更改Aurelia中的数组顺序,奇怪的行为 [英] Change Array Order in Aurelia, weird behaviour
问题描述
我正在尝试构建自定义元素来管理简单列表,重命名项目并更改其顺序。不幸的是,我注意到一些奇怪的行为实际上很难确定。
I am trying to build a custom element to manage simple lists, renaming the items and changing their order. Unfortunately I'm noticing some weird behavior that's actually really hard to pin down.
- 输入输入似乎没有被识别为变化让Aurelia更新项目
- 在页面加载后输入/更改一个项目然后通过这些方法更改其在数组中的位置时,项目的索引似乎丢失(变为-1) 。如果项目未通过输入字段更改,则数组中的索引将被正确识别并且排序有效。
有没有已知的数组,绑定甚至是子元素的问题?为获得理想的行为而接受过测试的战斗是什么?非常感谢!
Are there any known issues with arrays, binding and maybe even child elements? What are the battle tested approached to get the desired behavior? Thanks a lot!
父元素
...
<list items.bind="list"></list>
...
列表元素
<template>
<div class="input-group" repeat.for="item of items">
<input value.bind="item" class="input" type="text" placeholder="Item" autofocus>
<a click.delegate="deleteItem(item)">X</a>
<a click.delegate="moveItemUp(item)">^</a>
<a click.delegate="moveItemDown(item)">v</a>
</div>
<a click.delegate="addItem()">Add Item</a>
列出JS
export class List {
@bindable({defaultBindingMode: bindingMode.twoWay}) items;
constructor() {}
addItem() {
this.items.push('new')
}
deleteItem(item) {
let i = this.items.indexOf(item)
this.items.splice(i, 1)
}
moveItemUp(item) {
let i = this.items.indexOf(item)
if (i === 0) return
let temp = item
this.items.splice(i, 1)
this.items.splice(i - 1, 0, temp)
}
moveItemDown(item) {
let i = this.items.indexOf(item)
if (i === this.items.length) return
let temp = item
this.items.splice(i, 1)
this.items.splice(i, 0, temp)
}
}
推荐答案
repeat.for
有几个可以利用的上下文变量。 [文档]
repeat.for
has several contextual variables you can leverage of. [Documentation]
Gist演示: https://gist.run/?id= 1c8f78d8a774cc859c9ee2b1ee2c97f3
- 当前项目的正确位置可以通过
$ index
上下文变量而不是items.indexOf(item)
。 - 输入的数据绑定值将通过将
item
传递给items.slice(newIndex,item)<来保留/ code>。
- Current item's correct position can be determined by using
$index
contextual variable instead ofitems.indexOf(item)
. - Databound values of inputs will be preserved by passing
item
toitems.slice(newIndex, item)
.
如果需要观察数组更改,CollectionObserver可能非常适合。更多详细信息:观察Aurelia中的对象和阵列 。
If you need to observe array changes, CollectionObserver could be a great fit for that. More details here: Observing Objects and Arrays in Aurelia.
list.js
import { bindable, bindingMode } from 'aurelia-framework';
export class List {
@bindable({defaultBindingMode: bindingMode.twoWay}) items;
constructor() {}
addItem() {
this.items.push(`New Item ${this.items.length + 1}`);
}
deleteItem(i) {
this.items.splice(i, 1);
}
moveItemUp(i, item) {
if (i === 0)
return;
this.moveItem(i, i - 1, item);
}
moveItemDown(i, item) {
if (i === this.items.length - 1)
return;
this.moveItem(i, i + 1, item);
}
moveItem(oldIndex, newIndex, item) {
this.items.splice(oldIndex, 1);
this.items.splice(newIndex, 0, item);
}
}
list.html
<template>
<div class="input-group" repeat.for="item of items">
<input value.bind="item" class="input" type="text" placeholder="Item" autofocus> |
<a click.delegate="deleteItem($index)"><i class="fa fa-close"></i></a> |
<a click.delegate="moveItemUp($index, item)"><i class="fa fa-arrow-up"></i></a> |
<a click.delegate="moveItemDown($index, item)"><i class="fa fa-arrow-down"></i></a>
</div>
<a click.delegate="addItem()">Add Item</a>
</template>
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