解决Nullable对象的最佳方法必须在datetime中有一个值

Question

I have a function that get the datetime value and it converts the datetime to a string as you can see here :

 public string ConvertToPersianToShow(DateTime? datetime)
        {
            if (datetime.HasValue)
            {
                PersianCalendar persian_date = new PersianCalendar();
                string date;
                string year = Convert.ToString(persian_date.GetYear(datetime.Value));
                string Month = Convert.ToString(persian_date.GetMonth(datetime.Value));
                string day = Convert.ToString(persian_date.GetDayOfMonth(datetime.Value));

                date = year + "/" + Month + "/" + day;
                return date;
            }
            else
            {
                return
                    "ثبت نشده";
            }
        }

as you can see here the ConvertToPersianToShow accepts an argument and the argument can be null so

 string startdate = callenderRepository.ConvertToPersianToShow(item.StartDate.Value);

sometimes this value can be null item.StartDate.Value so and i got this error :

Nullable object must have a value.

so i have to check item.StartDate.hasvalue in the first line of my code to prevent the error.

is there any best method that i can use that?

Best regards

Answer 1

由于您的ConvertToPersianToShow接受可为空的DateTime并检查其是否具有值，因此您可以使用可为空的对象本身而不是其基础值来调用它：

string startdate = callenderRepository.ConvertToPersianToShow(item.StartDate);

Answer 2

Sometimes item.StartDate is null and you try to get its value by item.StartDate.Value . use this:

string startdate = callenderRepository.ConvertToPersianToShow(item.StartDate);