class Record {
DateTime dateField
def getAllRecordsForOneDay(aDay = new DateTime()) {
def localDate = new LocalDate(aDay);
Record.findAllDateFieldBetween(localDate.toDateTimeAtStartOfDay(), localDate.plusDays(1).toDateTimeAtStartOfDay())
//Or with criteria
Record.withCriteria {
between 'dateField', localDate.toDateTimeAtStartOfDay(), localDate.plusDays(1).toDateTimeAtStartOfDay()
}
}
}