如何访问查询变量的每个元素

Question

我是 C# 和 WPF 的新手。假设我有一张桌子。该表有两个字段：“firstName”和“birthDate”。我写了一个查询来获取“生日”记录，然后我想在数据网格上显示它。但在此之前，我想用一个函数将“公历日期”更改为“jalali 日期”。

在 C# 中：

var searchQueryOfDateAndTime = (from b in FaceDB.tblCameras
                                        join c in FaceDB.tblTraffics
                                       on b.Camera_Id equals c.Camera_Id
                                       join a in FaceDB.tblknownPeoples
                                       on c.IdNumber equals a.IdNumber

                                       where
                                       (
                                           string.Compare(c.EntryDate.ToString(), miladiFromDate.ToString()) >= 0
                                           &&
                                           string.Compare(c.EntryDate.ToString(), miladiToDate.ToString()) <= 0
                                       )
                                       where
                                       (
                                           string.IsNullOrEmpty(timFromHour.Text.ToString())
                                           ||
                                           string.Compare(c.EntryTime.ToString(), timFromHour.Text.ToString()) >= 0
                                           &&
                                           string.IsNullOrEmpty(timToHour.Text.ToString())
                                           ||
                                           string.Compare(c.ExitTime.ToString(), timToHour.Text.ToString()) <= 0
                                       )

                                       select new { a.Name, a.Family, EntryDate = Georgian2Jalali(c.EntryDate), c.EntryTime, a.Occupation, ExitDate = Georgian2Jalali(c.ExitDate), c.ExitTime, b.Camera_Name, c.PicAddress, a.FirstPicAddress, c.IdNumber, c.Camera_Id }).ToList();

        dgvFinalyReport.ItemsSource = searchQueryOfDateAndTime;

在 WPF 中：

<DataGrid x:Name="dgvFinalyReport" Height="431" Width="630" Canvas.Left="273" Canvas.Top="10" AutoGenerateColumns="False" CanUserDeleteRows="False">
                    <DataGrid.Columns>
                        <DataGridTextColumn Header="firstname" Binding="{Binding Name}" Width="78" />
                        <DataGridTextColumn Header="Last name" Binding="{Binding Family}" Width="78" />
                        <DataGridTextColumn Header="Entry date" Binding="{Binding EntryDate}" Width="78" />
                        <DataGridTextColumn Header="entry time" Binding="{Binding EntryTime}" Width="78" />
                        <DataGridTextColumn Header="exit date" Binding="{Binding ExitDate}" Width="78" />
                        <DataGridTextColumn Header="exit time" Binding="{Binding ExitTime}" Width="78" />
                        <DataGridTextColumn Header="occupation" Binding="{Binding Occupation}" Width="78" />
                        <DataGridTextColumn Header="Cam_Name" Binding="{Binding Camera_Name}" Width="78" />
                        <DataGridTextColumn Header="getface" Binding="{Binding PicAddress}" Width="78" />
                        <DataGridTextColumn Header="first face" Binding="{Binding FirstPicAddress}" Width="78" />
                    </DataGrid.Columns>
                </DataGrid>

Answer 1

另一种选择是创建一个转换器，该转换器采用公历日期并将其转换为 Jalali 日期：

public class JalaliDateConverter : IValueConverter
{
    public Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
       // Gregorian to Jalali conversion code

       return jalaliaDate;
    }

    public ConvertBack((object value, Type targetType, object parameter, CultureInfo culture)
    {
        // Jalali to Gregorian conversion code

        return gregorianDate;
    }
}

然后在你的 XAML 中你有：

<DataGridTextColumn Header="Birth Day"
                    Binding="{Binding birthDate, Converter={StaticResource JalaliDateConverter}}"
                    Width="80" />

请参阅 here 了解有关转换器的更完整教程。

Answer 2

由于new {} 创建了一个只读匿名类型，因此您无法循环查询并更新生日的值。相反，您可以直接更改该值：

var query = from f in mydb.mytbl.AsEnumerable()
select new
{
    f.firstName,
    BirthDate = ConvertToJalali(f.BirthDate)
};

private DateTime ConvertToJalali(DateTime dt)
{
 // your implementation here
}

注意：请注意使用AsEnumerable()，因为它将所有记录从数据库拖到内存中，但在您的特定情况下，它没有任何区别，因为您没有任何 where 子句。