Angular2 @ ViewChildren / @ ViewQuery的QueryList时不会更新动态地添加第二个层次的孩子 [英] Angular2 @ViewChildren/@ViewQuery's QueryList not updated when dynamically adding second level children
问题描述
我想打一个目录树,并有机会获得所有项目,无论高低,但@ ViewChildren / @ ViewQuery的QueryList没有更新我的时候动态地添加第二个层次的孩子:
I want to make a directory tree and to have access to all items regardless of the level, but @ViewChildren/@ViewQuery's QueryList is not updated when I dynamically add second level children:
import {bootstrap} from 'angular2/platform/browser';
import {Component, View, QueryList,ViewQuery, Query,ViewChildren} from 'angular2/core';
@Component({
selector: 'item',
})
@View({
template: `
<button (click)="addChild()">Add Child</button>
<ng-content></ng-content>
<div *ngFor="#child of children; #i = index">
<item> {{child.name}}</item>
</div>
`
})
export class Item {
//public children = [ { name: 'Child 1', age: 22 } ];
public children = [];
addChild() {
this.children.push({ name: 'Child' + (this.children.length + 1), age: 18 });
}
}
@Component({
selector: 'my-app'
})
@View({
directives: [Item],
template: `
<button (click)="addParent()">Add Parent</button>
<div *ngFor="#user of users; #i = index">
<item #item> {{user.name}}</item>
</div>
`
})
export class AppComponent {
public users = [
{ name: 'Parent 1', age: 22 }
];
@ViewChildren(Item, {descendants: true}) itemList: QueryList<Item>;
constructor() {}
ngAfterViewInit() {
console.log(this.itemList);
this.itemList.changes.subscribe(() => console.log(this.itemList));
}
addParent() {
this.users.push({ name: 'Parent ' + (this.users.length + 1), age: 18 });
}
}
bootstrap(AppComponent);
这是当我addParent()时,我的addChild更新的更新,但不是()。它看起来像QueryList只认购了顶级的变化。任何想法如何使它工作?
It is updated when I addParent(), but not updated when I addChild(). It looks like QueryList is subscribed only for top level changes. Any ideas how to make it work?
推荐答案
我认为它的东西比使用 @ViewChildren
/ 更一般@ViewQuery
。
I think that it's something more general than the use of @ViewChildren
/ @ViewQuery
.
在事实上,它是Angular2处理变化检测的方式。我的意思是对象中的更新不会引起变化的检测,但如果你更新整个引用,它的作用。
In fact, it's the way Angular2 handles the change detection. I mean updates within objects don't trigger change detection but if you update the whole reference, it does.
所以,你需要重构了一下你的 removeDynamic
方法:
So you need to refactor a bit your removeDynamic
method:
addChild() {
this.children.push({ name: 'Child' + (this.children.length + 1), age: 18 });
this.children = this.children.slice();
}
addParent() {
this.users.push({ name: 'Parent ' + (this.users.length + 1), age: 18 });
this.users = this.users.slice();
}
请参阅关于使用片这个答案
方法:
- Populating another array from array - Javascript
下面是关于这种行为的角度队了答案: https://github.com/角/角/问题/ 6458 。
Here is the answer from the Angular team regarding this behavior: https://github.com/angular/angular/issues/6458.
希望它可以帮助你,
蒂埃里
Hope it helps you, Thierry
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