Angular 2和Angularfire2中的三向绑定

Question

我正在尝试使用AngularFire 2(2.0.0-beta.2)将输入元素三路绑定到Angular.js 2(2.0.0-rc.4)中的firebase数据库.

我有一个非常简单的HTML:

<form (ngSubmit)="onSubmit()" #commentForm="ngForm">
  <input [(ngModel)]="model.author" type="input" name="author" required>
</form>

在我的组件中,为了保存和检索此输入的内容到firebase,我有一个这样的实现:

export class CommentFormComponent implements OnInit, AfterViewInit {
  @ViewChild("commentForm") form;
  // http://stackoverflow.com/questions/34615425/how-to-watch-for-form-changes-in-angular-2

  firebaseInitComplete = false;
  model: Comment = new Comment("", "");
  firebaseForm: FirebaseObjectObservable<Comment>;

  constructor(private af: AngularFire) { }

  ngAfterViewInit() {
    this.form.control.valueChanges
      .subscribe(values => {
        // If we haven't get the initial value from firebase yet,
        // values will be empty strings. And we don't want to overwrite
        // real firebase value with empty string on page load
        if (!this.firebaseInitComplete) { return; }

        // If this is a change after page load (getting initial firebase value) update it on firebase to enable 3-way binding
        this.firebaseForm.update(values);
      });
  }

  ngOnInit() {
    this.firebaseForm = this.af.database.object("/currentComment");
    // Listen to changes on server
    this.firebaseForm.subscribe(data => {
      this.firebaseInitComplete = true; // Mark first data retrieved from server
      this.model = data;
    });
  }    
}

上面的代码工作,当用户实时输入内容时,我能够读取firebase的初始firebase值和更新值.

但是有一个手动逻辑来检查this.firebaseInitComplete和添加ngAfterViewInit以监听更改感觉有点不对,我只是在破解它工作.

是否有更好的三向绑定实现,组件内的逻辑更少？

Answer 1

七个月后,我有一个答案..扩展ngModel语法..

<input [ngModel]='(model|async)?.author' (ngModelChange)="model.update({author: $event})">

[]块是一个getter,而()块是一个setter.由于模型的getter实际上是展开FirebaseObjectObservable,因此必须使用FirebaseObjectObservable的绑定来设置它.