Angular 2 md-select 从 Observable 数组填充时不绑定 selected 值

Question

我有包含 md-select 的 angular2 反应形式，使来自 firebase 的用户 select doctor md-select 在呈现组件之前存在数据时工作正常，但如果数据到来async as observable 它不显示 selected 值

 doctors$:Observable< Doctor[] > = this.doctorService.findAllDoctors();
 

  constructor(private fb:FormBuilder , public doctorService : DoctorService 
  ,private cdr: ChangeDetectorRef )

  {    
   
 this.doctors$= this.doctorService.findAllDoctors();
  
this.form = this.fb.group({
      FullName: ['',Validators.required],
      Ext: [''],
      BirthDate: ['',Validators.required],
      Gender: ['',Validators.required],
      Phone: ['',[Validators.required]],
      doctorId: ['']

    });

<md-select formControlName="doctorId" ngControl="doctorId"  placeholder="Doctor"  >
      <md-option *ngFor="let p of doctors$ | async  " [value]="p.value">{{p.value}}</md-option>

    </md-select>

在此处输入代码

Answer 1

通过在异步加载选项数据后用选定值更新 md-select 解决

 ngOnInit() {
   
this.doctors$.subscribe(c=>{

    this.form.controls['doctorId'].patchValue(this.initialValue.doctorId);


});

Angular 2 md-select 从 Observable 数组填充时不绑定 selected 值

Angular 2 md-select don't bind selected value when populate from Observable array

observable

angularfire2

md-select

angular

angular-reactive-forms