angular - 在 Angular 2 的下拉列表中设置所选值

Question

我正在使用 FormBuilder 向数据库添加值。

 this.formUser = this._form.group({
   "firstName": new FormControl('', [Validators.required]),
  "lastName": new FormControl('', [Validators.required]),
  "externalCompany": new FormControl('', [Validators.required])
})

在添加这些值之前，我想将下拉菜单(外部公司)的值设置为我事先提交的值

<select class="form-control" id="companyExternal" formControlName="externalCompany" (ngModelChange)=onChangeExternalC($event)>
     <option value="" >Select existing company...</option>
     <option value="{{company}}" *ngFor="let company of externalCompanies">{{company}}</option>
     <option value="Company name..." >ADD ANOTHER...</option>
</select>

我试过了

this._commServe.addExternalCompany(company).subscribe((data) => {   
  this.formUser.value.externalCompany = company.CompanyName;
}, (error) => {
  this.errorMessage = <any>error;
})

我也尝试过使用 ngModel，但它也没有按预期工作。

在不借助 jQuery 的情况下设置此下拉列表的选定状态的最佳方法是什么

Answer 1

您可以在模型中具有选定值的选项上设置 selected 属性。

[attr.selected]="selectedExternalCompany"

使用 html 模板:

<select class="form-control" id="companyExternal" formControlName="externalCompany" (ngModelChange)=onChangeExternalC($event)>
     <option value="" >Select existing company...</option>
     <option value="{{company}}" 
         *ngFor="let company of externalCompanies" 
         [attr.selected]="selectedExternalCompany"
         >{{company}}</option>
     <option value="Company name..." >ADD ANOTHER...</option>
</select>

And in the component set the selectedExternalCompany when the select box change and use that as the model for instance.

这是基于答案 How to add conditional attribute in Angular 2?