public string AddUnit(string unitname, string description, string operateid)
{
var dal = new ProductsDAL();
var id = dal.AddUnit(unitname, description, operateid);
if (!string.IsNullOrEmpty(id))
{
var list = GetUnits();
list.Add(new ProductUnit() { UnitID = id, UnitName = unitname });
}
return id;
}