可空对象必须具有使用C＃错误的值datetime [英] Nullable object must have a value datetime using c# error

问题描述

我在c＃datetime中遇到一个问题，我尝试了不止时间。不是
提供问题解决方案。因此，请给我一个解决方案。

I am facing one problem in c# datetime i have trying more than time. it's not giving a problem solution. so give me one solution.

var accommodationcategoryList = EmployeeAttendanceCacheMaster.GetAllEmployeeAttendance();
DataSourceResult result = accommodationcategoryList.ToDataSourceResult(request);

foreach(var item in accommodationcategoryList)
{
    item.User = UserCacheMaster.GetUserById(item.employeeid);
    item.loginTime = item.login.Value.ToShortDateString();
    item.logoutTime = (item.logout.Value.ToShortDateString() != null) ? item.logout.Value.ToShortDateString() : "-";
}

我的问题没有显示登出时间，它显示错误看起来像是

My problem is not showing the logouttime it showing error looks like

可空对象必须具有值

nullable object must have a value

推荐答案

您正在尝试检查针对null对象的转换是否为null，而不是检查可为null的对象本身。您需要更改以下行：

You're trying to check if a conversion against the null object is null rather than checking the nullable object itself. You need to change this line:

item.logoutTime = (item.logout.Value.ToShortDateString() != null) ? item.logout.Value.ToShortDateString() : "-";

到

item.logoutTime = item.logout.HasValue ? item.logout.Value.ToShortDateString() : "-";

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