Question

尝试验证用户名文本框字段时遇到问题。当我失去焦点时我除了验证器显示错误。

我在其中创建了formptment ValidationRule

的UsernameValidator类

  public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo)
        {

            if (this.username == null)
                return new ValidationResult(false, "value cannot be empty.");
            else
            {
                if (this.username.ToString().Length > 3)
                    return new ValidationResult
                    (false, "Name cannot be more than 3 characters long.");
            }
            return ValidationResult.ValidResult;
        }

在xaml中我设置了控制模板

<ControlTemplate x:Key="validationErrorTemplate">
    <DockPanel>
    <StackPanel Orientation="Horizontal" DockPanel.Dock="Top">
        <Grid Width="12" Height="12">
            <Ellipse Width="12" Height="12" 
            Fill="Red" HorizontalAlignment="Center" 
            VerticalAlignment="Center"

                     ></Ellipse>
            <TextBlock Foreground="White" FontWeight="Heavy" 
            FontSize="8" HorizontalAlignment="Center" 
            VerticalAlignment="Center" TextAlignment="Center"
                       ToolTip="{Binding ElementName=ErrorAdorner, 
                       Path=AdornedElement.(Validation.Errors)[0].ErrorContent}"
                       >X</TextBlock>
        </Grid>
        <TextBlock Foreground="Red" FontWeight="12" Margin="2,0,0,0" 
                   Text="{Binding ElementName=ErrorAdorner, 
                   Path=AdornedElement.(Validation.Errors)[0].ErrorContent}"
                   ></TextBlock>                    
        </StackPanel>
        <AdornedElementPlaceholder 
        x:Name="ErrorAdorner" ></AdornedElementPlaceholder>
    </DockPanel>
</ControlTemplate>

对于我的textBox用户名，我声明

<TextBox x:Name="usernameTextBox" Validation.ErrorTemplate="{StaticResource validationErrorTemplate}" HorizontalAlignment="Left" Height="23" Margin="115,31,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="277" PreviewKeyDown="OnUsernameTextBoxKeyDown">
<TextBox.Text>
                <Binding Path="Username" Mode="TwoWay" UpdateSourceTrigger="LostFocus">
                    <Binding.ValidationRules>
                        <local:UsernameValidator></local:UsernameValidator>
                    </Binding.ValidationRules>
                </Binding>
            </TextBox.Text>
</TextBox

UsernameValidator类是我的验证类。

程序成功完成错误和更改。

我遵循本教程：http://www.codeproject.com/Tips/690130/Simple-Validation-in-WPF

Answer 1

WPF副设计默默地无法进行绑定操作（如同在正常操作期间没有向用户显示任何内容）。

但是，当您在调试器下运行WPF程序（例如Visual Studio中的Run + Debug按钮）时，您将看到“输出”窗口中显示的绑定错误。

WPF绑定验证未显示错误消息

1 个答案: