[英]Angular2: How to create a loading directive for a button that call an async method?
我想創建一個按鈕/鏈接的指令,以便在單擊時通過加載器替換其內部文本,並在調用成功或失敗時重新設置其內部文本。
我是這樣開始的:
HTML:
<button (click)="update()" asyncLoader >Update</button>
指令:
import {
Directive,
Input,
ElementRef,
AfterViewInit,
Output,
EventEmitter,
HostListener,
} from '@angular/core';
@Directive({
selector: '[asyncLoader]'
})
export class ActionAsyncLoader {
text: string;
// @Output() valueChanged = new EventEmitter();
constructor(private elementRef: ElementRef) {
}
ngOnInit(){
this.text = this.elementRef.nativeElement.innerHTML;
// console.log('this.text', this.text);
}
@HostListener('click', ['$event.target']) onClick(btn) {
console.log('click async btn', btn);
btn.innerHTML = 'Loading';
}
}
這里點擊的元素用'Loading'替換它的文本。
問題:由於異步方法是在組件中設置的,如何從這里收聽回調?
現在,我只是在成功時發出一個事件而失敗,然后在指令中對它進行控制......我在指令中傳遞一個輸入以確保它與回調相匹配。
HTML:
<button (click)="update()" asyncLoader='updateXYZ' >Update</button>
指令:
@Directive({
selector: '[asyncLoader]'
})
export class ActionAsyncLoader {
@Input('asyncLoader') asyncLoader: string;
text: string;
// @Output() valueChanged = new EventEmitter();
constructor(private elementRef: ElementRef,
private eventsService: EventsService) {
eventsService.onCallbackAsync.subscribe(obj => this.onCallbackAsync(obj));
}
ngOnInit(){
this.text = this.elementRef.nativeElement.innerHTML;
}
@HostListener('click', ['$event.target']) onClick(btn) {
btn.innerHTML = 'Loading';
}
onCallbackAsync(obj){
console.log('onCallbackAsync', obj);
// check if directive matches the callback event
if (this.asyncLoader === obj.asyncLoader){
this.elementRef.nativeElement.innerHTML = this.text;
}
}
}
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