如何在foreach的Knockout组件中访问数组成员? [英] How do I access array members in a Knockout component in a foreach?
问题描述
我无法使Knockout组件正常工作-在使用$index
访问的foreach
期间,我似乎无法使其正确绑定到ViewModel上的数组成员.
I am having trouble getting a Knockout component to work - i can't seem to get it to bind properly to the members of an array on my ViewModel during a foreach
accessed using $index
.
在这个小提琴中,您会明白我的意思.
In this Fiddle you will see what I mean.
有两个小视图模型:
function OtherThingViewModel(thingString){
this.thingString = ko.observable(thingString);
}
function ThingViewModel(thingNumber, thing){
this.thingNumber = ko.observable(thingNumber);
}
在主viewModel中创建实例:
Instances are created in the main viewModel:
function ViewModel(){
var self = this;
this.things = [
new ThingViewModel(1),
new ThingViewModel(2),
new ThingViewModel(3)
];
this.otherThings = [
new OtherThingViewModel("a Thing"),
new OtherThingViewModel("another Thing"),
new OtherThingViewModel("some Thing")
];
this.specialThing = ko.unwrap(this.things)[0];
this.specialOtherThing = ko.unwrap(this.otherThings)[0];
};
然后我有一个组件:
ko.components.register('combinedthing-component', {
template:
'<div>'
+ ' <h3 data-bind="text: \'Thing \' + thing.thingNumber()"></h3>'
+ ' <p>'
+ ' <label>thingNumber: <input data-bind="value: thing.thingNumber" /></label>'
+ ' <span data-bind="text: thing.thingNumber" />'
+ ' </p>'
+ ' <p>'
+ ' <label>thingString: <input data-bind="value: otherThing.thingString" /></label>'
+ ' <span data-bind="text: otherThing.thingString" />'
+ ' </p>'
+ ' <p data-bind="text: JSON.stringify(ko.unwrap(otherThing))"></p>'
+ '</div>'
});
用于显示两个视图模型中的数据.
for displaying data from the two view models.
在HTML中,我可以成功使用该组件,并使用foreach
,我可以将两个对象组合在一起:
In the HTML I can successfully use the the component and using a foreach
I can combine the two objects:
<h1>1 component</h1>
<combinedthing-component params="thing: specialThing, otherThing: specialOtherThing"></combinedthing-component>
<h1>Foreach</h1>
<!-- ko foreach: things -->
<div>
<h3 data-bind="text: 'Thing ' + thingNumber()"></h3>
<p>
<label>thingNumber <Input data-bind="value: thingNumber" /></label>
<span data-bind="text: thingNumber" />
</p>
<p>
<label>thingString: <input data-bind="value: $root.otherThings[$index()].thingString" /></label>
<span data-bind="text: $root.otherThings[$index()].thingString" />
</p>
</div>
<!-- /ko -->
但是如果我尝试将两者结合在一起-将things
与foreach
循环,然后使用$ index访问otherThings
数组并将其绑定到组件:
but if I try and combine the two - looping thorugh things
with the foreach
and then accessing the otherThings
Array using $index and binding these to the component:
<h1>Many Components</h1>
<!-- ko foreach: things -->
<combinedthing-component params="thing: $data, otherThing: $root.otherThings[$index()]"></combinedthing-component>
<!-- /ko -->
然后,当我在otherThing
中获得一个对象(通过ko.toJSON绑定证明)时,其属性未绑定到input
和span
.
Then while I get an object in otherThing
(as proved by the ko.toJSON binding) its properties are not binding to the input
and span
.
有什么作用?
推荐答案
问题是由于使用"Web组件"语法时如何将参数传递到组件中而引起的.通过params=""
传递的对象将转换为相关的可观察对象(计算的).在后台,$root.otherThings[$index()]
本质上成为此实现function () { return $root.otherThings[$index()]; }
的计算可观察到的结果.
The problem is due to how params are passed into a component when using the "web component" syntax. The objects passed through params=""
get transformed into dependent observables (computeds). Behind the scenes, $root.otherThings[$index()]
essentially becomes a computed observable with this implementation function () { return $root.otherThings[$index()]; }
.
最简单的方法是在引用otherThing
时添加所需的内容.这将确保您始终使用实际的otherThing
而不是可观察的包装.
The simplest way is to get what you want is to add a ko.utils.unwrapObservable
when referencing otherThing
. This will ensure that you're always working with the actual otherThing
instead of an observable wrapping it.
<label>thingString: <input data-bind="value: ko.utils.unwrapObservable(otherThing).thingString" /></label>
<span data-bind="text: ko.utils.unwrapObservable(otherThing).thingString" />
执行此解包的理想位置是组件注册的视图模型部分.
The ideal place to do this unwrapping would be in view model part of the component registration.
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