Angular 2: update FormControl validator after valueChanges

Question

Is there a way to update Validtorsa FormControl object? I have FormGroupwhere one input is a selection field when the value of the selection field changes. I want another FormControl in my FormGroup to change the validator.

Here is my method subscribeToFormChanges()from my FormGroup component:

private appIdRegexes = {
    ios: /^[a-zA-Z][a-zA-Z0-9]*(\.[a-zA-Z0-9\-]+){2,}$/,
    android: /^([a-zA-Z])[a-zA-Z0-9_]*(\.[a-zA-Z][a-zA-Z0-9\-]*){2,}$/,
    any: /^any$/
  };

private subscribeToFormChanges(): void {
    const myFormValueChanges$ = this.appsForm.valueChanges;
    myFormValueChanges$.subscribe(x => {
      const platform = this.appsForm.controls['platform'].value;
      const appId = this.appsForm.controls['appId'].value;

      if (this.appIdRegexes[platform]) {
        this.appsForm.controls['appId'] = new FormControl(appId, Validators.pattern(this.appIdRegexes[platform].source));
      }
    });
  }

And here is the html template:

<div class="row" [formGroup]="appsForm">
  <div class="form-group col-xs-6">
    <label>Platform</label>

    <select id="licensePlatform" class="form-control"
            formControlName="platform">
      <option *ngFor="let platform of licensePlatforms" [value]="platform">
        {{platform}}
      </option>
    </select>

    <small [hidden]="appsForm.controls.platform.valid">
      Platform is required
    </small>
  </div>

  <div class="form-goup col-xs-6">
    <label>App ID</label>
    <input type="text" class="form-control" formControlName="appId">
    <small [hidden]="appsForm.controls.appId.valid">
      Please use the right ID format
    </small>
  </div>
</div>

When I implement a method subscribeToFormChanges(), as shown here, it appsForm.controls.appId.valueno longer updates when I write to the input field. The value is initially updated.

Answer 1

, valueChanges , setValidators() appId. .

:

 private subscribePlatformChanges() {
    const platformCtrl = this.appsForm.controls['platform'];
    const changes$ = platformCtrl.valueChanges;

    changes$.subscribe(platform => {
      this.appsForm.controls['appId'].setValidators([Validators.pattern(this.appIdRegexes[platform].source),
                                                    Validators.required]);
      this.appsForm.controls['appId'].updateValueAndValidity();
    });
  }

Answer 2

FormGroup, - updateValueAndValidity FormControl.

this.appsForm FormGroup:

this.appsForm.controls.forEach(control => control.updateValueAndValidity());

Answer 3

<select id="licensePlatform" class="form-control"
            formControlName="platform"  (change)="update($event.target.value)" >
      <option selected="selected" disabled="disabled" value="">Select Card Type</option>
      <option *ngFor="let platform of licensePlatforms" [value]="platform" >
        {{platform}}
      </option>
    </select>

,

update(value){
      if(value){
        (<FormControl>this.appsForm.controls['platform']).setValue(value, {onlySelf: false});
        const appId = this.appsForm.controls['appId'].value;
        if (this.appIdRegexes[value]) {
        this.appsForm.controls['appId'] = new FormControl(appId, Validators.pattern(this.appIdRegexes[value].source));
      }
    };

  }

, . , .