public IHttpActionResult GetAllClass()
 {
     try
     {
         if (ModelState.IsValid)
         {
             return(Content(HttpStatusCode.OK, new DataModel()
             {
                 HttpStatusCode = System.Net.HttpStatusCode.OK,
                 Exception = null,
                 Data = professorService.GetAllClass()
             }));
         }
         else
         {
             return(BadRequest(ModelState));
         }
     }
     catch (Exception ex)
     {
         return(InternalServerError(ex));
     }
 }