Special field shortcode

The field is not added to the database because the plugin doesn’t know what the shortcode does.

The next step is to append the new date to the other fields:

/**
 * Add datepicker field to new testimonial post meta fields.
 * 
 * @param $new_meta array
 *
 * @return array
 */
function custom_datepicker_add_meta( $new_meta ) {
  if ( isset( $_POST['datepicker1'] ) && $_POST['datepicker1'] ) {
    $new_meta['datepicker1'] = $_POST['datepicker1'];
  }
  return $new_meta;
}
add_filter( 'wpmtst_new_testimonial_meta', 'custom_datepicker_add_meta' );

You will need another shortcode to retrieve and display the date.

A simpler approach would be to use a plain text field and attach the datepicker to that.

function my_datepicker( $atts ) {
  wp_enqueue_script( 'jquery-ui-datepicker' );
  ?>
  <script>
    jQuery(function () {
      // use your date field's id
      jQuery('#wpmtst_newdate').datepicker({})
    })
  </script>
  <?php
}
add_action( 'wpmtst_form_rendered', 'my_datepicker' );

That will make the date field available in the post meta box and the view editor so you can display it like any other field.

Let’s take a step back.

If you want to add a date field, you don’t need to use a shortcode field.

Instead, try this. Add a plain text field and attach datepicker to it using the second function above. That would go in your theme’s functions.php or an mu-plugin. Change “newdate” to your field name.

Then the date field will be available everywhere with the rest of the fields.

Does that make sense?