angular - 如何从 Observable 中提取数据？

Question

如何提取数据并将其传递到表单？

user$!: Observable<UserI>

ngOnInit(): void {
  this.user$ = this.userService.getPerson();
  this.initializeForm();
}

initializeForm(): void {
  this.form = this.fb.group({
    fullName: new FormControl(?, Validators.required),
  });
}

Answer 1

您有多种选择:

您可以在加载数据时初始化表单，也可以使用空/默认值初始化表单并在加载数据时设置更新值。

方法一:

ngOnInit(): void {
  this.userService.getPerson().pipe(
      tap(user => this.initializeForm(user))
  ).subscribe();
}

initializeForm(user: UserI): void {
  this.form = this.fb.group({
    fullName: new FormControl(user.fullName, Validators.required),
  });
}

---

方法2:

ngOnInit(): void {
  this.initializeForm();
  this.userService.getPerson().pipe(
      tap(user => {
          this.form.get('fullName').setValue(user.FullName);
      })
  ).subscribe();
}

initializeForm(): void {
  this.form = this.fb.group({
    fullName: new FormControl('', Validators.required),
  });
}

我个人更喜欢为我的控件创建字段:

readonly fullName = new FormControl('', Validators.required);

ngOnInit(): void {
  this.initializeForm();
  this.userService.getPerson().pipe(
      tap(user => {
          this.fullName.setValue(user.FullName);
      })
  ).subscribe();
}

initializeForm(): void {
  this.form = this.fb.group({
    fullName: this.fullName,
  });
}

然后我可以直接访问它们，包括在 html 中

<input [formControl]="fullName"/>
<span *ngIf="fullName.errors?.required">Fullname is required</span>