internal Contractor EditOne(Contractor editContractor)
        {
            Contractor contractor = GetOne(editContractor.Id);

            if (contractor == null)
            {
                throw new SystemException("INVALID ID");
            }
            else
            {
                editContractor.Age    = editContractor.Age != null ? editContractor.Age : contractor.Age;
                editContractor.Name   = editContractor.Name != null ? editContractor.Name : contractor.Name;
                editContractor.Salary = editContractor.Salary != null ? editContractor.Salary : contractor.Salary;
                return(_crepo.EditOne(editContractor));
            }
        }