How to change ngbDatepicker date format from JSON to YYYY/MM/DD

Question

I'm working with ngbDatepicker this is giving me JSON date format like:

{ year: 2019, month: 6, day: 9 }

How can I convert this into YYYY/MM/DD? I'm using Angular 7.

My Code is as below:

<div class="input-group">
   <input class="form-control" placeholder="YYYY-MM-DD"
          (click)="d2.toggle()" (ngModelChange)="onDateSelection($event,'ToDate');"  name="d2" #c2="ngModel" [(ngModel)]="toDate" ngbDatepicker #d2="ngbDatepicker">
         <div class="input-group-append">
          <button class="btn btn-outline-secondar" 
             (click)="d2.toggle()" type="button">
           <i class="fa fa-calendar" aria-hidden="true"></i>
          </button>
         </div>
 </div>

Answer 1

There two important class to manage ngbDate. one it's for formatting the date: a DateParserFormater, and another to change the value you get/send from/to a ngb-datepicker: a DateAdapter.

So, you can create a customDateAdapter and a customDateParserFormatter. But, don't worry about the names. ist only two injectable class like, e.g.

For customDateAdapter

@Injectable()
export class CustomDateAdapter {
  fromModel(value: string): NgbDateStruct
  {
     if (!value)
      return null
     let parts=value.split('/');
     return {year:+parts[0],month:+parts[1],day:+parts[2]}
  }

  toModel(date: NgbDateStruct): string // from internal model -> your mode
  {
    return date?date.year+"/"+('0'+date.month).slice(-2)
           +"/"+('0'+date.day).slice(-2):null
  }
}

Yes a injectable class with two functions, one to transform a NgbDate to string and another to transform string to NgbDate. remember that this change your "model"

For CustomDateParserFormatter

@Injectable()
export class CustomDateParserFormatter {
  parse(value: string): NgbDateStruct
  {
    if (!value)
      return null
     let parts=value.split('/');
     return {year:+parts[0],month:+parts[1],day:+parts[2]} as NgbDateStruct

  }
  format(date: NgbDateStruct): string
  {
    return date?date.year+"/"+('0'+date.month).slice(-2)+"/"+('0'+date.day).slice(-2):null
  }
}

Again an injectable class with two functions, one to transform a NgbDate to string and another to transform string to NgbDate. Remember that this change the "format" of the date -useful if you want, e.g. dd/MM/yyyy-

Then just add as providers in your component

  providers: [{provide: NgbDateAdapter, useClass: CustomDateAdapter},
              {provide: NgbDateParserFormatter, useClass: CustomDateParserFormatter}]

In the stackblitz see the definition of component, you can choose, e.g.

@Component({
  selector: 'ngbd-datepicker-adapter',
  templateUrl: './datepicker-adapter.html',
  providers: [{provide: NgbDateAdapter, useClass: NgbDateNativeAdapter}]
})

or

@Component({
  selector: 'ngbd-datepicker-adapter',
  templateUrl: './datepicker-adapter.html',
  providers: [{provide: NgbDateAdapter, useClass: CustomDateAdapter},
          {provide: NgbDateParserFormatter, useClass: CustomDateParserFormatter}]
})

even you can write

@Component({
  selector: 'ngbd-datepicker-adapter',
  templateUrl: './datepicker-adapter.html',
  providers: [{provide: NgbDateParserFormatter, useClass: CustomDateParserFormatter}]
})

To manteinance the objects like {year,month,day}, but change the "mask" -and the way you input the date

NOTE: You can add the providers to the module too

Answer 2

What you need is

var date = object.year + '/' + object.month + '/'+ object.day