Angular 2+和Observables：无法绑定到“ ngModel”

Question

编辑：更新的Plunkr：http：//plnkr.co/edit/fQ7P9KPjMxb5NAhccYIq？p = preview

这部分工作：

<div *ngFor="let entry of entries | async">

  Label: {{ entry.label }}<br>

  Value: {{ entry.value }}

</div>

但是选择框出现问题，错误消息是：

无法绑定到“ ngModel”，因为它不是“ select”的已知属性

整个组件：

//our root app component

import {Component} from '@angular/core';

import {NgFor} from '@angular/common';

import {HTTP_PROVIDERS, Http} from '@angular/http';

import 'rxjs/Rx';

import {Observable} from 'rxjs/Rx';

@Component({

  selector: 'my-app',

  providers: [HTTP_PROVIDERS],

  template: `

  <select [(ngModel)]="selectValue" name="selectValue">

    <option *ngFor="let entry of entries | async" 

    [value]="entry.value">{{entry.label}}</option>

  </select>

    <div *ngFor="let entry of entries | async">

      Label: {{ entry.label }}<br>

      Value: {{ entry.value }}

    </div>

  `,

  directives: [NgFor]

})

export class App {

  entries: any = {};

  selectValue:any;

  constructor(private _http: Http) {

    this.entries = this._http.get("./data.json")

                            .map(res => res.json());

  }

}

和data.json

[

  {

    "timestamp": 0,

    "label": "l1",

    "value": 1

  },

  {

    "timestamp": 0,

    "label": "l2",

    "value": 2

  },

  {

    "timestamp": 0,

    "label": "l3",

    "value": 3    

  }

]