public function transform($value): ?string
    {
        /** TODO add sanity check is array of Location object? */
        if (!is_array($value) || empty($value)) {
            return null;
        }

        return implode(',', array_column($value, 'id'));
    }
public function transform($value): ?string
    {
        /** TODO add sanity check is array of Location object? */
        if (!is_array($value) || empty($value)) {
            return null;
        }

        return implode(',', array_column($value, 'id'));
    }
public function transform ( $ value ) : ? string { /** TODO add sanity check is array of Location object? */ if ( ! is_array ( $ value ) || empty ( $ value ) ) { return null ; } return implode ( ',' , array_column ( $ value , 'id' ) ) ; }
Transforms a domain specific Location objects into a Location's ID comma separated string.

@param mixed $value

@return string|null
Transforms a domain specific Location objects into a Location s ID comma separated string .