public WalkInAppointmentViewModel() { _dialogService = new DialogBoxService(); Timeslot = AppointmentLogic.CalcWalkInTimeslot(); if (IsInDesignMode) { EstimatedTime = "2 Hours 45 Minutes"; } else { if (Timeslot == null) { EstimatedTime = "No Avaliable Time. Try booking a reservation."; } else { EstimatedTime = CalcWaitTime(); } } // When patientID message is received (from PatientDBConverter), set patient ID in VM. MessengerInstance.Register <double>(this, SetPatientID); BookAppointmentCommand = new RelayCommand(BookAppointment); }