How to store multiple checkbox values in reactive form in angular2?

user_7403977 0
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I am working on angular2 application and getting problem in storing values of multiple check boxes in form field.

Type script

form : FormGroup;
cities = ["Mohali", "Chandigarh", "Ludhiana", "Amritsar"];
zip_codes = ["282001", "456123", "123456", "140412"];

constructor(private formBuilder : FormBuilder)
{
    this.form = this.formBuilder.group({
       cities   : this.formBuilder.array(["Mohali", "Amritsar"]),
       zip_codes : this.formBuilder.array(["456123"])
    });
}

HTML 

<div *ngFor="let city of cities">
    <input type="checkbox" formControlName="cities" value="city">
    <span>{{city}}</span>
</div>

<div *ngFor="let zipCode of zip_codes">
    <inbput type="checkbox" formControlName="zip_codes" value="zipCode">
     <span>{{zipCode}}</span>
</div>

I want to store checked cities and zip_codes in form field and when I have default values in form field then the values are in array will be checked automatically.

angular2-forms angular
2 Answers

I liked very much the answer of @yurzui But had an issue with getting the values back .. So..

My solution - solved it for Angular 5 with Material View
The connection is through the

formArrayName="notification"

(change)="updateChkbxArray(n.id, $event.checked, 'notification')"

This way it can work for multiple checkboxes arrays in one form. Just set the name of the controls array to connect each time.

constructor(
  private fb: FormBuilder,
  private http: Http,
  private codeTableService: CodeTablesService) {

  this.codeTableService.getnotifications().subscribe(response => {
      this.notifications = response;
    })
    ...
}


createForm() {
  this.form = this.fb.group({
    notification: this.fb.array([])...
  });
}

ngOnInit() {
  this.createForm();
}

updateChkbxArray(id, isChecked, key) {
  const chkArray = < FormArray > this.form.get(key);
  if (isChecked) {
    chkArray.push(new FormControl(id));
  } else {
    let idx = chkArray.controls.findIndex(x => x.value == id);
    chkArray.removeAt(idx);
  }
}
<div class="col-md-12">
  <section class="checkbox-section text-center" *ngIf="notifications  && notifications.length > 0">
    <label class="example-margin">Notifications to send:</label>
    <p *ngFor="let n of notifications; let i = index" formArrayName="notification">
      <mat-checkbox class="checkbox-margin" (change)="updateChkbxArray(n.id, $event.checked, 'notification')" value="n.id">{{n.description}}</mat-checkbox>
    </p>
  </section>
</div>

At the end you are getting to save the form with array of original records id's to save/update. The UI View

The relevat part of the json of the form

Will be happy to have any remarks for improvement.

Here is the Gist

user_1856050
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