Question

在Collection的上下文中，我想基于包含模型数据的某个对象来检索模型实例，但我不想对idAttribute进行硬编码。

当你已经拥有一个模型实例时，Backbone会让事情变得简单，你可以只访问它的.id属性并将其排序，但我似乎无法找到另一种方式，创建模型实例只是为了获得idAttribute。

例如：

var Cat = Backbone.Model.extend({
  defaults: {
    name: '',
    age: null
  },

  idAttribute: 'name'
});

var PushCollection = Backbone.Collection.extend({
  initialize: function () {
    coll = this;
    somePushConnection.on('deleted', function (deleted) {
      _.each(deleted, function (obj) {
        // obj being something like: {name: 'mittens', age: 302}
        var model = coll.get(obj[coll.model.idAttribute]); // Can't do this!
        if (model) { model.destroy(); }
      });
    });
  }
});

var Cats = PushCollection.extend({
  model: Cat
});

Answer 1

您应该可以通过模型的原型访问它：

Model.prototype.idAttribute

或在您的示例代码中

var model = coll.get(obj[coll.model.prototype.idAttribute]);

Answer 2

也许我误解了这个问题，但你不能使用Collection.where()方法吗？

来自Backbone文档：

其中 collection.where(attributes)

返回所有模型的数组   在与传递的属性匹配的集合中。有用的简单   过滤的情况。
var friends = new Backbone.Collection([
  {name: "Athos",      job: "Musketeer"},
  {name: "Porthos",    job: "Musketeer"},
  {name: "Aramis",     job: "Musketeer"},
  {name: "d'Artagnan", job: "Guard"},
]);

var musketeers = friends.where({job: "Musketeer"});

alert(musketeers.length);

所以，在你的示例代码中：

var PushCollection = Backbone.Collection.extend({
  initialize: function () {
    coll = this;
    somePushConnection.on('deleted', function (deleted) {
      _.each(deleted, function (obj) {
        // obj being something like: {name: 'mittens', age: 302}
        var model = coll.where(obj);
        if (model) { model.destroy(); }
      });
    });
  }
});

查找集合模型的idAttribute

2 个答案: