将类的Ruby数组转换为JSON [英] convert Ruby array of class into JSON

问题描述

我有这样的Ruby数据结构:

I have a Ruby data structure as such:

class Albums
    attr_accessor :title, :url

    def initialize(title, url)
        @title = title
        @url = url
    end
end

class Albumlist < Albums
    attr_accessor :id, :albums

    def initialize(id)
        @id = id
        @albums = Array.new
    end
end

然后我制作了一个专辑列表数组，看起来像(使用.inspect方法):

And I made an array of Albumlist which looks like (using .inspect method):

[#<Albumlist:0x8db6390 @id="abc",@albums=[
     #<Albums:0x8db6098 @title="123", @url="test">,
     #<Albums:0x8db5fe4 @title="456", @url="test">
 ]>,
 #<Albumlist:0x8f4042c @id="def", @albums=[
     #<Albums:0x8f49f2c @title="Untitled Album", @url="test">
 ]>
]

我不确定这个数组是否看起来还可以，但是一旦我在这个数组上使用了.to_json或JSON.generate()方法，我得到的就是:

I am not sure if this array looks okay but once I used the method .to_json or JSON.generate() on this array, all I get is:

["#<Albumlist:0x8db6390>","#<Albumlist:0x8f4042c>"]

看起来Ruby将引用"返回到对象实例. 我想将此数组转换为JSON，

It looks like Ruby returns the "reference" to the object instances. I want to convert this array in JSON which should look like

[
    {
            "id":"abc"
            "albums":[
                    {
                            "title":"123",
                            "url":"test"
                    },
                    {
                            "title":"456",
                            "url":"test"
                    }
            ]
    },
    {
            "id":"def"
            "albums":[
                    {
                            "title":"Untitled Album",
                            "url":"test"
                    }
            ]
    }
]

而且我相信我缺少一些东西，例如将数组转换为某种中间对象?

and I believe I am missing something, such as converting the array into some kind of intermediate object?

替代解决方案

在相册列表类中定义to_json方法，如下所示:

Define a to_json method in class Albumlist as such:

def to_json(*a)
    {
        "id" => @id,
        "albums" => @albums
    }.to_json(*a)
end

并改用它..

推荐答案

在这里可以正常工作，可能您不是在正确的时机应用该方法，让我们尝试一下，首先，着眼于像这样的数组:

Here it works, probably you are not applying the method on the right moment, let's try it, first, focusing on the array with something like this:

require 'rubygems'
require 'active_support/all'
class Albums
    attr_accessor :title, :url

    def initialize(title, url)
        @title = title
        @url = url
    end
end

class Albumlist < Albums
    attr_accessor :id, :albums

    def initialize(id)
        @id = id
        @albums = Array.new
    end
end

a = Albums.new("a", "www.a.com")
b = Albums.new("b", "www.b.com")
c = Albums.new("c", "www.c.com")

list_of_albums_list = Array.new
list_a = Albumlist.new(1)
list_b = Albumlist.new(2)

list_a.albums << a
list_a.albums << b
list_b.albums << c

list_of_albums_list << list_a
list_of_albums_list << list_b
puts list_of_albums_list.to_json

输出为:

[{"albums":[{"title":"a","url":"www.a.com"},{"title":"b","url":"www.b.com"}],"id":1},{"albums":[{"title":"c","url":"www.c.com"}],"id":2}]

因此该方法可以按预期工作.

therefore the method works as expected.

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