public void signUpUserToMeeting(string login, string name) { var meeting = this.getMeetingsByName(name); if (meeting == null || meeting.NumberOfFreePlaces == 0) { return; } var user = this.getUserByLogin(login); if (user == null) { return; } var participation = participationFactory.create(login, name); participationRepository.addParticipations(participation); meetingsRepository.decreaseNumberOfFreePlaces(meeting); }