public async Task <ActionResult> MedicineCourse(int id)
{
if (id == 0)
{
throw new NullReferenceException("medicine course not found");
}
if (!_context.Medicines.Any())
{
throw new NullReferenceException("medicine no entries");
}
var medicines = await _medicineService.GetByForeignKey(id);
return(Ok(medicines ?? new List <Medicine>()));
}