How to dynamically change Datepicker date time format?

Question

Since the format for @danielmoncada/angular-datetime-picker datepicker is being provided via Angular DI, we need to utilize this approach and dynamically provide the formats.

This is what the dates From and To look like now:

This is what I wanted to achieve: when we have month view selected - we dynamically change the datepicker formats to the desired:

Answer 1

First we need to create a format provider service, which we will then inject into the datepicker component:

@Injectable()
export class DatepickerFormatsProvider {
  private currentFormats: OwlDateTimeFormats;

  constructor() {
    this.currentFormats = DAYS_VIEW_FORMATS;
  }

  setFormats(formats: OwlDateTimeFormats) {
    this.currentFormats = formats;
  }

  getFormats(): OwlDateTimeFormats {
    return this.currentFormats;
  }
}

Inject in into the component and use useFactory to get the format.

@Component({
  selector: 'datepicker',
  templateUrl: 'datepicker.component.html',
  providers: [
    {
      provide: OWL_DATE_TIME_FORMATS,
      useFactory: (datepickerFormatsProvider: DatepickerFormatsProvider) => datepickerFormatsProvider.getFormats(),
      deps: [DatepickerFormatsProvider],
    },
    DatepickerFormatsProvider
  ]
})
export class DatepickerComponent implements OnInit {

In same component in OnInit Hook you can overwrite the default provided value:

  ngOnInit(): void {
    if (this.selectionMode === 'month') {
      this.datepickerFormatsProvider.setFormats(MONTH_VIEW_FORMATS);
    } else {
      this.datepickerFormatsProvider.setFormats(DAYS_VIEW_FORMATS);
    }
  }

If we need to dynamically change the date-format of the datepicker - it only works in OnInit hook. We need to re-render the component and trigger OnInit E.g. with use of *ngIf and async pipe on datepicker selector in parent component.