Angular2 - 指令不更新模型

Question

我在一个包含数值的 html 输入框上有一个指令。当用户将数字粘贴到文本框中时，我有一个“清除”数字的指令(去除逗号、美元符号等)。清理代码似乎工作正常，但是即使文本框显示我的清理值，我的模型也没有更新清理值。

如何使用新值更新我的模型？

Plnkr here

这是一个精简的例子:

app.ts

@Component({
  selector : 'my-app',
  template : `
  <div>
    <br/>
    <br/>
    <p>Stack Overflow person - give focus to text box and then lose focus by clicking elsewhere in the screen. <br/>The model is not updated.</p>
    <br/>Model value: {{ balanceAmount }}
    <br/>
    <br/>
    <input type="text" [(ngModel)]="balanceAmount" myCurrencyFormatter  /><br/>
  </div>
  `,
})
export class App {
  name:string;
  constructor(private mycurpipe: MyCurrencyPipe) {
    this.balanceAmount = 1234567.89;
  }
}

Currency-Formatter-Directive.ts

@Directive({ selector: "[myCurrencyFormatter]" })
export class MyCurrencyFormatterDirective implements OnInit {

  private el: any;

  constructor(
    private elementRef: ElementRef,
    private currencyPipe: MyCurrencyPipe
  ) {
    this.el = this.elementRef.nativeElement;

  }

  ngOnInit() {
    this.el.value = this.currencyPipe.transform(this.el.value);
  }

  @HostListener("focus", ["$event.target.value"])
  onFocus(value) {
    this.el.value = this.currencyPipe.parse(value); // opossite of transform
  }

  @HostListener("blur", ["$event.target.value"])
  onBlur(value) {
    this.el.value = this.cleanNumber(value); //"987654" ;//this.currencyPipe.transform(value);
  }
  
  cleanNumber (value: number) {
    return 8888888; // clean logic goes here, removed for plunk example
  }
  

}

Plnkr here

Answer 1

您需要为您的模型添加Emitter。这是在 Angular 2 中实现双向绑定(bind)的方法。看看行 @Output() ngModelChange = new EventEmitter(); 以及我如何使用此变量将更改发送给调用者。

import { Directive, HostListener, ElementRef, OnInit, EventEmitter, Output } from "@angular/core";
import { MyCurrencyPipe } from "./my-currency.pipe";

@Directive({ selector: "[myCurrencyFormatter]" })
export class MyCurrencyFormatterDirective implements OnInit {

  private el: any;
  @Output() ngModelChange = new EventEmitter();

  constructor(
    private elementRef: ElementRef,
    private currencyPipe: MyCurrencyPipe
  ) {
    this.el = this.elementRef.nativeElement;

  }

  ngOnInit() {
    this.el.value = this.currencyPipe.transform(this.el.value);
  }

  @HostListener("focus", ["$event.target.value"])
  onFocus(value) {
    this.el.value = this.currencyPipe.parse(value); // oposite of transform
    this.ngModelChange.emit(this.el.value);
  }

  @HostListener("blur", ["$event.target.value"])
  onBlur(value) {
    this.el.value = this.cleanNumber(value); //"987654" ;//this.currencyPipe.transform(value);
    this.ngModelChange.emit(this.el.value);
  }
  
  cleanNumber (value: number) {
    return 8888888;
  }

}