Angular reactive forms, adding and removing fields?

Question

while building crud app in angular 5 I\'ve come across with a question, how can I use the same form builder but change what form controls I get depending on what I want, adding

Answer 1

This is the most simple replication of add/remove for conditional angular form controls.

Seeing that you have a form with a checkbox control named someCheckboxControl watch for its boolean changes to add/remove the other control.

ngOnInit() {
   this.form.controls['someCheckboxControl'].valueChanges.subscribe(someCheckboxControlVal => {
       if (someCheckboxControlVal) {
           this.form.addControl('SomeControl', new FormControl('', Validators.required));
       } else {
           this.form.removeControl('SomeControl');
       }
   });
}

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