title: How to format Angular Material date-picker inside Formly form for service layer (not display format)
body: <p>I would like to expose my date value as date only (&quot;yyyy-MM-dd&quot;) on an Angular Material date picker. Currently, the default date value is an ISO format (includes time).</p>
  <p>I have a starter <a href="https://stackblitz.com/edit/angular-formly-material-datepicker-accessor-4pbh2f?file=src/app/app.component.html" rel="nofollow noreferrer">Stackblitz</a> project with the the required setup. The <code>formly-datepicker.type</code> is where I would like to centralize the conversion so that any date used in the model will be formatted properly for the service layer.</p>
  <p>One of my attempts to accomplish it in a centralized manner is using the Angular ControlValueAccessor, but the value is never updated. <a href="https://stackblitz.com/edit/angular-formly-material-datepicker-accessor-attempt1-xe86yc?file=src/assets/json-schema/date.json" rel="nofollow noreferrer">ControlValueAccessor Stackblitz</a></p>
  <p>In the example Stackblitz, after changing the date and clicking <em>Submit</em> the value I need returned would be something like: <code>{&quot;mydate&quot;:&quot;1940-03-11&quot;}</code>(without the time information).</p>