指定一个Rails的属性对象传递到一个JSON对象 [英] Specifying attributes of a Rails object passed into a JSON object

问题描述

我在Rails的一个对象具有属性A，B，C，D和E.当通过这个对象返回给客户端通过JSON对象，我怎么能告诉导轨控制器只包含一个属性并在JSON对象D'

在我的用户控制器，我的code是如下：

  @user = User.find（PARAMS [：ID]）    做的respond_to |格式|
        format.html
        format.json {渲染：JSON =＆GT; @用户}
    结束
 

这code工作，然而，返回的JSON对象包含@user对象的所有属性。我怎么能限制包括在JSON对象的属性之前发送任何内容返回给客户端？

更新：lucapette提供有关发生了什么幕后的一些良好的背景。因为有次我可能希望返回所有属性的时候，我结束了使用以下code：

  format.json {渲染：JSON =＆GT; @ user.to_json（：只=＆GT;身份证]）}
 

解决方案

 渲染：JSON =＆GT; @用户
 

将调用 to_json 的@user对象。和 to_json 方法将使用 as_json 的方法做其工作。所以，你可以很容易地覆盖 as_json 来只有你想要给客户什么通过。就像下面这个：

 高清as_json选项= {}
  {
    ATTR1：ATTR1，
    attR2位：attR2位
  }
结束
 

I have an object in Rails that has attributes A, B, C, D, and E. When passing this object back to the client-side through a JSON object, how can I tell the rails controller to only include attributes A and D in the JSON object?

Within my Users controller, my code is as follows:

    @user = User.find(params[:id])

    respond_to do |format|
        format.html
        format.json { render :json => @user}
    end

This code works, however, the JSON object that is returned contains all the attributes of the @user object. How can I limit the attributes that are included in the JSON object before anything is sent back to the client?

UPDATE: lucapette provides some good background about what's happening behind the scenes. Since there are times when I'd probably want all attributes returned, I ended up using the following code:

    format.json { render :json => @user.to_json(:only => ["id"])}

解决方案

render :json => @user

will call to_json on the @user object. And the to_json method will use the as_json method to do its work. So you can easily override the as_json to pass only what you want to the clients. Like in the following:

def as_json options={}
  {
    attr1: attr1,
    attr2: attr2
  }
end

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