如何在WPF应用程序中更改DateTimePicker的格式（例如dd/MMM/yyyy）

Question

我想在WPF应用程序中更改DateTimePicker选择的日期格式

- Rajendra

Answer 1

最近我在处理这个问题。我找到了一种简单的方法来执行此自定义格式，我希望这能帮到你。首先，您需要在XAML中为当前的DatePicker应用特定的样式，就像这样：

<DatePicker.Resources>
    <Style TargetType="{x:Type DatePickerTextBox}">
        <Setter Property="Control.Template">
            <Setter.Value>
                <ControlTemplate>
                    <TextBox x:Name="PART_TextBox" Width="113" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" Text="{Binding Path=SelectedDate,Converter={StaticResource DateTimeFormatter},RelativeSource={RelativeSource AncestorType={x:Type DatePicker}},ConverterParameter=dd-MMM-yyyy}" BorderBrush="{DynamicResource BaseBorderBrush}" />
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</DatePicker.Resources>

在这一部分中，您可以注意到存在一个名为DateTimeFormatter的转换器，用于将绑定到“PART_TextBox”的Text属性。该转换器接收包含自定义格式的转换器参数。最后，我们添加了C＃中的DateTimeFormatter转换器代码。

public class DateTimeConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        DateTime? selectedDate = value as DateTime?;

        if (selectedDate != null)
        {
            string dateTimeFormat = parameter as string;
            return selectedDate.Value.ToString(dateTimeFormat);
        }

        return "Select Date";
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        try
        {

            var valor = value as string;
            if (!string.IsNullOrEmpty(valor))
            {
                var retorno = DateTime.Parse(valor);
                return retorno;
            }

            return null;
        }
        catch
        {
            return DependencyProperty.UnsetValue;
        }
    }
}

我希望这对你有所帮助。如果有任何问题或建议改进，请告诉我。

- Fernando García

Answer 2

Thread.CurrentThread.CurrentCulture = (CultureInfo)Thread.CurrentThread.CurrentCulture.Clone();
Thread.CurrentThread.CurrentCulture.DateTimeFormat.ShortDatePattern = "dd-MMM-yyyy";      

- Legish

---

这是在UI控件中更改，但在视图模型属性中没有更改。我得到的计算机日期格式相同。有什么想法吗？ - J R B

这正是我所需要的。谢谢！ - BlueDev

Answer 3

将以下样式添加到您的XAML或App.xaml文件中

 <Style TargetType="{x:Type DatePickerTextBox}">
     <Setter Property="VerticalContentAlignment" Value="Center"/>
     <Setter Property="Control.Template">
         <Setter.Value>
             <ControlTemplate>
                 <TextBox x:Name="PART_TextBox"
            Text="{Binding Path=SelectedDate, StringFormat='dd.MM.yyyy', 
            RelativeSource={RelativeSource AncestorType={x:Type DatePicker}}}" />
             </ControlTemplate>
         </Setter.Value>
     </Setter>
 </Style>

- Hallgeir Engen

Answer 4

在XAML中：

<toolkit:DatePicker SelectedDateFormat="Long" />

或者

<toolkit:DatePicker SelectedDateFormat="Short" />

- Stuart

---

+1 我想知道在XAML中是否有一种方法可以提供自定义日期时间格式字符串。 - Doguhan Uluca

在原始问题中，DatePickerTextBox控件不可用此属性。 - Wouter

Answer 5

感谢@Fernando García提供的基础。

我为DatePicker编写了一个DateFormat附加属性，让您可以提供一个格式字符串来显示和输入日期。

对于输入，它将尝试使用提供的格式进行解析，如果失败，则尝试使用当前文化的格式进行解析。

以下是使用此格式的示例：

<DatePicker my:DatePickerDateFormat.DateFormat="dd/MMM/yyyy"/>

DateFormat附加属性是指：

public class DatePickerDateFormat
{
    public static readonly DependencyProperty DateFormatProperty =
        DependencyProperty.RegisterAttached("DateFormat", typeof (string), typeof (DatePickerDateFormat),
                                            new PropertyMetadata(OnDateFormatChanged));

    public static string GetDateFormat(DependencyObject dobj)
    {
        return (string) dobj.GetValue(DateFormatProperty);
    }

    public static void SetDateFormat(DependencyObject dobj, string value)
    {
        dobj.SetValue(DateFormatProperty, value);
    }

    private static void OnDateFormatChanged(DependencyObject dobj, DependencyPropertyChangedEventArgs e)
    {
        var datePicker = (DatePicker) dobj;

        Application.Current.Dispatcher.BeginInvoke(
            DispatcherPriority.Loaded, new Action<DatePicker>(ApplyDateFormat), datePicker);
    }

    private static void ApplyDateFormat(DatePicker datePicker)
    {
        var binding = new Binding("SelectedDate")
            {
                RelativeSource = new RelativeSource {AncestorType = typeof (DatePicker)},
                Converter = new DatePickerDateTimeConverter(),
                ConverterParameter = new Tuple<DatePicker, string>(datePicker, GetDateFormat(datePicker))
            };
        var textBox = GetTemplateTextBox(datePicker);
        textBox.SetBinding(TextBox.TextProperty, binding);

        textBox.PreviewKeyDown -= TextBoxOnPreviewKeyDown;
        textBox.PreviewKeyDown += TextBoxOnPreviewKeyDown;

        datePicker.CalendarOpened -= DatePickerOnCalendarOpened;
        datePicker.CalendarOpened += DatePickerOnCalendarOpened;
    }

    private static TextBox GetTemplateTextBox(Control control)
    {
        control.ApplyTemplate();
        return (TextBox) control.Template.FindName("PART_TextBox", control);
    }

    private static void TextBoxOnPreviewKeyDown(object sender, KeyEventArgs e)
    {
        if (e.Key != Key.Return)
            return;

        /* DatePicker subscribes to its TextBox's KeyDown event to set its SelectedDate if Key.Return was
         * pressed. When this happens its text will be the result of its internal date parsing until it
         * loses focus or another date is selected. A workaround is to stop the KeyDown event bubbling up
         * and handling setting the DatePicker.SelectedDate. */

        e.Handled = true;

        var textBox = (TextBox) sender;
        var datePicker = (DatePicker) textBox.TemplatedParent;
        var dateStr = textBox.Text;
        var formatStr = GetDateFormat(datePicker);
        datePicker.SelectedDate = DatePickerDateTimeConverter.StringToDateTime(datePicker, formatStr, dateStr);
    }

    private static void DatePickerOnCalendarOpened(object sender, RoutedEventArgs e)
    {
        /* When DatePicker's TextBox is not focused and its Calendar is opened by clicking its calendar button
         * its text will be the result of its internal date parsing until its TextBox is focused and another
         * date is selected. A workaround is to set this string when it is opened. */

        var datePicker = (DatePicker) sender;
        var textBox = GetTemplateTextBox(datePicker);
        var formatStr = GetDateFormat(datePicker);
        textBox.Text = DatePickerDateTimeConverter.DateTimeToString(formatStr, datePicker.SelectedDate);
    }

    private class DatePickerDateTimeConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            var formatStr = ((Tuple<DatePicker, string>) parameter).Item2;
            var selectedDate = (DateTime?) value;
            return DateTimeToString(formatStr, selectedDate);
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            var tupleParam = ((Tuple<DatePicker, string>) parameter);
            var dateStr = (string) value;
            return StringToDateTime(tupleParam.Item1, tupleParam.Item2, dateStr);
        }

        public static string DateTimeToString(string formatStr, DateTime? selectedDate)
        {
            return selectedDate.HasValue ? selectedDate.Value.ToString(formatStr) : null;
        }

        public static DateTime? StringToDateTime(DatePicker datePicker, string formatStr, string dateStr)
        {
            DateTime date;
            var canParse = DateTime.TryParseExact(dateStr, formatStr, CultureInfo.CurrentCulture,
                                                  DateTimeStyles.None, out date);

            if (!canParse)
                canParse = DateTime.TryParse(dateStr, CultureInfo.CurrentCulture, DateTimeStyles.None, out date);

            return canParse ? date : datePicker.SelectedDate;
        }
    }
}

- Simon Brydon

---

我尝试使用上述提到的类来获取正确的日期格式。乍一看，我以为它按预期工作。但是过了一会儿，我发现当我选择一个日期时，我得到了正确的格式，例如dd.MM.yyyy。然后，当我将焦点移动到其他控件时，我发现日期再次转换为默认格式，即MM.dd.yyyy。从这个观察中，我发现DateSeparator保持不变，但是DatePicker失去焦点后日期的格式会改变。 - Vishal

Answer 6

DatePicker1.SelectedDate = DatePicker1.SelectedDate.Value.ToString("dd/MM/yyyy")

- Dee

---

这个能编译吗？ - code4life

Answer 7

对我而言，为了改变DatePicker格式（例如Thread.CurrentCulture），改变环境并不是一个好主意。 当然，你可以创建从DatePicker派生的Control，并实现像Format这样的依赖属性，但这需要太多的努力。

我发现的简单而优雅的解决方案是将值绑定到某个未使用的属性（我使用ToolTip属性），并在更改SelectedDate时更新此属性。

一种单向绑定的C#实现如下：

    DatePicker datePicker = new DatePicker();
    datePicker.SetBinding(ToolTipProperty, "Date");
    datePicker.SelectedDateChanged += (s, ea) =>
        {
            DateTime? date = datePicker.SelectedDate;
            string value = date != null ? date.Value.ToString("yyyy-MM-dd") : null;
            datePicker.ToolTip = value;
        };

XAML+C# 应该长这样：

XAML：

<DatePicker ToolTip="{Binding Date Mode=TwoWay}"
            SelectedDateChanged="DatePicker_SelectedDateChanged"/>

C#：

private void DatePicker_SelectedDateChanged(object sender, EventArgs ea)
{
    DatePicker datePicker = (DatePicker)sender;
    DateTime? date = datePicker.SelectedDate;
    string value = date != null ? date.Value.ToString("yyyy-MM-dd") : null;
    datePicker.ToolTip = value;
}

对于双向实现，处理ToolTipChanged事件的方式相同，以更新SelectedDate。

- Vitaliy Ulantikov

Answer 8

试一下

    private void UserControl_Loaded(object sender, RoutedEventArgs e)
    {
      DateLabel.Content = Convert.ToDateTime(datePicker1.Text).ToString("dd-MM-yyyy");
    }

- Shelly

Answer 9

通常日期时间格式存储在资源文件中，因为这有助于应用的国际化。

您可以从资源文件中获取格式并使用ToString(DATE_FORMAT)。

在您的情况下，您可能想要使用

。

dateTimePicker.SelectedDate.ToString("dd-MMM-yyyy");

- AB Kolan