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ValidationStep Enumeration

 

Specifies when a ValidationRule runs.

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

Public Enumeration ValidationStep

Member nameDescription
CommittedValue

Runs the ValidationRule after the value has been committed to the source.

ConvertedProposedValue

Runs the ValidationRule after the value is converted.

RawProposedValue

Runs the ValidationRule before any conversion occurs.

UpdatedValue

Runs the ValidationRule after the source is updated.

The following example uses a ValidationRule named ValidateDateAndPrice. The ValidationStep for this rule is set to ConvertedProposedValue so that when it runs, the Validate method has access to values that are of the source property's type.

When the PriceIsAPositiveNumber and FutureDateRule rules run, the values in each Validate method are strings because the default value of ValidationStep is RawProposedValue. Therefore, the rules run before the values are converted to their respective types.

<StackPanel Name="stackPanel1"  Margin="10" Width="250"
            Loaded="stackPanel1_Loaded"
            Validation.Error="ItemError">

  <StackPanel.Resources>
    <Style TargetType="HeaderedContentControl">
      <Setter Property="Margin" Value="2"/>
      <Setter Property="Focusable" Value="False"/>
      <Setter Property="Template">
        <Setter.Value>
          <ControlTemplate TargetType="HeaderedContentControl">
            <DockPanel LastChildFill="False">
              <ContentPresenter ContentSource="Header" DockPanel.Dock="Left" Focusable="False" VerticalAlignment="Center"/>
              <ContentPresenter ContentSource="Content" Margin="5,0,0,0" DockPanel.Dock="Right" VerticalAlignment="Center"/>
            </DockPanel>

          </ControlTemplate>
        </Setter.Value>
      </Setter>
    </Style>

    <Style TargetType="Button">
      <Setter Property="Width" Value="100"/>
      <Setter Property="Margin" Value="10,15,15,15"/>

    </Style>

  </StackPanel.Resources>

  <StackPanel.BindingGroup>
    <BindingGroup NotifyOnValidationError="True">
      <BindingGroup.ValidationRules>
        <src:ValidateDateAndPrice ValidationStep="ConvertedProposedValue" />
      </BindingGroup.ValidationRules>
    </BindingGroup>
  </StackPanel.BindingGroup>

  <TextBlock FontSize="14" Text="Enter an item for sale"/>
  <HeaderedContentControl Header="Description">
    <TextBox Width="150" Text="{Binding Path=Description, Mode=TwoWay}"/>
  </HeaderedContentControl>
  <HeaderedContentControl Header="Price">
    <TextBox Name="priceField"  Width="150">
      <TextBox.Text>
        <Binding Path="Price" Mode="TwoWay" >
          <Binding.ValidationRules>
            <src:PriceIsAPositiveNumber/>
          </Binding.ValidationRules>
        </Binding>
      </TextBox.Text>
    </TextBox>
  </HeaderedContentControl>
  <HeaderedContentControl Header="Date Offer Ends">
    <TextBox Name="dateField" Width="150" >
      <TextBox.Text>
        <Binding Path="OfferExpires" StringFormat="d" >
          <Binding.ValidationRules>
            <src:FutureDateRule/>
          </Binding.ValidationRules>
        </Binding>
      </TextBox.Text>
    </TextBox>
  </HeaderedContentControl>
  <StackPanel Orientation="Horizontal">
    <Button IsDefault="True" Click="Submit_Click">_Submit</Button>
    <Button IsCancel="True" Click="Cancel_Click">_Cancel</Button>
  </StackPanel>
  <HeaderedContentControl Header="Description">
    <TextBlock Width="150" Text="{Binding Path=Description}"/>
  </HeaderedContentControl>
  <HeaderedContentControl Header="Price">
    <TextBlock Width="150" Text="{Binding Path=Price, StringFormat=c}"/>
  </HeaderedContentControl>
  <HeaderedContentControl Header="Date Offer Ends">
    <TextBlock Width="150" Text="{Binding Path=OfferExpires, StringFormat=d}"/>
  </HeaderedContentControl>
</StackPanel>

The following example shows the ValidateDateAndPriceValidationRule. In the Validate method, the Price property is of type Double and the OfferExpires property is of type DateTime. The strings have been converted to their respective types by the time the ValidationRule runs.

Public Class ValidateDateAndPrice
	Inherits ValidationRule
	' Ensure that an item over $100 is available for at least 7 days.
	Public Overrides Function Validate(ByVal value As Object, ByVal cultureInfo As CultureInfo) As ValidationResult
		Dim bg As BindingGroup = TryCast(value, BindingGroup)

		' Get the source object.
		Dim item As PurchaseItem = TryCast(bg.Items(0), PurchaseItem)

           Dim doubleValue As Object = Nothing
           Dim dateTimeValue As Object = Nothing

		' Get the proposed values for Price and OfferExpires.
		Dim priceResult As Boolean = bg.TryGetValue(item, "Price", doubleValue)
		Dim dateResult As Boolean = bg.TryGetValue(item, "OfferExpires", dateTimeValue)

		If (Not priceResult) OrElse (Not dateResult) Then
			Return New ValidationResult(False, "Properties not found")
		End If

		Dim price As Double = CDbl(doubleValue)
		Dim offerExpires As Date = CDate(dateTimeValue)

		' Check that an item over $100 is available for at least 7 days.
		If price > 100 Then
			If offerExpires < Date.Today + New TimeSpan(7, 0, 0, 0) Then
				Return New ValidationResult(False, "Items over $100 must be available for at least 7 days.")
			End If
		End If

		Return ValidationResult.ValidResult

	End Function
End Class

.NET Framework
Available since 3.0
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