ion-datetime bind to epoch

I have a model that requires the date/time as milliseconds in Unix Epoch format. I have tried using the Moment interface, Date | numeric as type and I can't seem to get it right.

I want the control to display in human readable format and the picker likewise but I want the databound model to be numeric. I can't use a pipe ("Cannot have a pipe in an action expression"). Should I remove the two way databinding, translate the value in the changeModel function and populate the person.date_of_birth with a similar function?

.html

<ion-datetime displayFormat="MMM DD, YYYY" pickerFormat="MMM DD, YYYY" (ngModelChange)="changeModel($event)" [(ngModel)]="person.date_of_birth"></ion-datetime>

.ts:

let person={name: string, date_of_birth: numeric};

The model is written to a local database on the mobile (pouchdb/sqlite) and then synched with a mongodb database via nodejs REST API. It is only displayed on this one html page so I'd really like it to be numeric everywhere else.

As input for your ion-datetime, you can use public yourDate: string = new Date().toISOString();. So this is the value you want to bind to your ion-datetime.

If you want to have another format, you can do something like this new Date(yourDate).getTime(). If you have this ISOString, you can always parse it back to a Date object.

Update

Working with a pipe and a format function.

Here we have a one-way databinding that is using my custom date pipe, thats formatting an numeric date to an ISOString. The (ngModelChange) event is the "other-way" binding, thats assigning back a numeric value to date_of_birth (format is a custom function).

page.html

<ion-datetime displayFormat="MMM DD, YYYY" 
    (ngModelChange)="date_of_birth=format($event)" 
    [ngModel]="date_of_birth | date"></ion-datetime> 

date.pipe.ts

import { Pipe, PipeTransform } from '@angular/core';

@Pipe({
  name: 'date'
})
export class DatePipe implements PipeTransform {

  transform(value: any, args?: any): any {
    return new Date(value).toISOString();
  }

}

page.ts

date_of_birth: number = new Date().getTime();

format(val) {
  return new Date(val).getTime();
}

Working StackBlitz