Rails中的无表模型JSON序列化 [英] Tableless model JSON serialization in Rails

问题描述

我有一个无桌子的模型(就像在#219 railscast中显示的那样):

I have tableless model (like it was shown in #219 railscast):

class MyModel
  include ActiveModel::Conversion
  extend ActiveModel::Naming

  attr_accessor :attr1, :attr2, :attr3, :attr4

  private
    def initialize(attr1 = nil)
      self.attr1 = attr1
    end

    def persisted?
      false
    end
end

然后我正在尝试在控制器中呈现JSON:

Then I'm trying to render JSON in controller:

@my_model = MyModel.new
render json: @my_model.to_json(only: [:attr1, :attr2])

但是它使用模型的所有属性呈现JSON.

but it renders JSON with all the attributes of the model.

我尝试添加

include ActiveModel::Serialization

但它并没有更改呈现的JSON.

but it didn't change rendered JSON.

如何仅使用无表模型的必要属性来呈现JSON?

How can I render JSON with only necessary attributes of my tableless model?

我正在使用Rails 3.2.3

I'm using Rails 3.2.3

更新

谢谢，伙计们.看来您几乎是正确的.我结合了您的解决方案并得到了:

Thanks, guys. It seems you're all almost right. I combined your solutions and got this:

型号:

include ActiveModel::Serialization

...

def to_hash
  {
    attr1: self.attr1,
    attr2: self.attr2,
    ...
  }
end

控制器:

render json: @my_model.to_hash.to_json(only: [:attr1, :attr2])

我真的不知道谁的答案会被接受.

I really don't know whose answer to be accepted.

更新2

突然出现了新的陌生感.属性之一是哈希数组.就像这样:

Suddenly new strangeness appeared. One of the attributes is array of hashes. It was like this:

attr1: [[{name: "name", image: "image"}, {name: "name", image: "image"}],
        [{name: "name", image: "image"}, {name: "name", image: "image"}]]

但是现在它丢失了所有内容，看起来像这样:

But now it lost all its content and looks like this:

attr1: [[{}, {}], [{}, {}]]

也许有人知道如何解决?

Maybe anyone know how to fix it?

更新3 :)

Erez Rabih的回答有所帮助.使用slice代替to_json解决了该问题.因此，最终的解决方案是:

Erez Rabih's answer helped. Using slice instead of to_json solved the problem. So, final solution is:

render json: @my_model.to_hash.slice(:attr1, :attr2)

推荐答案

我知道这不是直截了当的，但是如何:

I know it isn't straight forward but how about:

render :json => @my_model.attributes.slice(:attr1, :attr2)

还需要将属性方法定义为:

You will also be required to define an attributes method as:

def attributes
   {:attr1 => self.attr1.....}
end

感谢评论者.

这篇关于Rails中的无表模型JSON序列化的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！