angular ControlValueAccessor检查是否使用ngModel绑定

import { Component, forwardRef } from '@angular/core';
import { ControlValueAccessor, NG_VALUE_ACCESSOR } from '@angular/forms';

@Component({
  selector: 'app-custom-input',
  template: `<input type="text" (input)="onChange($event.target.value)" (blur)="onTouched()">`,
  providers: [
    {
      provide: NG_VALUE_ACCESSOR,
      useExisting: forwardRef(() => CustomInputComponent),
      multi: true
    }
  ]
})
export class CustomInputComponent implements ControlValueAccessor {
  private onChange: (_: any) => void = () => {};
  private onTouched: () => void = () => {};

  writeValue(value: any): void {
    // 实现写入值的逻辑
  }

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

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

  setDisabledState?(isDisabled: boolean): void {
    // 实现设置禁用状态的逻辑
  }

  // 检查是否使用了 ngModel
  isNgModelUsed(): boolean {
    return this.onChange !== undefined && this.onTouched !== undefined;
  }
}