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Question

我的这段代码一直在抛出错误，我不明白为什么。

var id = $(ev.currentTarget).data("id");
    var item = ItemCollection.getByCid(id);
    alert(item.get("ItemCode"));
    var qty = 1;
    var cartcollection = new CartCollection();
    cartcollection.add( item );
    CartListView.render();
    var itemcode = cartcollection.where({ItemCode: item.get("ItemCode")});
    if( itemcode.length > 0 ){ alert("success"); }

所以我想做的是检查CartCollection是否已经具有相同的模型，如果是，则它应该只更新模型的Qty atrib。现在基于该代码返回CartCollection不是函数或不是构造函数。为什么会这样！？有任何想法吗？感谢

更新

我正在使用主干，需要，KendoUI网格和下划线，所以我的代码就是这样：

itemlist_view.js

define([
'jquery',
'underscore',
'backbone',
'model/item_model',
'model/cart_model',
'collection/item_collection',
'collection/cart_collection',
'view/cart/cartlist_view',
'text!templates/items/itemlist.html'
 ],function($, _, Backbone, Item, Cart, ItemCollection, CartCollection, CartListView, ItemListTemplate){

var ItemListView = Backbone.View.extend({
el: $("#mainContainer"),
events:{
    "click #itemListContainer li" : "AddToCart"
},
initialize: function(){
  this.model = Item;
  this.collection = ItemCollection;
  this.collection.bind("reset", this.render );
},
render: function(){
  var data = {
    items: ItemCollection.models
  }
  var compiledTemplate = _.template( ItemListTemplate , data);
  $("#itemContainer").html( compiledTemplate );
},
AddToCart:function(ev){
    ev.preventDefault();
    var id = $(ev.currentTarget).data("id");
    var item = ItemCollection.getByCid(id);
    alert(item.get("ItemCode"));
    var qty = 1;
    var cartcollection = new CartCollection();
    cartcollection.add( item );
    CartListView.render();
    var itemcode = cartcollection.where({ItemCode: item.get("ItemCode")});
    if( itemcode.length > 0 ){ alert("success"); }
}
});
return new ItemListView;
});

cart_collection.js

define([
'underscore',
'backbone',
'model/cart_model'
],function(_, Backbone, Cart){
var CartCollection = Backbone.Collection.extend({
    model: Cart,
  initialize: function(){

  }
});
return new CartCollection;
 });

cartlist_view.js

define([
 'jquery',
 'underscore',
 'backbone',
 'model/cart_model',
 'collection/cart_collection',
 'text!templates/cart/cartlist.html'
 ], function($, _, Backbone, Cart, CartCollection, CartListTemplate){

var Model = kendo.data.Model,
    ObservableArray = kendo.data.ObservableArray;

function wrapBackboneModel(backboneModel, fields) {
    return Model.define({
        fields: fields,
        init: function(model) {
            if (!(model instanceof backboneModel)) {
                model = new backboneModel(model);
            }

            Model.fn.init.call(this, model.toJSON());
            this.backbone = model;
        },
        set: function(field, value) {
            Model.fn.set.call(this, field, value);

            this.backbone.set(field, value);
        }
    });
}

function wrapBackboneCollection(model) {
    return ObservableArray.extend( {
        init: function(collection) {
            ObservableArray.fn.init.call(this, collection.models, model);

            this.collection = collection;
        },

        splice: function(index, howMany) {
            var itemsToInsert, removedItemx, idx, length;

            itemsToInsert = Array.prototype.slice.call(arguments, 2);

            removedItems = kendo.data.ObservableArray.fn.splice.apply(this, arguments);

            if (removedItems.length) {
                for (idx = 0, length = removedItems.length; idx < length; idx++) {
                    this.collection.remove(removedItems[idx].backbone);
                }
            }

            if (itemsToInsert.length) {
                for (idx = 0, length = itemsToInsert.length; idx < length; idx++) {
                    this.collection.unshift(itemsToInsert[idx].backbone);
                }
            }

            return removedItems;
        }
    });
}

kendobackboneCollection = wrapBackboneCollection;
kendobackboneModel = wrapBackboneModel;


var CartListView = Backbone.View.extend({
el: $("#cartContainer"),

initialize: function(){
  this.collection = CartCollection;
  this.model = Cart;
  this.collection.bind("change", this.render );
},
render: function(){
  console.log("here");
  this.el.html(CartListTemplate);
  var CartWrapper = kendobackboneModel(Cart, {
     ItemCode: { type: "string" },
     ItemDescription: { type: "string" },
     RetailPrice: { type: "string" },
     Qty: { type: "string" },
  });
  var CartCollectionWrapper = kendobackboneCollection(CartWrapper);

  this.$("#grid").kendoGrid({
    editable: true,
    toolbar: ["create"],
    columns: ["ItemDescription", "Qty", "RetailPrice"],
    dataSource: {
      schema: {model: CartWrapper},
      data: new CartCollectionWrapper(CartCollection),
     }
  });

},

});
return new CartListView;
});

Answer 1

我认为问题在于你是双重实例CartCollection。也就是说，cart_collection.js会返回new CartCollection()，而itemlist_view.js会再次使用var cartcollection = new CartCollection();对其进行实例化。

将该行更改为var cartcollection = CartCollection;并查看其行为。显然，您也可以删除cartcollection变量并将其用法替换为CartCollection。

另一方面，我会认真考虑不从你的new CartCollection()返回cart_collection.js。这感觉非常糟糕，因为您只能使用该集合的一个实例。此外，开发人员并不明白他们正在收回集合的实例，而不是它的构造函数。

我建议您返回CartCollection instaed，然后使用itemlist_view.js在new CartCollection()文件中对其进行实例化。这样，您可以在以后需要时实例化更多这些集合。

同样建议cartlist_view.js返回new CartListView()。

集合不是函数，或者集合不是Backbone中的构造函数

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1 个答案: