Windows應用商店中的應用程序的日期選擇器空日期

Question

我需要的日期選擇器窗口商店應用，Windows 8中，但我無法找到任何控制，所以我用這個：

jasonmitchell/WinRT中，XAML的DatePicker的

https://github.com/jasonmitchell/WinRT-XAML-DatePicker/blob/master/Samples/WinRTDatePicker.Samples.sln

但我的問題是，默認情況下它顯示今天的日期，我不想，我不想表現出任何日期，如果用戶如果有人沒有申請任何日期

有想法工作在Windows metro應用程序與日期選擇器，這將是偉大的，

我知道Windows 8.1有控制，但我不能移動到Windows 8.1現在！

代碼示例：

<WinRTDatePicker:DatePicker IsEnabled="True" x:Name="dtActualFinishDate" Width="370"/> 

    i want to set value if 

    if (Booking.ActualToDteTme.HasValue) 
       { 
        dtActualFinishDate.SelectedDate = Booking.ActualToDteTme.Value; 
    } 

所以如果ActualToDteTme有任何價值，我想以其他方式申請，我需要保持日期選擇器是空白，

現在它是顯示爲當期的日期，當我點擊更新時，它更新當前日期！這是不正確的行爲！

感謝

Answer 1

我給你更新DatePicker & SelectedDateChangedEventArgs類。在Github上使用這些類。我添加了默認的「月」，「日期」，「年」佔位符文本。如果有人選擇佔位符文本，則默認值爲空&則它也將爲空。

using System; 
using System.Collections.ObjectModel; 
using Windows.UI.Xaml; 
using Windows.UI.Xaml.Controls; 
using Windows.UI.Xaml.Data; 

namespace WinRTDatePicker 
{ 
    [TemplatePart(Name = "_DayOptions", Type = typeof(ComboBox))] 
    [TemplatePart(Name = "_MonthOptions", Type = typeof(ComboBox))] 
    [TemplatePart(Name = "_YearOptions", Type = typeof(ComboBox))] 
    public sealed class DatePicker : Control 
    { 
     public static readonly DependencyProperty SelectedDateProperty = DependencyProperty.Register("SelectedDate", typeof(DateTime?), typeof(DatePicker), new PropertyMetadata(default(DateTime?), SelectedDateChangedCallback)); 
     public static readonly DependencyProperty DayOptionFormatProperty = DependencyProperty.Register("DayOptionFormat", typeof(string), typeof(DatePicker), new PropertyMetadata(default(string))); 
     public static readonly DependencyProperty MonthOptionFormatProperty = DependencyProperty.Register("MonthOptionFormat", typeof(string), typeof(DatePicker), new PropertyMetadata(default(string))); 

     public event EventHandler<SelectedDateChangedEventArgs> SelectedDateChanged; 

     private readonly ObservableCollection<string> daysInRange = new ObservableCollection<string>(); 
     private readonly ObservableCollection<string> monthsInRange = new ObservableCollection<string>(); 
     private readonly ObservableCollection<string> yearsInRange = new ObservableCollection<string>(); 

     public DatePicker() 
     { 
      DefaultStyleKey = typeof(DatePicker); 

      //SelectedDate = DateTime.Today; 
      DayOptionFormat = "dd dddd"; 
      MonthOptionFormat = "MMMM"; 
     } 

     protected override void OnApplyTemplate() 
     { 
      base.OnApplyTemplate(); 

      monthsInRange.Clear(); 
      monthsInRange.Add("Month"); 
      for (int i = 1; i <= 12; i++) 
      { 
       DateTime monthStart = new DateTime(DateTime.Now.Year, i, 1); 
       monthsInRange.Add(monthStart.ToString(MonthOptionFormat)); 
      } 

      CreateBindings(); 
      SetSelectedDate(SelectedDate); 

      DayOptions.SelectionChanged += DayOptionsOnSelectionChanged; 
      MonthOptions.SelectionChanged += MonthOptionsOnSelectionChanged; 
      YearOptions.SelectionChanged += YearOptionsOnSelectionChanged; 
     } 

     private void SetSelectedDate(DateTime? newSelectedDate) 
     { 
      if (DayOptions != null && MonthOptions != null && YearOptions != null) 
      { 
       var TempNewSelectedDate = newSelectedDate; 
       if (newSelectedDate == null) 
       { 
        newSelectedDate = DateTime.Today; 
       } 
       daysInRange.Clear(); 
       yearsInRange.Clear(); 

       daysInRange.Add("Date"); 
       for (int i = 1; i <= DateTime.DaysInMonth(newSelectedDate.Value.Year, newSelectedDate.Value.Month); i++) 
       { 
        DateTime date = new DateTime(newSelectedDate.Value.Year, newSelectedDate.Value.Month, i); 
        daysInRange.Add(date.ToString(DayOptionFormat)); 
       } 

       int minYear = newSelectedDate.Value.Year - 10; 
       int maxYear = newSelectedDate.Value.Year + 10; 

       yearsInRange.Add("Year"); 
       for (int i = minYear; i <= maxYear; i++) 
       { 
        yearsInRange.Add(i.ToString()); 
       } 

       if (TempNewSelectedDate != null) 
       { 
        DayOptions.SelectedIndex = newSelectedDate.Value.Day; 
        MonthOptions.SelectedIndex = newSelectedDate.Value.Month; 
        YearOptions.SelectedItem = newSelectedDate.Value.Year.ToString(); 
       } 

       else 
       { 
        DayOptions.SelectedIndex = 0; 
        MonthOptions.SelectedIndex = 0; 
        YearOptions.SelectedIndex = 0; 
       } 
      } 
     } 

     private void CreateBindings() 
     { 
      Binding dayOptionsBinding = new Binding { Source = daysInRange, Mode = BindingMode.OneWay }; 
      DayOptions.SetBinding(ItemsControl.ItemsSourceProperty, dayOptionsBinding); 

      Binding monthOptionsBinding = new Binding { Source = monthsInRange, Mode = BindingMode.OneWay }; 
      MonthOptions.SetBinding(ItemsControl.ItemsSourceProperty, monthOptionsBinding); 

      Binding yearOptionsBinding = new Binding { Source = yearsInRange, Mode = BindingMode.OneWay }; 
      YearOptions.SetBinding(ItemsControl.ItemsSourceProperty, yearOptionsBinding); 
     } 

     private void UpdateSelectedDateFromInputs() 
     { 
      if (YearOptions.SelectedIndex > 0 && MonthOptions.SelectedIndex > 0 && DayOptions.SelectedIndex > 0) 
      { 
       int year = int.Parse(YearOptions.SelectedValue.ToString()); 
       int month = MonthOptions.SelectedIndex; 
       int day = DayOptions.SelectedIndex; 

       int maxDaysInMonth = DateTime.DaysInMonth(year, month); 
       if (day > maxDaysInMonth) 
       { 
        day = maxDaysInMonth; 
        DayOptions.SelectedIndex = maxDaysInMonth - 1; 
       } 

       if (month == 0) 
        month = 1; 

       if (day == 0) 
        day = 1; 

       SelectedDate = new DateTime(year, month, day); 
      } 
      else if (YearOptions.SelectedIndex == 0 && MonthOptions.SelectedIndex == 0 && DayOptions.SelectedIndex == 0) 
      { 
       SelectedDate = null; 
      } 
     } 

     private void UpdateDayOptions() 
     { 
      if (SelectedDate != null) 
      { 
       int selectedDayIndex = DayOptions.SelectedIndex; 
       int month = MonthOptions.SelectedIndex; 

       if (month != 0) 
       { 
        daysInRange.Clear(); 
        daysInRange.Add("Date"); 
        for (int i = 1; i <= DateTime.DaysInMonth(SelectedDate.Value.Year, month); i++) 
        { 
         DateTime date = new DateTime(SelectedDate.Value.Year, month, i); 
         daysInRange.Add(date.ToString(DayOptionFormat)); 
        } 

        DayOptions.SelectedIndex = selectedDayIndex; 
       } 
      } 
     } 

     private void DayOptionsOnSelectionChanged(object sender, SelectionChangedEventArgs selectionChangedEventArgs) 
     { 
      UpdateSelectedDateFromInputs(); 
     } 

     private void MonthOptionsOnSelectionChanged(object sender, SelectionChangedEventArgs selectionChangedEventArgs) 
     { 
      UpdateSelectedDateFromInputs(); 
      UpdateDayOptions(); 
     } 

     private void YearOptionsOnSelectionChanged(object sender, SelectionChangedEventArgs selectionChangedEventArgs) 
     { 
      UpdateSelectedDateFromInputs(); 
      UpdateDayOptions(); 
     } 

     private static void SelectedDateChangedCallback(DependencyObject obj, DependencyPropertyChangedEventArgs args) 
     { 
      DateTime oldValue = args.OldValue != null ? (DateTime)args.OldValue : DateTime.Today.AddDays(-1); 
      DateTime? newValue = (DateTime?)args.NewValue; 

      if (newValue != oldValue) 
      { 
       DatePicker datePicker = (DatePicker)obj; 
       datePicker.SetSelectedDate(newValue); 

       if (datePicker.SelectedDateChanged != null) 
        datePicker.SelectedDateChanged(datePicker, new SelectedDateChangedEventArgs(newValue)); 
      } 
     } 

     public DateTime? SelectedDate 
     { 
      get { return (DateTime?)GetValue(SelectedDateProperty); } 
      set { SetValue(SelectedDateProperty, value); } 
     } 

     public string DayOptionFormat 
     { 
      get { return (string)GetValue(DayOptionFormatProperty); } 
      set { SetValue(DayOptionFormatProperty, value); } 
     } 

     public string MonthOptionFormat 
     { 
      get { return (string)GetValue(MonthOptionFormatProperty); } 
      set { SetValue(MonthOptionFormatProperty, value); } 
     } 

     private ComboBox DayOptions 
     { 
      get { return (ComboBox)GetTemplateChild("_DayOptions"); } 
     } 

     private ComboBox MonthOptions 
     { 
      get { return (ComboBox)GetTemplateChild("_MonthOptions"); } 
     } 

     private ComboBox YearOptions 
     { 
      get { return (ComboBox)GetTemplateChild("_YearOptions"); } 
     } 
    } 
} 

using System; 

namespace WinRTDatePicker 
{ 
    public class SelectedDateChangedEventArgs : EventArgs 
    { 
     private readonly DateTime? newDate; 

     public SelectedDateChangedEventArgs(DateTime? newDate) 
     { 
      this.newDate = newDate; 
     } 

     public DateTime? NewDate 
     { 
      get { return newDate; } 
     } 
    } 
} 

Answer 2

對於綁定工作，你應該改變SelectedDateProperty到

public static readonly DependencyProperty SelectedDateProperty = 
    DependencyProperty.Register("SelectedDate", 
           typeof(object), 
           typeof(NullableDatePicker), 
           new PropertyMetadata(null, SelectedDateChangedCallback)); 

，以避免錯誤：

Error: Converter failed to convert value of type 'System.DateTime, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' to type 'Nullable`1';