Valuechanges事件可观察到的rxjs不会在Angular中捕获

发布于 2025-02-06 07:21:14 字数 718 浏览 1 评论 0原文

在构造函数中，我有：

this.step1FormGroup = this.formBuilder.group({
  firstLastName: new FormControl('')

});

this.step1FormGroup.get('firstLastName').valueChanges.pipe(
  map((a) => {
    console.log('oy!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!');
    return a;
  })
);

在模板中，我有一个：

<form [formGroup]="step1FormGroup">
  <ng-template matStepLabel>Fill out your name</ng-template>
  <mat-form-field>
    <input matInput
      placeholder='Last name, First name'
      formControlName='firstLastName'>
  </mat-form-field>
  
</form>

但是我没有捕获Valuechanges，因此我没有获得console.log输出。如何在管道后使用subscribe（）方法解决此问题？

原文

In constructor I have:

this.step1FormGroup = this.formBuilder.group({
  firstLastName: new FormControl('')

});

this.step1FormGroup.get('firstLastName').valueChanges.pipe(
  map((a) => {
    console.log('oy!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!');
    return a;
  })
);

and in template I have this:

<form [formGroup]="step1FormGroup">
  <ng-template matStepLabel>Fill out your name</ng-template>
  <mat-form-field>
    <input matInput
      placeholder='Last name, First name'
      formControlName='firstLastName'>
  </mat-form-field>
  
</form>

but I am not catching the valueChanges, so I am not getting the console.log output. How can I fix this, without using the subscribe() method after the pipe?

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忘你却要生生世世 2025-02-13 07:21:15

valueechanges函数返回可观察的，因此，如果您是pipe> pipe ing in and and and and One in and ocal>工作，在某个地方，您需要订阅该可观察的。

请记住，observables默认情况下，懒惰，如果您不订阅，则不会获得数据。

this.step1FormGroup.get('firstLastName').valueChanges.pipe(
  map((a) => {
    console.log('oy!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!');
    return a;
  })
).subscribe(); // here

另外，我建议将该逻辑从构造函数移至ngoninit，这就是所有数据初始化的地方。

The valueChanges function returns an Observable, so it's fine if you are pipeing and doing some operations in there, but in order to actually make it work, somewhere, you need to subscribe to that observable.

Remember, observables by default, are lazy, you don't get the data if you don't subscribe.

this.step1FormGroup.get('firstLastName').valueChanges.pipe(
  map((a) => {
    console.log('oy!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!');
    return a;
  })
).subscribe(); // here

Also, I recommend moving that logic from your constructor to ngOnInit, that's where all the data initialization should be handled.

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