具有特定类型的 Backbone.Js 集合 [英] Backbone.Js Collection with Specific Types

问题描述

我有一个叫做 History 的 BackboneJS 集合，它可以包含几个 Backbone JS 模型之一(从 HistoryItem 扩展到 Backbone.Model)，我试图找到一种在加载时重新创建它的方法，不幸的是它似乎是 BackboneJS 集合只能在特定型号指定，例如

I have a BackboneJS collection called History which can contain one of several Backbone JS models (which extend from HistoryItem which extends from Backbone.Model), I trying to find a way to have this recreated when loading, unfortunately it seems BackboneJS collection can only specify at particular model e.g.

HistoryCollection = Backbone.Model.extend({
  model: app.models.HistoryItem
})

我真正需要做的是确定每种类型，这是我想做的

What I really need to do is determine this per type, here is what I'd like to do

 HistoryCollection = Backbone.Model.extend({   
  model: function(item) {
       return app.models[item.type];   } })

在我 fork Ba​​ckbone 来实现这个之前有什么想法吗?(即一个可以带函数的集合模型属性)

Any ideas before I fork Backbone to implement this? (i.e. a collection model attribute being able to take a function)

推荐答案

在萤火虫中玩耍……想出了一种方法，您可以覆盖集合的解析方法而不是指定模型.您的解析实现基本上变成了一个简单的工厂，用于用您想要的模型填充集合:

Playing around in firebug.. came up with an approach where you can override the parse method of collection instead of specifying the model. Your parse implementation basically becomes a simple factory for filling the collection with models that you want:

var BaseModel  = Backbone.Model.extend({
    meth: function(){ return 'Base method'; },
});

var SubModel = BaseModel.extend({
    meth: function(){ return 'Sub1 method'; }
});

var SubModel2 = BaseModel.extend({
    meth: function(){ return 'Sub2 method'; }
});

var ModelCollection = Backbone.Collection.extend({
    parse: function(data){
        var self = this;
        data.forEach(function(item){
            switch(item.type){
            case 1:
                self.add(new SubModel(data));
                break;
            case 2:
                self.add(new SubModel2(data));
                break;
            default:
                self.add(new BaseModel(data))
        }
});
    }
});

//Example Use
x = new ModelCollection;
x.parse([{type: 1},{type: 2}, {type: 99}]);
x.map(function(e){ return e.meth();});

这篇关于具有特定类型的 Backbone.Js 集合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！