JSON数据转换为骨干模型子集合 [英] Converting JSON data to Backbone Model with child Collection

问题描述

我正在与具有某些属性定义本身以及一个PlaylistItem集合播放列表对象的工作

I am working with a Playlist object which has some properties defining itself as well as a PlaylistItem collection.

当我从服务器接收数据，我得到了我的客户端的成功方法的JSON响应：

When I receive data from my server, I get its JSON response in my client-side success method:

success: function (data) {
    console.log("JSON data:", data);

    playlists = _.map(data, function (playlistConfig) {
        return new Playlist(playlistConfig);
    });

    ...
}

在这里，我将我JSON数据到播放列表对象。每个播放列表对象是Backbone.Model。

Here, I convert my JSON data into Playlist objects. Each Playlist object is a Backbone.Model.

下面是我的数据的外观：

Here's how my data looks:

和这里的播放列表构造是什么样的：

And here's what the Playlist constructor looks like:

return function(config) {
    var playlist = new Playlist(config);

    return playlist;
};

var Playlist = Backbone.Model.extend({
    defaults: function() {
        return {
            id: null,
            userId: null,
            title: 'New Playlist',
            selected: false,
            position: 0,
            shuffledItems: [],
            history: [],
            items: Backbone.Collection.extend({
                model: PlaylistItem
            })
        };
    },
    ...
}

我的问题：

如果我创建一个默认播放列表对象，它与PlaylistItem空Backbone.Collection初始化。不过，如果我创建一个已定义的集合播放列表对象，我得到一个基本的阵列，而不是一个Backbone.Collection。这是因为我使用JSON数据还没有被转化为骨干实体尚未服务器的工作。这些数据扩展了播放列表中的默认值，并覆盖Backbone.Collection实体。

If I create a Playlist object with defaults, it initializes with an empty Backbone.Collection for PlaylistItem. However, if I create a Playlist object with an already-defined collection, I get a basic array and not a Backbone.Collection. This is because I am working with JSON data from the server which has not been converted to Backbone entities yet. That data is extended over the Playlist's defaults and overwrites the Backbone.Collection entity.

什么是用填充Backbone.Collection初始化一个适当的方式？我可以写在初始化code哪些检查我的项目阵列的类型，如果它不是一个Backbone.Collection我可以创建一个新的Backbone.Collection并添加项目，然后用新的替换旧阵列，但似乎真的hoakey。

What is a proper way to initialize with a populated Backbone.Collection? I could write code in Initializes which checks the type of my items array and if it is not a Backbone.Collection I could create a new Backbone.Collection and add the items to it and then replace the old array with the new one, but that seems really hoakey.

推荐答案

没有定义PlalistItems集合中的默认值，但事前。
然后，在你的播放列表模式，像这样创建初始化方法：

Don't define your PlalistItems Collection inside defaults, but beforehand. Then, create an initialize method on your Playlist Model like so:

var PlaylistItems = Backbone.Collection.extend({
   ...
});

var Playlist = Backbone.Model.extend({
    initialize: function() {
        this.set('items', new PlaylistItems(this.items));
    },

    defaults: function() {
        return {
            id: null,
            userId: null,
            title: 'New Playlist',
            selected: false,
            position: 0,
            shuffledItems: [],
            history: [],
            items: []  // don't define your PlaylistItems Collection here
        };
}
});

点击这里，查看小提琴： http://jsfiddle.net/georgedyer/r2XKb/
（你需要打开控制台看到集合）

Check out the fiddle here: http://jsfiddle.net/georgedyer/r2XKb/ (you'll need to open the console to see the collection)

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