检测WPF验证错误

在WPF中,您可以使用ExceptionValidationRule或在数据绑定期间根据数据层中抛出的错误设置验证DataErrorValidationRule.

假设你有一堆这样设置的控件,你有一个Save按钮.当用户单击"保存"按钮时,您需要确保在继续保存之前没有验证错误.如果存在验证错误,您希望对它们大声疾呼.

在WPF中,如何确定是否有任何数据绑定控件设置了验证错误？

1> 小智..：

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这篇文章非常有帮助.感谢所有贡献者.这是一个你会喜欢或讨厌的LINQ版本.

private void CanExecute(object sender, CanExecuteRoutedEventArgs e)
{
    e.CanExecute = IsValid(sender as DependencyObject);
}

private bool IsValid(DependencyObject obj)
{
    // The dependency object is valid if it has no errors and all
    // of its children (that are dependency objects) are error-free.
    return !Validation.GetHasError(obj) &&
    LogicalTreeHelper.GetChildren(obj)
    .OfType()
    .All(IsValid);
}

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只是想知道,你怎么称呼'IsValid`功能？我看到你已经设置了一个`CanExecute`我猜它与Save按钮的命令有关.如果我不使用命令,这会工作吗？按钮如何与其他需要检查的控件相关？我唯一想到如何使用它的方法是为每个需要验证的控件调用`IsValid`.**编辑:**好像你正在验证我希望成为保存按钮的`sender`.这对我来说似乎不对.

2> aogan..：

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以下代码(来自Chris Sell和Ian Griffiths的Programming WPF一书)验证了依赖对象及其子代的所有绑定规则:

public static class Validator
{

    public static bool IsValid(DependencyObject parent)
    {
        // Validate all the bindings on the parent
        bool valid = true;
        LocalValueEnumerator localValues = parent.GetLocalValueEnumerator();
        while (localValues.MoveNext())
        {
            LocalValueEntry entry = localValues.Current;
            if (BindingOperations.IsDataBound(parent, entry.Property))
            {
                Binding binding = BindingOperations.GetBinding(parent, entry.Property);
                foreach (ValidationRule rule in binding.ValidationRules)
                {
                    ValidationResult result = rule.Validate(parent.GetValue(entry.Property), null);
                    if (!result.IsValid)
                    {
                        BindingExpression expression = BindingOperations.GetBindingExpression(parent, entry.Property);
                        System.Windows.Controls.Validation.MarkInvalid(expression, new ValidationError(rule, expression, result.ErrorContent, null));
                        valid = false;
                    }
                }
            }
        }

        // Validate all the bindings on the children
        for (int i = 0; i != VisualTreeHelper.GetChildrenCount(parent); ++i)
        {
            DependencyObject child = VisualTreeHelper.GetChild(parent, i);
            if (!IsValid(child)) { valid = false; }
        }

        return valid;
    }

}

您可以在页面/窗口中的保存按钮单击事件处理程序中调用此方法

private void saveButton_Click(object sender, RoutedEventArgs e)
{

  if (Validator.IsValid(this)) // is valid
   {

    ....
   }
}

3> H-Man2..：

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使用ListBox时,发布的代码对我不起作用.我重写了它,现在它的工作原理:

public static bool IsValid(DependencyObject parent)
{
    if (Validation.GetHasError(parent))
        return false;

    // Validate all the bindings on the children
    for (int i = 0; i != VisualTreeHelper.GetChildrenCount(parent); ++i)
    {
        DependencyObject child = VisualTreeHelper.GetChild(parent, i);
        if (!IsValid(child)) { return false; }
    }

    return true;
}

4> 小智..：

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有同样的问题,并尝试提供的解决方案.H-Man2和skiba_k解决方案的组合对我来说几乎没问题,但有一个例外:My Window有一个TabControl.并且仅针对当前可见的TabItem评估验证规则.所以我用LogicalTreeHelper替换了VisualTreeHelper.现在它有效.

    public static bool IsValid(DependencyObject parent)
    {
        // Validate all the bindings on the parent
        bool valid = true;
        LocalValueEnumerator localValues = parent.GetLocalValueEnumerator();
        while (localValues.MoveNext())
        {
            LocalValueEntry entry = localValues.Current;
            if (BindingOperations.IsDataBound(parent, entry.Property))
            {
                Binding binding = BindingOperations.GetBinding(parent, entry.Property);
                if (binding.ValidationRules.Count > 0)
                {
                    BindingExpression expression = BindingOperations.GetBindingExpression(parent, entry.Property);
                    expression.UpdateSource();

                    if (expression.HasError)
                    {
                        valid = false;
                    }
                }
            }
        }

        // Validate all the bindings on the children
        System.Collections.IEnumerable children = LogicalTreeHelper.GetChildren(parent);
        foreach (object obj in children)
        {
            if (obj is DependencyObject)
            {
                DependencyObject child = (DependencyObject)obj;
                if (!IsValid(child)) { valid = false; }
            }
        }
        return valid;
    }

5> 小智..：

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除了Dean的出色LINQ实现之外,我还很乐意将代码包装到DependencyObjects的扩展中:

public static bool IsValid(this DependencyObject instance)
{
   // Validate recursivly
   return !Validation.GetHasError(instance) &&  LogicalTreeHelper.GetChildren(instance).OfType().All(child => child.IsValid());
}

考虑到重复使用,这非常好.