WPF表单数据验证

Validation.ErrorTemplate模板定义与应用
最后几句TextBox的样式把模板应用到了TextBox

<ControlTemplate x:Key="validationTemplate">
        <StackPanel>
            <Border BorderThickness="1"
                    BorderBrush="Red"
                    Opacity="0">
                <Border.Triggers>
                    <EventTrigger RoutedEvent="Loaded">
                        <BeginStoryboard>
                            <Storyboard BeginTime="0:0:0.000">
                                <DoubleAnimation BeginTime="0:0:0.000"
                                                 Storyboard.TargetProperty="Opacity"
                                                 Duration="0:0:0.300"
                                                 To="1" />
                                <DoubleAnimation BeginTime="0:0:0.300"
                                                 Storyboard.TargetProperty="Opacity"
                                                 Duration="0:0:0.300"
                                                 To="0" />
                                <DoubleAnimation BeginTime="0:0:0.600"
                                                 Storyboard.TargetProperty="Opacity"
                                                 Duration="0:0:0.300"
                                                 To="1" />
                                <DoubleAnimation BeginTime="0:0:0.900"
                                                 Storyboard.TargetProperty="Opacity"
                                                 Duration="0:0:0.300"
                                                 To="0" />
                                <DoubleAnimation BeginTime="0:0:1.200"
                                                 Storyboard.TargetProperty="Opacity"
                                                 Duration="0:0:0.300"
                                                 To="1" />
                                <DoubleAnimation BeginTime="0:0:1.500"
                                                 Storyboard.TargetProperty="Opacity"
                                                 Duration="0:0:0.300"
                                                 To="0" />
                                <DoubleAnimation BeginTime="0:0:1.800"
                                                 Storyboard.TargetProperty="Opacity"
                                                 Duration="0:0:0.300"
                                                 To="1" />
                                <DoubleAnimation BeginTime="0:0:2.100"
                                                 Storyboard.TargetProperty="Opacity"
                                                 Duration="0:0:0.300"
                                                 To="0" />
                                <DoubleAnimation BeginTime="0:0:2.400"
                                                 Storyboard.TargetProperty="Opacity"
                                                 Duration="0:0:0.300"
                                                 To="1" />
                                <DoubleAnimation BeginTime="0:0:2.700"
                                                 Storyboard.TargetProperty="Opacity"
                                                 Duration="0:0:0.300"
                                                 To="0" />
                                <DoubleAnimation BeginTime="0:0:3.000"
                                                 Storyboard.TargetProperty="Opacity"
                                                 Duration="0:0:0.300"
                                                 To="1" />
                            </Storyboard>
                        </BeginStoryboard>
                    </EventTrigger>
                </Border.Triggers>
                <AdornedElementPlaceholder Name="placeholder">
                    <Popup Name="ValidationPopup"
                           AllowsTransparency="true"
                           IsOpen="false"
                           PlacementTarget="{Binding ElementName=placeholder, Mode=OneWay}">
                        <Grid Name="Root"
                              Margin="4">
                            <Border Background="LightGray"
                                    CornerRadius="2">
                                <Border.Resources>
                                    <DataTemplate DataType="{x:Type ValidationError}">
                                        <TextBlock MaxWidth="250"
                                                   Margin="8,4"
                                                   Foreground="Red"
                                                   TextWrapping="Wrap"
                                                   UseLayoutRounding="false"
                                                   Text="{Binding ErrorContent}" />
                                    </DataTemplate>
                                </Border.Resources>
                                <ItemsControl ItemsSource="{Binding}" />
                            </Border>
                        </Grid>
                    </Popup>
                </AdornedElementPlaceholder>
            </Border>
        </StackPanel>
        <ControlTemplate.Triggers>
            <MultiDataTrigger>
                <MultiDataTrigger.Conditions>
                    <Condition Binding="{Binding ElementName=placeholder, Path=AdornedElement.IsKeyboardFocusWithin, Mode=OneWay}"
                               Value="True" />
                    <Condition Binding="{Binding ElementName=placeholder, Path=AdornedElement.(Validation.HasError), Mode=OneWay}"
                               Value="True" />
                </MultiDataTrigger.Conditions>
                <Setter TargetName="ValidationPopup"
                        Property="IsOpen"
                        Value="true" />
            </MultiDataTrigger>
        </ControlTemplate.Triggers>
    </ControlTemplate>

    <Style TargetType="{x:Type TextBox}">
        <Setter Property="Validation.ErrorTemplate"
                Value="{StaticResource validationTemplate}" />
    </Style>

Xaml中应用验证模板

注意：绑定实体属性时，要设置ValidatesOnDataErrors=True，才会触发数据验证

<Grid Margin="5"
                  Grid.Row="1">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto"
                                      SharedSizeGroup="label" />
                    <ColumnDefinition />
                </Grid.ColumnDefinitions>
                <TextBlock Text="{StaticResource UserName}"
                           VerticalAlignment="Center"
                           Margin="0,0,10,0"></TextBlock>
                <TextBlock Text="*"
                           VerticalAlignment="Center"
                           Foreground="Red"
                           HorizontalAlignment="Right"
                           FontWeight="Bold"
                           FontSize="16"
                           ToolTip="必选项"></TextBlock>
                <TextBox Grid.Column="1"
                         Text="{Binding User.UserName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}"
                         Validation.ErrorTemplate="{StaticResource validationTemplate}"></TextBox>
            </Grid>