CODEWITHSUNDEEP
angularangular6angular-reactive-forms
Anuj TBE
Anuj TBE

Reputation: 9790

Angular 6: Set empty form array field

I'm using Angular 6. and Reactive form builder to build a form.

ngOnInit() {
    this.landingPageForm = this.formBuilder.group({
      title: new FormControl('', [
        Validators.required
      ]),
      description: new FormControl('', [
        Validators.required
      ]),
      faqs: this.formBuilder.array([
        this.createFaqFields()
      ]),
    });

    this._setFormValue();
}

createFaqFields(): FormGroup {
  return this.formBuilder.group({
    question: new FormControl(),
    answer: new FormControl()
  });
}

private _setFormValue() {
    if (this.product) {
      this.landingPageForm.setValue({
        title: this.product.info.title,
        description: '',
        faqs: [],
      });
    }
  }

I have to prefill few fields initially and faqs is an array field in which new fields are generated dynamically by calling 

onClickAddFaqField(): void {
  this.faqFields = this.landingPageForm.get('faqs') as FormArray;
  this.faqFields.push(this.createFaqFields());
}

Initially, there is only one faq input field in HTML and that empty. But it is giving an error

"Must supply a value for form control at index: 0.

How can I initialize the array input field empty?

Upvotes: 0

Views: 7172

Answers (4)

Ihor Khomiak
Ihor Khomiak

Reputation: 1179

landingPageForm.controls.faqs.clear();

Upvotes: 0

Anuj TBE
Anuj TBE

Reputation: 9790

After trying all the answers and examples from different sources. This is how I solved it.

private _setFormValue() {
  if (this.product) {
    this.landingPageForm.setValue({
      title: this.product.info.title,
      description: '',
      faqs: [{
        question: '',
        answer: ''
      }],
    });
  }
}

Added question, answer with empty value as the first object to the faqs field.

Upvotes: 0

Yuvaranjani
Yuvaranjani

Reputation: 310

Instead of using FormControl() in createFaqFields(), try like this, 

ngOnInit() {
      this.landingPageForm = this.formBuilder.group({
        title:'',
        description: '',
        faqs: this.formBuilder.array([this.createFaqFields()])
      });
        this._setFormValue();
    }


    createFaqFields(): FormGroup {
      return this.formBuilder.group({
        question: '',
        answer: ''
      });
    }

Upvotes: 0

PeS
PeS

Reputation: 4039

I guess, I would do this:

ngOnInit() {
  this.landingPageForm = this.formBuilder.group({
    title: new FormControl('', [Validators.required]),
    description: new FormControl('', [Validators.required]),
    faqs: this.formBuilder.array([])
  });

  // Try this
  // OTOH why when you set that to [] in _setFormValue()?
  this.landingPageForm.get('faqs').push(this.createFaqFields());

  this._setFormValue();
}

createFaqFields(): FormGroup {
  return new FormGroup({
    question: new FormControl(null),
    answer: new FormControl(null)
  });
}

Upvotes: 1

Related Questions