Javascript knockoutjs绑定到主视图模型中所选子视图模型的ko.observatarray
在knockoutjs中,我有一个主视图模型,它有一组子视图模型,如下所示Javascript knockoutjs绑定到主视图模型中所选子视图模型的ko.observatarray,javascript,knockout.js,Javascript,Knockout.js,在knockoutjs中,我有一个主视图模型,它有一组子视图模型,如下所示 //apply binding on document ready $( document ).ready(function() { ko.applyBindings(new MainviewModel); }); //main view model, contains a child view models ko.observableArray var MainviewModel = function() {
//apply binding on document ready
$( document ).ready(function() {
ko.applyBindings(new MainviewModel);
});
//main view model, contains a child view models ko.observableArray
var MainviewModel = function()
{
// ko.observableArray of subviewmodels
this.subViewModels= ko.observableArray
([
new SubViewModel('A'),
new SubViewModel('B'),
new SubViewModel('C')
]);
//selected subviewmodel
this.selectedSubViewModel = ko.observable();
//set slected subviewmodel
this.selectSubViewModel = function(subviewmodel)
{
this.selectedSubViewModel = selectedSubViewModel(subviewmodel);
}
};
//child view model, contains ko.observableArray of models
var SubViewModel = function(key)
{
this.key = key;
//load items from json based on key value...
//ko.observableArray of subviewmodels
this.items=ko.observableArray([new Model("car","4 wheels"), new Model("plane","can fly")]);
//selected model
this.selectedModel = ko.observable();
//set selected model
this.selectModel = function(item)
{
this.selectedModel = selectedModel(item);
}
};
//model
var Model = function(word,defention)
{
//properties
this.word = word;
this.defention = defention;
};
在我的html中,我有两个列表更改第一个列表中的选择应该更改第二个列表的源,但是当我更改列表中的选择时,什么都不会发生,当我在chrome中调试时,我得到Uncaught ReferenceError:selectedSubViewModel未定义
<!--main view model list view-->
<div class="list-group" data-bind="foreach: subViewModels">
<a href="#" class="list-group-item" data-bind="css: {active: $parent.selectedSubViewModel() == $data}, click: $parent.selectSubViewModel.bind($parent)">
<h4 class="list-group-item-heading" data-bind="text: key"></h4>
</a>
</div>
<!--selected sub view model list view-->
<div class="list-group" data-bind="foreach: selectedSubViewModel.items">
<a href="#" class="list-group-item" data-bind="css: {active: $parent.selectedModel() == $data}, click: $parent.selectModel.bind($parent)">
<h4 class="list-group-item-heading" data-bind="text: word"></h4>
<p class="list-group-item-text" data-bind="text: defention"></p>
</a>
</div>
您的主要问题是您的
selectedSubViewModel
和selectedModel
不正确地试图设置您的selectedSubViewModel
和selectedModel
可观察对象
正确的语法是:
this.selectSubViewModel = function(subviewmodel)
{
this.selectedSubViewModel(subviewmodel);
}
this.selectModel = function(item)
{
this.selectedModel(item);
}
另请参见文档中的:
但是,它不会使您的代码正常工作,因为当首次执行foreach:selectedSubViewModel.items
绑定时selectedSubViewModel
将为null
,并且KO将找不到selectedSubViewModel.items
为了避免这种情况,可以使用包装foreach。在这种情况下,仅当selectedSubViewModel
中存在某些内容,并且您不必写入selectedSubViewModel时,才会呈现第二个列表。someproperty
足以写入foreach:items
等:
<!--selected sub view model list view-->
<!-- ko with: selectedSubViewModel -->
<div class="list-group" data-bind="foreach: items">
<a href="#" class="list-group-item"
data-bind="css: { active: $parent.selectedModel() == $data},
click: $parent.selectModel.bind($parent)">
<h4 class="list-group-item-heading" data-bind="text: word"></h4>
<p class="list-group-item-text" data-bind="text: defention"></p>
</a>
</div>
<!-- /ko -->
演示