有

• ONLY ONE SHOW



• 多张唱片

• ONLY ONE SHOW

• MANY ALBUMS

我试图做到：

A 用户可以上传剪辑后，这些片段可以连接到任何一个显示或/和专辑

A User can Upload Clips, these clips can be attached to either a Show or/and an Album

有关更详细的介绍一起来看看下面的图片：

For a more detailed overview take a look at the image below:

问题1 什么我不理解是我必须使用关联。我目前的型号：

Problem #1 What i'm not understanding is the associations i must use. My current Models:

的用户模型的：

has_many :clips, dependent: :destroy
has_one :show, dependent: :destroy
has_many :albums, dependent :destroy

的夹型号的 belongs_to的：用户

的显示模式的 belongs_to的：用户

的相册样板的 belongs_to的：用户

---------------------------------------------------------------------------------

问题＃2 我不知道如何来完成的，当用户上传的剪辑，他可以附加（或指定）到一个显示或专辑。

Problem #2 I'm not sure on how to accomplish, that when a user uploads a Clip, he can attach (or assign) it to a Show or Album.

我做了与显示（因为只有一个）只是调用＆LT;％= @ user.clip％>在View页面。

What i did with the Show (because there is only one) was just to call <%= @user.clip %> on the View Page.

这意味着，每个剪辑出用户上传的出现在显示。

这是错误的...

现在我有一个显示和专辑我要隆重用户的能力，以选择在哪里安装（在一在众多专辑他都有，或者他展）。

Now that i have a Show AND an Album i must grand the user the ability to choose where to attach it (On one of the many albums he have, or his Show).

或者我应该有一个解决方案，去那里的用户可以上传剪辑通过的相册或显示控制器（不通过单独的剪辑控制器）

Or should i go with a solution where the User can Upload a Clip THROUGH the Albums or Show controller (not through the separate Clips Controller)

我真的可以在这里需要一些帮助：）

推荐答案

您的问题＃1是多态协会的​​教科书案例。

Your problem #1 is a textbook case of polymorphic association.

class User < ActiveRecord::Base
  has_one         :show,
                  :dependent => :destroy
  has_many        :clips,
                  :dependent => :destroy
  has_many        :albums,
                  :dependent => :destroy
end

class Clip < ActiveRecord::Base
  belongs_to      :user
  belongs_to      :attachable,
                  :polymorphic => true
end

class Show < ActiveRecord::Base
  belongs_to      :user
  has_many        :clips,
                  :as => :attachable
end

class Album < ActiveRecord::Base
  belongs_to      :user
  has_many        :clips,
                  :as => :attachable
end

您可以在的Rails指南了解更多关于多态关联。

You can learn more about polymorphic associations at Rails Guides.

现在您的问题＃2，假设你做你的迁移按照你上面链接的引导必须在你的剪辑两台数据库领域表：

Now for your problem #2, assuming you do your migrations as per the guide linked above you'll have two database fields in your clips table:

• attachable_id - 这是 ID 显示的实例或专辑那将收到的关联。


• attachable_type - 这是目标对象的类名，这样无论是显示或专辑。

• attachable_id - This is the id of the instance of Show or Album that's going to receive the association.
• attachable_type - This is the class name of the target object, so either Show or Album.

在你上传表单，你要表现出节目和/或专辑的列表，并在 ID 分配给 attachable_id 和类名 attachable_type 。

In your upload form, you're going to show a list of shows and/or albums and assign the id to attachable_id and the class name to attachable_type.

我会建议加载了你最初的选择只有一个类，然后通过JavaScript的情况下，替换它的内容，用户选择第二个选项。像这样：

I would suggest loading up your initial select with only one class and then replacing its contents via JavaScript in case the user selects the second option. Like so:

<%= f.collection_select :attachable_type, [['Show'], ['Album']], :first, :first, { :selected => 'Show' }, { :include_blank => false } %>
<%= f.collection_select :attachable_id, Show.all, :id, :name %>

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