如何根据集合属性设置Backbone模型的默认值 [英] How to set Backbone model's defaults based on collection attribute

问题描述

我需要所有新的MenuItem模型从父系列中获取菜单属性。
这是一个不起作用的基本示例（因为在MenuItem的默认函数中未定义this.collection）

I need all new MenuItem models to have menu attribute from parent collection. Here is a basic example that doesn't work (because this.collection is undefined in MenuItem's defaults function)

var MenuItem, Menu, menu;

MenuItem = Backbone.Model.extend({
  defaults: function() {
    return {
      menu: this.collection.name
    }
  },

  // Fake Backbone sync
  sync: function(method, model, options) {
    if(typeof model.cid != 'undefined') {
      var cid = model.cid;
      model.unset('cid').set({id:cid}, {silent:true});
    }
    options.success(model);
  }

});

Menu = Backbone.Collection.extend({
  model: MenuItem,
  initialize: function(options) {
    this.name = options.name;
  }
});

menu = new Menu({name: "footer"});

menu.create({title: "Page", url: "/page"}, {
  success: function(model){
    console.log(model.get("menu")) // expect to be "footer"
  }
})

推荐答案

我已经设法通过重写集合的创建方法来修复它，我仍然不确定这是否是正确的方法。

I've managed to fix it by overriding collection's create method, I'm still unsure if this is the right way to go.

create: function(attributes, options) {
  return Backbone.Collection.prototype.create.call(
    this,
    _.extend({menu: this.name}, attributes),
    options
  );
}

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