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我刚刚开始使用 ControlValueAccessor，到目前为止我真的很喜欢它，但我遇到了一个我无法解决的问题..

@Component({
  selector: 'app-project',
  templateUrl: './project.component.html',
  styleUrls: ['./project.component.scss'],
  changeDetection: ChangeDetectionStrategy.OnPush
})
export class ProjectComponent implements ControlValueAccessor, OnInit {

  @Input('companyNumber') set companyNumber(companyNumber: string) {
    this._companyNumber = companyNumber;
  }

  ctrlErrorStateMatcher = new CtrlErrorStateMatcher();
  private _companyNumber: string;

  constructor(
    private readonly _costCenterService: CostCenterService,
    @Optional() @Self() public ngControl: NgControl,

  ) {
    if (this.ngControl != null) {
      // Setting the value accessor directly (instead of using the providers) to avoid running into a circular import.
      this.ngControl.valueAccessor = this;
    }
  }

  onTouched = (_value?: any) => { };
  onChanged = (_value?: any) => { };

  writeValue(val: string): void {
    if (val) {
      this.ngControl.control?.setValue(val);
    }
  }

  registerOnChange(fn: any): void {
    this.onChanged = fn;
  }

  registerOnTouched(fn: any): void {
    this.onTouched = fn;
  }

  ngOnInit() {
    this.ngControl.control.setAsyncValidators(this.validate.bind(this));
    this.ngControl.control.updateValueAndValidity();
  }
  validate(control: AbstractControl): Observable<ValidationErrors | null> {
    const isValid = this._costCenterService
      .validateProject(control.value, this._companyNumber)
      .pipe(
        map(response => {
          return response ? null : { inValidProjectNumber: true };
        })
      );
    return isValid;
  }
}

export class CtrlErrorStateMatcher implements ErrorStateMatcher {
  isErrorState(control: FormControl): boolean {
    return !!(control && control.invalid);
  }
}

因此，当我更改输入中的值（不仅仅是触发 (blur) ）时，这一切都可以正常工作。但是当@Input 更改时，它不会更新状态（触发 validate() ）...

如果我然后更改输入中的值，它确实可以工作......删除 OnPush 可以解决问题，但不是我想要做的......

更新：模板

<mat-form-field appearance="outline">
  <mat-label>Label</mat-label>
  <input matInput #projectInput [value]="ngControl.value" [formControl]="ngControl?.control"
    (change)=" onChanged($event.target.value)" (blur)="onTouched()" [errorStateMatcher]="ctrlErrorStateMatcher" />
  <mat-error *ngIf="ngControl.hasError('inValidProjectNumber')">
    Error
  </mat-error>
</mat-form-field>
4

1 回答 1

0

我发现了这个 git 问题https://github.com/angular/angular/issues/12378

所以对我来说，解决方案是添加一个 finalize 管道并使用 markForCheck()

  validate(control: AbstractControl): Observable<ValidationErrors | null> {
    const isValid = this._costCenterService
      .validateProject(control.value, this._companyNumber)
      .pipe(
        map(response => {
          return response ? null : { inValidProjectNumber: true };
        }),
        finalize(() => this.changeDetectorRef.markForCheck())
      );
    return isValid;
  }
于 2020-10-16T12:26:51.740 回答