public IHttpActionResult PostEnroll([FromBody] CoursesOfStudent cos)
{
string Name = Thread.CurrentPrincipal.Identity.Name;
int subid = cos.CourseId;
Subject ss = subRepo.GetSubDetaileById(subid);
ss.StudentCount += 1;
subRepo.Edit(ss);
cos.TeacherId = ss.TeacherId;
cosRepo.Insert(cos);
Registration reg = new Registration();
reg.SubjectId = cos.CourseId;
reg.StudentName = Name;
reg.Fee = ss.Price;
regRepo.Insert(reg);
return(Ok(cos));
}