GFlow - Specific User Assignment

functions.php

<?php
add_filter( "gravityflow_user_field", "gflow_request_manager", 10, 3 );

function gflow_request_manager( $choices, $form_id, $field ) {
	if ( $form_id == 1 && $field->id == 15 ) {
		$manager = get_user_by('email', get_user_meta(get_current_user_id(), "manager_email", true) );

		if( false !== $manager ) {
			$choices = array(
				array('value' => $manager->ID, 'text' => $manager->first_name . ' ' . $manager->last_name)
			);
		} else {
			$choices = array(
				array('value' => 'ERROR', 'text' => 'ERROR')
			);
		}

	}
	return $choices;
}

?>