Question

我是backbone.js的新手，我正在努力学习它。在下面的代码中，我希望我的名为“JokesCollection”的集合只接受添加“Joke”类的模型。我该怎么做到这一点？将“Collection”属性“model”设置为某个模型时，该集合是否应该只接受该模型类并确保同质性？不要缝。当我将“JokesCollection”类中的属性“model”分配给“Joke”时，它仍然接受添加类“Persson”的模型女巫不是我想要的。我只希望它接受添加“笑话”类的模型。

Joke = Backbone.Model.extend ({
    initialize: function(){
        console.log("Joke was created");
    },
    defaults: {
        joke : "",
        date : "0",
    }
});

JokesCollection = Backbone.Collection.extend({
    initialize: function(){
        console.log("JokesCollection was created");
    },
    model: Joke //  <=== Isn´t this supposed to ensure that the collection only accepts models of class "Joke"?
});

Person = Backbone.Model.extend ({
    initialize: function(){
        console.log("Person was created");
    },
    defaults: {
        username: "default",
        password: "default",
        email: "default"
    }
});



var person1 = new Person({username:"masterMind"});
var joke1 = new Joke({joke:"Girls are cute and funny hahahaha"});

jokesCollection = new JokesCollection();
jokesCollection.add(joke1);
jokesCollection.add(person1); // This adds a model of class "Person" to the collection. Witch is not what I want. It is not supposed to work! I want "jokesCollection" to only accept models of class "Joke".

console.log(jokesCollection.length); // length gets increased by 1 after adding "person1" to "jokesCollection". Again, it is no supposed to work from my point of view. I want "jokesCollection" to only accept models of class "Joke".
console.log(jokesCollection);

Answer 1

来自官方文档：

型号 collection.model

重写此属性以指定集合的模型类包含的内容。如果已定义，则可以传递原始属性对象（和数组）添加，创建和重置，属性将转换为适当类型的模型。

看起来必须重写这样的add方法：

add: function(models, options) {

    var modelClass = this.model;
        isProperIns = this.models.every.(function(model){
            return model instanceof modelClass;
        });

    if (!isProperIns) {
        throw new Error("Some of models has unacceptable type")
    } 

    return this.set(models, _.extend({merge: false}, options, addOptions));
}

Answer 2

Collection model属性的目的是不来限制Collection可以接受的模型。相反，该属性定义Model类，Collection在需要创建新Model时将使用该类。例如，当您将Model属性的对象文字（而不是实例化的Model）传递给JokesCollection.add时，或者当您fetch模拟到{{1}时}}，Backbone将使用JokesCollection作为Joke来实例化Model的新增内容。

有两种方法可以确保Collection仅填充JokesCollection个实例。第一种方法是永远不要直接向Joke添加Model个实例，而是：

A）通过JokesCollection

上的Joke调用来自服务器的新fetch

B）仅添加＆＃34; raw＆＃34; JokesCollection的{{1}}属性;不要添加实例化的Model

但是，如果您担心开发人员意外地向JokesCollection添加了非Model Joke，那么您的其他选择（由@Evgeniy首先建议）是覆盖Model Collection方法。与@ Evgeniy的答案不同，虽然我不建议重写Backbone的内部。相反，我会使用一个简单的覆盖，如果可能的话，只调用基本的Backbone方法：

JokesCollection

Backbone.js如何使集合只接受一类模型

2 个答案: