可空对象必须有值吗?

Nullable object must have a value?(可空对象必须有值吗?)

问题描述

上线:bool travel = fill.travel.Value; 我收到以下错误:

On the line: bool travel = fill.travel.Value; I am getting the following error:

可空对象必须有值

我不知道为什么.我想要做的就是获取当前为假的旅行数据库中的值.任何帮助，将不胜感激.

and i am not sure why. All I want to do is get the value in the database of travel which is currently false. Any help would be appreciated.

using (var db = new DataClasses1DataContext())
{
    var fill = (from f in db.expenseHdrs
                where f.rptNo == getPkRowReport()
                select f).FirstOrDefault();

    txtReportDesc.Text = fill.description;
    txtPeriod.Text = fill.period;
    txtPurpose.Text = fill.purpose;

    bool travel = fill.travel.Value;
    chkTravel.Checked = travel 
 }

推荐答案

您可以随时切换到

 fill.travel.GetValueOrDefault()

提供默认值 (false) 或数据库中布尔列的值.或者您可以使用重载指定默认值.无论哪种方式，可空对象当前都没有值，这就是您得到该异常的原因.

To provide the default (false), or the value of the boolean column from the database. Or you can specify the default with an overload. Either way, the nullable currently doesnt have a value, which is why you get that exception.

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