DatePicker.DateValidationError Event

 
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Occurs when Text is set to a value that cannot be interpreted as a date or when the date cannot be selected.

Namespace:   System.Windows.Controls
Assembly:  PresentationFramework (in PresentationFramework.dll)

Public Event DateValidationError As EventHandler(Of DatePickerDateValidationErrorEventArgs)

After the DateValidationError event occurs, if you set the DatePickerDateValidationErrorEventArgs.ThrowException property to true, one of the following exceptions is raised:

Exception type

Condition

FormatException

The text entered cannot be parsed to a valid date, and the exception is not suppressed.

ArgumentOutOfRangeException

The text entered parses to a date that is not selectable.

<DatePicker DateValidationError="eventhandler"/>

The following example creates a DatePicker that displays the dates in August 2009 and specifies that each Saturday and Sunday is not selectable.

Dim datePickerWithBlackoutDates As New DatePicker()

datePickerWithBlackoutDates.DisplayDateStart = New DateTime(2009, 8, 1)
datePickerWithBlackoutDates.DisplayDateEnd = New DateTime(2009, 8, 31)
datePickerWithBlackoutDates.SelectedDate = New DateTime(2009, 8, 10)

datePickerWithBlackoutDates.BlackoutDates.Add( _
    New CalendarDateRange(New DateTime(2009, 8, 1), New DateTime(2009, 8, 2)))

datePickerWithBlackoutDates.BlackoutDates.Add( _
    New CalendarDateRange(New DateTime(2009, 8, 8), New DateTime(2009, 8, 9)))

datePickerWithBlackoutDates.BlackoutDates.Add( _
    New CalendarDateRange(New DateTime(2009, 8, 15), New DateTime(2009, 8, 16)))

datePickerWithBlackoutDates.BlackoutDates.Add( _
    New CalendarDateRange(New DateTime(2009, 8, 22), New DateTime(2009, 8, 23)))

datePickerWithBlackoutDates.BlackoutDates.Add( _
    New CalendarDateRange(New DateTime(2009, 8, 29), New DateTime(2009, 8, 30)))

AddHandler datePickerWithBlackoutDates.DateValidationError, _
    AddressOf DatePicker_DateValidationError

' root is a Panel that is defined elsewhere. 
root.Children.Add(datePickerWithBlackoutDates)
<DatePicker Name="datePickerWithBlackoutDates"
            DisplayDateStart="8/1/09"
            DisplayDateEnd="8/31/09"
            SelectedDate="8/10/09"
            DateValidationError="DatePicker_DateValidationError">
  <DatePicker.BlackoutDates>
    <CalendarDateRange Start="8/1/09" End="8/2/09"/>
    <CalendarDateRange Start="8/8/09" End="8/9/09"/>
    <CalendarDateRange Start="8/15/09" End="8/16/09"/>
    <CalendarDateRange Start="8/22/09" End="8/23/09"/>
    <CalendarDateRange Start="8/29/09" End="8/30/09"/>
  </DatePicker.BlackoutDates>
</DatePicker>

The DatePicker handles the DateValidationError event, as shown in the following code. If the user enters a date that is not selectable, the example displays a message. If the user enters text that is not a valid date, an exception is thrown.

' If the text is a valid date, but a part of the 
' BlackoutDates collection, show a message. 
' If the text is not a valid date, thow an exception. 
Private Sub DatePicker_DateValidationError(ByVal sender As Object, _
                                           ByVal e As DatePickerDateValidationErrorEventArgs)

    Dim newDate As DateTime
    Dim datePickerObj As DatePicker = TryCast(sender, DatePicker)

    If DateTime.TryParse(e.Text, newDate) Then
        If datePickerObj.BlackoutDates.Contains(newDate) Then
            MessageBox.Show([String].Format("The date, {0}, cannot be selected.", e.Text))
        End If
    Else
        e.ThrowException = True
    End If
End Sub

.NET Framework
Available since 4.0
Silverlight
Available since 2.0
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