我创建了一个类似于的自定义结构指令ngFor
。当我尝试使用它时<template>
元素语法时,模板内的绑定有效,但当我使用 * 语法时,绑定无效。
<!-- working -->
<template edit [editOf]="values" let-val="val">
<table >
<span>This is using template syntax {{val}}</span>
</table>
</template>
<!-- not working -->
<table *edit="let val1 of values">
<span>This uses star syntax {{val1}}</span>
</table>
这里是链接 http://plnkr.co/edit/ON0YvkJOsgiaWYG11mcb?p=preview对于这个问题。
我究竟做错了什么?
Update:我想,现在我明白是怎么回事了。这let-val
属性设置不正确val
用于绑定的对象,但我需要整个对象。所以let-val
不应在模板中分配任何值,然后我必须使用用作 viewRef 中绑定源的对象来更新 context.$implicit 。
Working plnkr在这里。 http://plnkr.co/edit/yi58UGgPPY71J4co5Mhx?p=preview
感谢@robisim74
尝试这个:
import { ChangeDetectorRef,
Directive,
Input,
DoCheck,
IterableDiffer,
IterableDiffers,
TemplateRef,
ViewContainerRef,
EmbeddedViewRef} from "@angular/core";
@Directive({
"selector":"[edit][editOf]"
})
export class EditableTableDirective implements DoCheck {
private collection:any;
private differ:IterableDiffer;
private viewMap:Map<any,EmbeddedViewRef> = new Map<any,EmbeddedViewRef>();
constructor(
private changeDetector:ChangeDetectorRef,
private differs:IterableDiffers,
private template:TemplateRef,
private viewContainer:ViewContainerRef){
}
@Input() set editOf(coll:any){
this.collection = coll;
if (coll && !this.differ) {
this.differ = this.differs.find(coll).create(this.changeDetector);
}
}
ngDoCheck() {
if (this.differ) {
const changes = this.differ.diff(this.collection);
if (changes) {
changes.forEachAddedItem((change) => {
const view = this.viewContainer.createEmbeddedView(this.template, change.item);
view.context.$implicit = change.item;
this.viewMap.set(change.item, view);
});
changes.forEachRemovedItem((change) => {
const view = this.viewMap.get(change.item);
const viewIndex = this.viewContainer.indexOf(view);
this.viewContainer.remove(viewIndex);
this.viewMap.delete(change.item);
});
}
}
}
}
然后修正模板:
<table *edit="let item of values">
<span>This uses star syntax {{item.val}}</span>
</table>
我关注了这篇文章:http://teropa.info/blog/2016/03/06/writing-an-angular-2-template-directive.html http://teropa.info/blog/2016/03/06/writing-an-angular-2-template-directive.html
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