WPF ExceptionValidationRule未显示在Validation.Errors集合中

Question

如果FirstName值为null或为空,我正在抛出一个ApplicationException,我试图在TextBlock中显示错误消息,该消息是ErrorTemplate的一部分.但它始终显示"异常已被抛出调用目标".

public string FirstName
        {
            get { return _firstName;}
            set
            {
                if(String.IsNullOrEmpty(value))
                    throw new ApplicationException("FirstName cannot be null or empty!");
                _firstName = value; 

                OnPropertyChanged("FirstName");
            }
        }

<Style x:Key="TextBoxStyle" TargetType="TextBox">

            <Setter Property="Validation.ErrorTemplate">
                <Setter.Value>
                    <ControlTemplate>
                        <DockPanel LastChildFill="True">
                            <TextBlock DockPanel.Dock="Right"
                        Foreground="Orange"
                        FontSize="12pt"
                        Text="{Binding ElementName=MyAdorner, Path=AdornedElement.(Validation.Errors)[0].ErrorContent}">
                            </TextBlock>
                            <Border BorderBrush="Green" BorderThickness="1">
                                <AdornedElementPlaceholder Name="MyAdorner" />
                            </Border>
                        </DockPanel>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>

        </Style>

最后这里是TextBox控件:

<TextBox Name="txtFirstName" Style="{StaticResource TextBoxStyle}" Grid.Column="1"  Grid.Row="0" Height="20" Width="100" Margin="10">
                <TextBox.Text>
                    <Binding Path="FirstName">
                        <Binding.ValidationRules>
                            <ExceptionValidationRule />
                        </Binding.ValidationRules>
                    </Binding>
                </TextBox.Text>

            </TextBox>

Answer 1

前几天我经历了这个,最后我从属性中取出了异常并使用了验证类.

<TextBox Name="txtFirstName" Style="{StaticResource TextBoxStyle}" Grid.Column="1"  Grid.Row="0" Height="20" Width="100" Margin="10">
        <TextBox.Text>
            <Binding Path="FirstName" >
                <Binding.ValidationRules>
                    <validators:StringRangeValidationRule 
                                    MinimumLength="1" 
                                    MaximumLength="40"
                                    ErrorMessage="Required" />
                </Binding.ValidationRules>
            </Binding>
        </TextBox.Text>

从您的属性中删除异常,所以它看起来像这样......

private string _firstName;
    public string FirstName
    {
        get { return _firstName; }
        set
        {
            _firstName = value;

            OnPropertyChanged("FirstName");
        }
    }

继承人验证课程(我在互联网上偷了这个)...

public class StringRangeValidationRule : ValidationRule
{
    private int _minimumLength = -1;
    private int _maximumLength = -1;
    private string _errorMessage;

    public int MinimumLength
    {
        get { return _minimumLength; }
        set { _minimumLength = value; }
    }

    public int MaximumLength
    {
        get { return _maximumLength; }
        set { _maximumLength = value; }
    }

    public string ErrorMessage
    {
        get { return _errorMessage; }
        set { _errorMessage = value; }
    }

    public override ValidationResult Validate(object value,
        CultureInfo cultureInfo)
    {
        ValidationResult result = new ValidationResult(true, null);
        string inputString = (value ?? string.Empty).ToString();
        if (inputString.Length < this.MinimumLength ||
               (this.MaximumLength > 0 &&
                inputString.Length > this.MaximumLength))
        {
            result = new ValidationResult(false, this.ErrorMessage);
        }
        return result;
    }
}

你需要在你的xaml中添加一个命名空间引用到验证类所在的地方,称为验证器(我确定你知道这一点,但仅仅是为了完整性)

就像是 ...

xmlns:validators="clr-namespace:WpfApplication1"

希望这可以帮助!

干杯,

安迪