问显示ngModel inside文本输入

EN

 <div class="input-group mb-3">
      <div class="input-group-prepend">
        <span class="input-group-text text-white" style="background-color:#03a9f4">Product ID</span>
      </div>
      <input type="text" class="form-control" [(ngModel)]="productID" name="productID" readonly="true" style="background-color: white">
 </div>

 private productID: string;

  private initData() {
    this.productID = "12345"; //TODO REST call for data
  }

  ngOnInit() {
    this.initData();
  }