private void ProcessPostBack()
{
var eventStartTime = DateTime.Parse(this.Request.Form["EventTime"], null, DateTimeStyles.RoundtripKind);
var patientId = Guid.Parse(this.Request.Form["PatientId"]);
var physicianId = Guid.Parse(this.Request.Form["PhysicianId"]);
_appointmentsBll.CreateAppointment(eventStartTime, patientId, physicianId);
this.CurrentUnitOfWork().DbContext.SaveChanges();
Response.Redirect(Page.ResolveUrl("~/RequestAppointment.aspx"));
}