public IHttpActionResult PostDepartment([FromBody] Department department)
 {
     try
     {
         var Departments = db.Departments.ToList();
         if (Departments == null) //in case that there aren't any students on the db yet
         {
             Departments = new List <Department>();
         }
         if (Departments.Exists(d => d.Id == department.Id)) //validates if the id written it's already on the db
         {
             return(NotFound());                             //return response id it's incorrect
         }
         else
         {
             db.Departments.Add(department);
         }
         db.SaveChanges();
         return(Ok());
     }
     catch
     {
         return(InternalServerError()); //return response when there is an error adding an student
     }
 }