选择 - 请选择 - 作为一种形式角4.0 HTML内部下拉的默认

Question

我有几个下拉列表形式里面，但是我不能够让 - 请选择那些下拉菜单的默认选项。

我得到完全平原和空白下拉列表。点击后我们可以看到项目已绑定里面。

HTML

<form novalidate (ngSubmit)="onSubmit(projectinformationFrm)" [formGroup]="projectinformationFrm">
    <select [(ngModel)]="selectedOrganization" placeholder="Organization" formControlName="OrganizationId" (change)="onSelectOrgEdit($event.target.value)" class="form-control">

        <option *ngFor="let org of OrganizationList" [ngValue]="org .OrganizationId" [selected]="org.OrganizationId==selectedOrganization">
        {{ org .OrganizationName }}
        </option>
    </select>

    <div>
        <a class="btn btn-default" (click)="modal.dismiss()"><span class="glyphicon glyphicon-remove"></span>Cancel</a>
        <button type="submit" class="btn btn-primary"><span class="glyphicon glyphicon-save"></span>Save</button>
    </div>

</form>

Component.ts

public selectedOrganization: number=0;


LoadListforProjectManager(): void {
    try {

        this._service.get(URL)
            .subscribe(data => { this.OrganizationList = data; },
                error => this.msg = <any>error);
    }
    catch (e) {
        this._errorLogService.LogError(e);
    }
}

我也越来越0,"--Please Select--"从存储过程列表中的第一项。

Answer 1

相反，让列表中的第一项为请选择，分量模板创建它。也不要与ReactiveForms方法一起使用[(ngModel)]。事情是这样的：

<form novalidate (ngSubmit)="onSubmit(projectinformationFrm)" [formGroup]="projectinformationFrm">
    <select placeholder="Organization" formControlName="OrganizationId" (change)="onSelectOrgEdit($event.target.value)" class="form-control">

    <option value="null" disabled>Please select</option>

    <option *ngFor="let org of OrganizationList" [ngValue]="org .OrganizationId" [selected]="org.OrganizationId==selectedOrganization">
      {{ org .OrganizationName }}
    </option>
  </select>

  <div>
    <a class="btn btn-default" (click)="modal.dismiss()"><span class="glyphicon glyphicon-remove"></span>Cancel</a>
    <button type="submit" class="btn btn-primary"><span class="glyphicon glyphicon-save"></span>Save</button>
  </div>

</form>

以下是为您的参考一Working Sample StackBlitz。