Question

在绑定到数据源的ItemsControl内，我尝试使用自定义验证规则验证TextBox，该规则接受参数，以下是vaildation规则的代码。 / p>

public class RatioValidation : ValidationRule
{
    public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo)
    {
        if (!String.IsNullOrEmpty(Maturity.MaturityValue) && Helper.IsDateInCorrectFormat(Maturity.MaturityValue))
        {
            String strVal = Convert.ToString(value);
            Double ratio = 0;
            Boolean isValid = Double.TryParse(strVal, out ratio);
            if (isValid)
            {
                if (ratio <= 0)
                    return new ValidationResult(false, "Please enter a valid ratio!");
                else return new ValidationResult(true, null);
            }
            return new ValidationResult(false, "Please enter a valid ratio!");
        }
        else return new ValidationResult(true, null);           
    }

    private MaturityDependencyForValidation _maturity;
    public MaturityDependencyForValidation Maturity
    {
        get { return _maturity; }
        set { _maturity = value; }
    }
}

public class MaturityDependencyForValidation : DependencyObject
{
    public String MaturityValue
    {
        get { return (String)GetValue(MaturityValueProperty); }
        set { SetValue(MaturityValueProperty, value); }
    }

    public static readonly DependencyProperty MaturityValueProperty =
        DependencyProperty.Register("MaturityValue", typeof(String), typeof(MaturityDependencyForValidation), new UIPropertyMetadata(null));

}

然后像下面一样使用它，

<TextBox Grid.Row="1" Grid.Column="2"  Name="txtRatio" BorderThickness="0" Width="148" Tag="{Binding StrMaturity, UpdateSourceTrigger=PropertyChanged}">
    <TextBox.Text>
        <Binding Path="Ratio" Mode="TwoWay"  UpdateSourceTrigger="PropertyChanged">
            <Binding.ValidationRules>
                <leg:RatioValidation ValidatesOnTargetUpdated="True">
                    <leg:RatioValidation.Maturity>
                         <leg:MaturityDependencyForValidation MaturityValue="{Binding txtMaturity}"/>
                    </leg:RatioValidation.Maturity>
                </leg:RatioValidation>
            </Binding.ValidationRules>
        </Binding>
    </TextBox.Text>
</TextBox>

我在输出窗口中出现异常：

无法为目标元素找到管理FrameworkElement或FrameworkContentElement。 BindingExpression：路径= txtMaturity;的DataItem = NULL; target元素是'MaturityDependencyForValidation'（HashCode = 63478077）; target属性是'Maturity'（类型'String'）

在RatioValidation规则中，Maturity的值永远不会受到数据绑定的约束。我需要这个数据绑定值。请帮忙。

Answer 1

周围的对象没有DataContext，至少绑定不是DependencyObjects，你的选择有点受限，它应该与{{3}时的情况相似}，另见binding in an array。

自定义验证规则WPF和项目控制

1 个答案: