javascript - Knockout Observable 数组长度始终为 0

Question

在 customerOverview View 模型中调用任何可观察对象的长度时，我收到的长度为零。当绑定(bind)随数据更新时，可观察对象中存在数据，但长度保持为 0。基本 View 模型“CustomerCentral”正确返回长度。我需要“CustomerOverview”中一些可观察对象的长度来执行一些条件语句。

HTML 绑定(bind)

<ul class="nav nav-list">
      <li class="nav-header">Contacts</li>
      <!--ko  if: customerOverview.contacts().length == 0-->
      <li>No contacts associated with this customer</li>
       <!-- /ko -->
      <!--ko  foreach: customerOverview.contacts()-->
      <li>
      <a data-bind="click: $root.customerOverview.viewContact"><i class="icon-chevron-                        right single pull-right">
       </i><span data-bind="text: FirstName"></span><span data-bind="text: LastName"></span>
      </a></li>
      <!-- /ko -->
</ul>

JS

function CustomerOverview() {
        var self = this;        

        self.contacts = ko.observableArray([]);           

        self.getCustomerContacts = function () {
            requestController = "/CRM/CustomerCentral/CustomerContacts";
            queryString = "?id=" + self.customer().Id();
            $.ajax({
                cache: false,
                type: "GET",
                dataType: "json",
                url: baseURL + requestController + queryString,
                headers: { "AuthToken": cookie },
                success:
                        function (data) {
                            if (data.data.length > 0) {

                                self.contacts(ko.mapping.fromJS(data.data));

                                console.log(self.contacts().length);
                            }
                        }
            });
        };
};
   function CustomerCentral() {

        var self = this;

        self.customerOverview = ko.observable(new customerOverview());
};

var vm = new CustomerCentral();
    ko.applyBindings(vm);

控制台命令:vm.customerOverview().contacts().length0

------------------------解决方案---------------- --- observableArray.push()

问题原来是这一行:

  self.contacts(ko.mapping.fromJS(data.data));

解决方案:将 .push() 添加到此可以使数组的 length 属性增加。我原以为 ko.mapping 会处理这个问题，但事实并非如此。将变量更改为 observable 没有任何效果。

 $.each(data.data, function () {
          self.contacts.push(ko.mapping.fromJS(this));
           console.log(self.contacts().length);
                                    });

Answer 1

我认为你的问题是你的 customerOverview 属性没有被观察到

尝试:

 self.customerOverview = ko.observable(new CustomerOverview());

或

 self.customerOverview = ko.computed(function(){
       return new CustomerOverview();
 });

工作样本:

http://jsfiddle.net/dvdrom000/RHhmY/1/

html

<span data-bind="text: customerOverview().contacts().length"></span>
<button data-bind="click: customerOverview().getCustomerContacts">Get contacts</button>

js

function CustomerOverview() {
        var self = this;        

        self.contacts = ko.observableArray([]);           

        self.getCustomerContacts = function () {
            self.contacts.push(1);
            self.contacts.push(2);
            self.contacts.push(3);            
        };
};
   function CustomerCentral() {

        var self = this;
        // Is this a correct way. Am I breaking something with this?
        self.customerOverview = ko.observable(new CustomerOverview());
};

var vm = new CustomerCentral();
    ko.applyBindings(vm);