Is it correct to implement a custom NgbDateParserFormatter to change the format of the input value on NgbInputDatepicker?

Question

I'm using the datepicker (ng-boostrap) in a popup and I would like to change the date format to dd-mm-yyyy.

It seems that it can be solved by implementing a new NgbDateParserFormatter to replace the default NgbDateISOParserFormatter.

But I was wondering if there is another way.

UPDATE:

A small implementation of NgbDateParserFormatter using Moment.js (tested with version 1.0.0-alpha.14 of ng-bootstrap):

import {NgbDateParserFormatter, NgbDateStruct} from '@ng-bootstrap/ng-bootstrap';
import * as moment from 'moment';

export class NgbDateMomentParserFormatter extends NgbDateParserFormatter {
    constructor(private momentFormat: string) {
        super();
    };
    format(date: NgbDateStruct): string {
        if (date === null) {
            return '';
        }
        let d = moment({ year: date.year, 
                         month: date.month - 1, 
                         date: date.day });
        return d.isValid() ? d.format(this.momentFormat) : '';
    }

    parse(value: string): NgbDateStruct {
        if (!value) {
            return null;
        }
        let d = moment(value, this.momentFormat);
        return d.isValid() ? { year: d.year(), 
                               month: d.month() + 1, 
                               day: d.date() } : null;
    }
}

And in a module, you include the provider using a factory to indicate the date format as a parameter:

---

@NgModule({

  ---

  providers: [
    { 
      provide: NgbDateParserFormatter, 
      useFactory: () => { return new NgbDateMomentParserFormatter("DD-MM-YYYY") } 
    }
  ]

  ---

})

Answer 1

As of today implementing a custom NgbDateParserFormatter is the best way to go. So yes, it is a correct way.

In the future we might have a more sophisticated implementation of the NgbDateParserFormatter where you will be able to just pass a desired format (ex. yyyy-MM-dd). Adding this feature will depend on user's interest.

You might also check some more background info in https://github.com/ng-bootstrap/ng-bootstrap/issues/754#issuecomment-247767027