Question

我是Backbone的新手。这是我的模特：

window.Image = Backbone.Model.extend({
  defaults: {
    id: "",
    url: ""
  }
});

window.ImageCollection = Backbone.Model.extend({
  model: Image
});

window.TargetDemoGraphic = Backbone.Model.extend({
  defaults: {
    targetDemographicId: "",
    targetDemographicDescription: "",
    checked: false
  }
});

window.TargetDemoGraphicCollection = Backbone.Collection.extend({
  model: TargetDemoGraphic,
  url: ServiceUrl + "/targetDemoGraphic/getAll"
});

window.Promotion = Backbone.Model.extend({
  url: function() {
    return ServiceUrl + "/promotion/get/" + encodeURIComponent(this.id);
  },
  defaults: {
    id: "",
    item: Item,
    start: "",
    end: "",
    title: "",
    newPrice: "",
    shortContent: "",
    detailContent: "",
    minLoyaltyPoint: "",
    membershipRequired: "",
    loyaltyPointRequired: "",
    loyaltyPointExchangeRequired: "",
    displayOnBanner: "",
    images: ImageCollection,
    bannerImage: Image,
    targetDemoGraphics: TargetDemoGraphicCollection
  }
}

window.PromotionCollection = Backbone.Collection.extend({
  model: Promotion,
  url: ServiceUrl + "/promotion/getAll" 
});

我的问题是在模板中打印出嵌套集合targetDemoGraphics时，集合的长度始终为0。我很困惑，因为嵌套的集合图像运行良好，它返回正确的值。

我的骨干观点：

window.PromotionReview = Backbone.View.extend({
initialize : function(options) {
    _.bindAll(this, 'beforeRender', 'render', 'afterRender');
    var _this = this;
    this.render = _.wrap(this.render, function(render) {
        _this.beforeRender();
        render();
        _this.afterRender();
        return _this;
    });
    this.render();
},

beforeRender : function() {
},

render : function() {
    var promotion = this.model.toJSON(); 
            //promotion.targetDemoGraphics.length returns = 4           
            //promotion.images.length = 4

            $(this.el).html(this.template(promotion));

    return this;
}

}）;

模板：

<% if (targetDemoGraphics != null && targetDemoGraphics.length > 0) { %>
                            <% for (var idx in targetDemoGraphics) { %>
                                    <p><%= targetDemoGraphics[i].label %></p>
                            <% } %>
                        <% } %>

// targetDemoGraphics.length = 0 ???

...

<% if (images != null && images.length > 0) { %>
                            <% for (var idx in images) { %>
                                    <a href="<%=ServiceUrl + '/images/' + images[idx].url %>" data-gallery>
                                        <img style="min-height:100px;height:100px;min-width:100px;width:100px;" src="<%=ServiceUrl + '/images/' + images[idx].url %>">
                                    </a>
                            <% } %>
                        <% } %>

// images.length = 4，正确值???

当打印出促销时，我得到2个targetDemoGraphics，一个包含4个对象，另一个是函数???

Answer 1

如果您正在嵌套集合，最好尝试使用一些Backbone扩展。检查Backbone Associations。使用某些扩展名可以帮助您绑定嵌套Models和Collections上的事件以及其他优势。

Backbone集合返回错误的长度

1 个答案: