将模板项绑定到KnockoutJS中数组的索引 [英] Bind template item to the index of the array in KnockoutJS

问题描述

我需要根据它们在Jquery插件列表中出现的位置在KnockoutJS模板中命名<div>'s，如下所示:

<div id="item1">...</div>
<div id="item2">...</div>
<div id="item3">...</div>

是否有一种方法可以使用KnockoutJS绑定到数组中项目的索引? 如果我不得不使用ROWINDEX将这些数据添加到数据库的select中，那将是一种耻辱.

解决方案

更新:KO现在支持$index上下文变量，您可以在foreach(或template中使用foreach参数)中使用).文件: http://knockoutjs.com/documentation/binding-context.html

如果您可以使用jQuery模板{{each}}，则可以使用以下方法:

<div data-bind="template: 'allItemsTmpl'"></div>
<script id="allItemsTmpl" type="text/html">
    {{each(i, item) items}}
    <div data-bind="attr: { id: 'item' + i }">
        <input data-bind="value: name" />
    </div>
    {{/each}}
</script>

如果必须使用foreach选项，则可以执行以下操作:

<div data-bind="template: { name: 'itemTmpl', foreach: items }"></div>
<button data-bind="click: addItem">Add Item</button>
<script id="itemTmpl" type="text/html">
    <div data-bind="attr: { id: 'item' + ko.utils.arrayIndexOf(viewModel.items, $data) }">
        <input data-bind="value: name" />
    </div>
</script> 

这些天来，我更喜欢为我的observableArray创建一个订阅，该订阅只需要对数组进行一次遍历，并创建/设置该项目上可观察的索引.像:

//attach index to items whenever array changes
viewModel.tasks.subscribe(function() {
    var tasks = this.tasks();
    for (var i = 0, j = tasks.length; i < j; i++) {
       var task = tasks[i];
        if (!task.index) {
           task.index = ko.observable(i);  
        } else {
           task.index(i);   
        }
    }
}, viewModel);

此处提供示例: http://jsfiddle.net/rniemeyer/CXBFN/

或者您可以采用这个想法并扩展observableArrays以提供indexed函数，该函数允许您仅通过调用myObservableArray.indexed()进行设置.

这里是一个示例: http://jsfiddle.net/rniemeyer/nEgqY/

I need to name the <div>'s in a KnockoutJS template according to the position that they appear in the list for a Jquery plugin like so:

<div id="item1">...</div>
<div id="item2">...</div>
<div id="item3">...</div>

Is there a way to bind to the index of the item in the array using KnockoutJS? It would be a shame if I had to add this data to the select on the database using ROWINDEX.

解决方案

update: KO now supports a $index context variable that you can use within a foreach (or template with foreach param). Docs: http://knockoutjs.com/documentation/binding-context.html

If you are okay with using jQuery Templates {{each}}, then something like this will work:

<div data-bind="template: 'allItemsTmpl'"></div>
<script id="allItemsTmpl" type="text/html">
    {{each(i, item) items}}
    <div data-bind="attr: { id: 'item' + i }">
        <input data-bind="value: name" />
    </div>
    {{/each}}
</script>

If you had to use the foreach option, then something like this would work:

<div data-bind="template: { name: 'itemTmpl', foreach: items }"></div>
<button data-bind="click: addItem">Add Item</button>
<script id="itemTmpl" type="text/html">
    <div data-bind="attr: { id: 'item' + ko.utils.arrayIndexOf(viewModel.items, $data) }">
        <input data-bind="value: name" />
    </div>
</script> 

Edit: these days I prefer to create a subscription to my observableArray that only has to take one pass through the array and create/set an index observable on the item. Like:

//attach index to items whenever array changes
viewModel.tasks.subscribe(function() {
    var tasks = this.tasks();
    for (var i = 0, j = tasks.length; i < j; i++) {
       var task = tasks[i];
        if (!task.index) {
           task.index = ko.observable(i);  
        } else {
           task.index(i);   
        }
    }
}, viewModel);

Sample here: http://jsfiddle.net/rniemeyer/CXBFN/

or you can take this idea and extend observableArrays to provide an indexed function that would allow you to set this up just by calling myObservableArray.indexed().

Here is a sample: http://jsfiddle.net/rniemeyer/nEgqY/

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