public GradeValuesResult editGradeValue(int gradeId, int registrationId, string value, byte[] currentTimeStamp)
        {
            using (var db = new NTR2013Entities())
            {
                var original = db.GradeValues.Where(g => g.GradeID == gradeId && g.RegistrationID == registrationId).ToList().ElementAt(0);

                if (!compareTimeStamp(original.TimeStamp, currentTimeStamp))
                {
                    GradeValuesResult result = new GradeValuesResult(ErrorMessage.REMOVE_GRADES_CONCURRENCY);
                    GradeValues       grade  = new GradeValues {
                        GradeValueID = original.GradeValueID, GradeID = original.GradeID, RegistrationID = original.RegistrationID, Date = original.Date, Value = original.Value, TimeStamp = original.TimeStamp, Grades = null, Registrations = null
                    };
                    result.data = grade;
                    return(result);
                }

                //db.GradeValues.Remove(original);
                original.Value = value;
                db.SaveChanges();

                GradeValues current = new GradeValues {
                    GradeValueID = original.GradeValueID, GradeID = original.GradeID, RegistrationID = original.RegistrationID, Date = original.Date, Value = original.Value, TimeStamp = original.TimeStamp, Grades = null, Registrations = null
                };
                return(new GradeValuesResult(current));
            }
        }
        public GradeValuesResult editGradeValue(int gradeId, int registrationId, string value, byte[] currentTimeStamp)
        {
            using (var db = new NTR2013Entities())
            {
                var original = db.GradeValues.Where(g => g.GradeID == gradeId && g.RegistrationID == registrationId).ToList().ElementAt(0);

                if (!compareTimeStamp(original.TimeStamp, currentTimeStamp))
                {
                    GradeValuesResult result = new GradeValuesResult(ErrorMessage.REMOVE_GRADES_CONCURRENCY);
                    GradeValues grade = new GradeValues { GradeValueID = original.GradeValueID, GradeID = original.GradeID, RegistrationID = original.RegistrationID, Date = original.Date, Value = original.Value, TimeStamp = original.TimeStamp, Grades = null, Registrations = null };
                    result.data = grade;
                    return result;
                }

                //db.GradeValues.Remove(original);
                original.Value = value;
                db.SaveChanges();

                GradeValues current = new GradeValues { GradeValueID = original.GradeValueID, GradeID = original.GradeID, RegistrationID = original.RegistrationID, Date = original.Date, Value = original.Value, TimeStamp = original.TimeStamp, Grades = null, Registrations = null };
                return new GradeValuesResult(current);
            }
        }