如何在Rails中构建由多个模型组成的JSON响应

How to build a JSON response made up of multiple models in Rails

一，理想的结果

我有User和Item模型。我想构建一个如下所示的JSON响应：

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

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

但是，我的User和Item模型具有更多的属性。我找到了使它工作的方法，但是请注意，这还不是很漂亮...请帮助...

更新

下一部分包含原始问题。最后一部分显示了新的解决方案。

我的骇客

home_controller.rb

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class HomeController < ApplicationController

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

end

观察文件

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# 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

妈你看没有更多的骇客！

改写as_json

ActiveRecord :: Serialization#as_json文档非常稀疏。这是摘要：

1 2	as_json(options = nil) [show source]

有关to_json与as_json的更多信息，请参见关于在Rails 2.3.5中覆盖to_json的可接受答案。

该代码没有技巧

user.rb

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class User < ActiveRecord::Base

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

end

item.rb

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class Item < ActiveRecord::Base

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

end

home_controller.rb

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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

已编辑为使用as_json而不是to_json。请参阅如何在Rails中覆盖to_json？详细说明。我认为这是最好的答案。

您可以在控制器中呈现所需的JSON，而无需帮助程序模型。

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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

确保将ActiveRecord::Base.include_root_in_json设置为false，否则您将在\\'user \\'内获得一个\\'user \\'属性。不幸的是，数组似乎没有将options传递给每个元素，因此collect是必需的。