如何构建由多个模型的Rails的JSON响应 [英] How to build a JSON response made up of multiple models in Rails

问题描述

首先，将所需的结果

我有用户和项目模型。我想建立一个JSON响应，看起来像这样：

  {
  用户：
    {用户名：鲍勃，富：无论，酒吧：你好！}，

  项目：
    {ID：1，名：一，ZIM：行星，吉尔：土}，
    {ID：2，名：二，ZIM：行星，吉尔：火星}
  ]
}
 

不过，我的用户和项目模式比只是那些更多的属性。我找到了一种方法来得到这个工作，但提防，它不是pretty的...请帮助...

更新

接下来的部分包含了原来的问题。最后一节显示了新的解决方案。

---

我的黑客

home_controller.rb

 类的HomeController＆LT;的ApplicationController

  DEF观察
    respond_to代码做|格式|
      format.js {渲染：JSON =＆GT; Observation.new（CURRENT_USER，@items）.to_json}
    结束
  结束

结束
 

observation.rb

 ＃注：这是不是的ActiveRecord的子类::基地
＃这个类只是充当一个容器聚合所有可观察的对象
课堂观察
  attr_accessor：用户：项目

  高清初始化（用户资料）
    self.user =用户
    self.items =项目
  结束

  ＃的JSON必须是在它之前发送到`to_json`方法在home_controller否则JSON将被转义德codeD ...
  ＃ 真是一团糟！
  高清to_json
    {
      ：用户=＆GT;的ActiveSupport :: JSON.de code（user.to_json（：只=＆GT;：用户名：方法=＆GT; [：foo，那么：巴]）），
      ：项目=＆GT;的ActiveSupport :: JSON.de code（auctions.to_json（：只=＆GT; [：ID，：姓名]：方法=＆GT; [：ZIM，：GIR]））
    }
  结束
结束
 

---

看马！没有更多的黑客！

覆盖 as_json 而不是

的<一个href="http://api.rubyonrails.org/classes/ActiveRecord/Serialization.html#M001874">ActiveRecord::Serialization#as_json文档是pretty的稀疏。下面是简单的：

  as_json（选项=无）
  [节目源]
 

有关 to_json VS as_json 的详细信息，请参阅的Overriding to_json 2.3.5

的code SANS黑客

user.rb

 类用户的LT;的ActiveRecord :: Base的

  高清as_json（选项）
    选项​​= {：只=＆GT; [：用户名]：方法=＆GT; [：foo，那么：巴]} .merge（选项）
    超（选项）
  结束

结束
 

item.rb的

 类项目＆lt;的ActiveRecord :: Base的

  高清as_json（选项）
    选项​​= {：只=＆GT; [：ID，名称]：方法=＆GT; [：ZIM，：GIR]} .merge（选项）
    超（选项）
  结束

结束
 

home_controller.rb

 类的HomeController＆LT;的ApplicationController

  DEF观察
    @items = Items.find（...）
    respond_to代码做|格式|
      format.js做
        渲染：JSON =＆GT; {
          ：用户=＆GT; CURRENT_USER || {}，
          ：项目=＆GT; @items
        }
      结束
    结束
  结束

结束
 

解决方案

EDITED 使用 as_json 而不是 to_json 。请参阅<一href="http://stackoverflow.com/questions/2572284/override-to-json-in-rails-2-3-5/2574900">http://stackoverflow.com/questions/2572284/override-to-json-in-rails-2-3-5/2574900对于详细的解释。我觉得这是最好的答案。

可以呈现在控制器所需的JSON，而不需要辅助模型

 高清观察
  respond_to代码做|格式|
    format.js做
      渲染：JSON =＆GT; {
        ：用户=＆GT; current_user.as_json（：只=＆GT; [：用户名]：方法=＆GT; [：foo，那么：巴]），
        ：项目=＆GT; @ items.collect {| I | i.as_json（：只=＆GT; [：ID，：姓名]：方法=＆GT; [：ZIM，：GIR]）}
      }
    结束
  结束
结束
 

确认的ActiveRecord :: Base.include_root_in_json 设置为false，否则你会得到一个'用户'属性'用户'的内部。不幸的是，它看起来像阵列不通过选项到每一个元素，因此收集是必要的。

First, the desired result

I have User and Item models. I'd like to build a JSON response that looks like this:

{
  "user":
    {"username":"Bob!","foo":"whatever","bar":"hello!"},

  "items": [
    {"id":1, "name":"one", "zim":"planet", "gir":"earth"},
    {"id":2, "name":"two", "zim":"planet", "gir":"mars"}
  ]
}

However, my User and Item model have more attributes than just those. I found a way to get this to work, but beware, it's not pretty... Please help...

Update

The next section contains the original question. The last section shows the new solution.

---

My hacks

home_controller.rb

class HomeController < ApplicationController

  def observe
    respond_to do |format|
      format.js { render :json => Observation.new(current_user, @items).to_json }
    end
  end

end

observation.rb

# NOTE: this is not a subclass of ActiveRecord::Base
# this class just serves as a container to aggregate all "observable" objects
class Observation
  attr_accessor :user, :items

  def initialize(user, items)
    self.user = user
    self.items = items
  end

  # The JSON needs to be decoded before it's sent to the `to_json` method in the home_controller otherwise the JSON will be escaped...
  # What a mess!
  def to_json
    {
      :user => ActiveSupport::JSON.decode(user.to_json(:only => :username, :methods => [:foo, :bar])),
      :items => ActiveSupport::JSON.decode(auctions.to_json(:only => [:id, :name], :methods => [:zim, :gir]))
    }
  end
end

---

Look Ma! No more hacks!

Override as_json instead

The ActiveRecord::Serialization#as_json docs are pretty sparse. Here's the brief:

as_json(options = nil) 
  [show source]

For more information on to_json vs as_json, see the accepted answer for Overriding to_json in Rails 2.3.5

The code sans hacks

user.rb

class User < ActiveRecord::Base

  def as_json(options)
    options = { :only => [:username], :methods => [:foo, :bar] }.merge(options)
    super(options)
  end

end

item.rb

class Item < ActiveRecord::Base

  def as_json(options)
    options = { :only => [:id, name], :methods => [:zim, :gir] }.merge(options)
    super(options)
  end

end

home_controller.rb

class HomeController < ApplicationController

  def observe
    @items = Items.find(...)
    respond_to do |format|
      format.js do
        render :json => {
          :user => current_user || {},
          :items => @items
        }
      end
    end
  end

end

解决方案

EDITED to use as_json instead of to_json. See http://stackoverflow.com/questions/2572284/override-to-json-in-rails-2-3-5/2574900 for a detailed explanation. I think this is the best answer.

You can render the JSON you want in the controller without the need for the helper model.

def observe
  respond_to do |format|
    format.js do
      render :json => {
        :user => current_user.as_json(:only => [:username], :methods => [:foo, :bar]),
        :items => @items.collect{ |i| i.as_json(:only => [:id, :name], :methods => [:zim, :gir]) }
      }
    end
  end
end

Make sure ActiveRecord::Base.include_root_in_json is set to false or else you'll get a 'user' attribute inside of 'user'. Unfortunately, it looks like Arrays do not pass options down to each element, so the collect is necessary.

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