具有多个(故障) ValidationRules的BindingGroup

Question

我今天在工作中遇到了一个问题，我的一个BindingGroup有多个ValidationRule同时发生故障。问题是，当我尝试确定是否有任何错误时(例如，将命令上的CanExecute设置为false)，我从BindingGroup.ValidateWithoutUpdate中得到了一个ArgumentException冒泡。

我已经成功地将其提炼为以下示例(抱歉，它仍然跨越多个来源，但我已经将应该复制/粘贴到新的WPF项目中的所有相关部分封装在一起)：

Window1.xaml：

<Window 
    x:Class="BindingGroupTest.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:l="clr-namespace:BindingGroupTest"
    xmlns:diag="clr-namespace:System.Diagnostics;assembly=WindowsBase"
    Title="Window1" Height="300" Width="300">

    <Window.BindingGroup>
        <BindingGroup Name="RootBindingGroup">
            <BindingGroup.ValidationRules>
                <l:TestRule1 />
                <l:TestRule2 />
            </BindingGroup.ValidationRules>
        </BindingGroup>
    </Window.BindingGroup>

    <StackPanel>
        <TextBox Text="{Binding 
            Path=Name, 
            BindingGroupName=RootBindingGroup,
            UpdateSourceTrigger=PropertyChanged,
            diag:PresentationTraceSources.TraceLevel=High}" />
        <TextBox Text="{Binding 
            Path=Age, 
            BindingGroupName=RootBindingGroup,
            UpdateSourceTrigger=PropertyChanged,
            diag:PresentationTraceSources.TraceLevel=High}" />
        <Button Content="Validate" Click="DoValidate" />
    </StackPanel>
</Window>

Window1.xaml.cs：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace BindingGroupTest
{
    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1()
        {
            this.DataContext = new Person()
            {
                Name="Test",
                Age=30,
            };

            InitializeComponent();

            this.BindingGroup.BeginEdit();
        }

        private void DoValidate(object sender, RoutedEventArgs e)
        {
            try
            {
                if (!this.BindingGroup.ValidateWithoutUpdate())
                    MessageBox.Show("Validation failed!");
                else
                    MessageBox.Show("Validation passed!");
            }
            catch (Exception ex)
            {
                var msg = "While validating, caught exception: " + ex.Message;
                MessageBox.Show(msg);
            }
        }
    }
}

Person.cs：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace BindingGroupTest
{
    public class Person
    {
        public string Name { get; set; }
        public int Age { get; set; }
    }
}

TestRule1.cs：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;

namespace BindingGroupTest
{
    public class TestRule1 : ValidationRule
    {
        public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo)
        {
            var p = ((BindingGroup)value).Items[0] as Person;
            if (p == null)
                return ValidationResult.ValidResult;

            if (p.Age < 0)
                return new ValidationResult(false, "Surely, you've been born yet!");

            return ValidationResult.ValidResult;
        }
    }
}

测试规则2.cs：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;

namespace BindingGroupTest
{
    public class TestRule2 : ValidationRule
    {
        public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo)
        {
            var p = ((BindingGroup)value).Items[0] as Person;
            if (p == null)
                return ValidationResult.ValidResult;

            if (string.IsNullOrEmpty(p.Name))
                return new ValidationResult(false, "What, no name?");

            return ValidationResult.ValidResult;
        }
    }
}

基本上，我的问题是如果TestRule1和TestRule2fail, I get anArgumentExceptionbubbling up when I callthis.BindingGroup.ValidateWithoutUpdate()with message "Cannot have duplicates in this Collection", parameter name: "validationError". I dug around through the implementation ofBindingGroup, and it seems that it is using itself as the second parameter toValidationError, which is thebindingInErrorparameter, which the underlyingValidationErrorCollection`都要求是唯一的。

诚然，这个例子是人为的，然而，它完美地展示了我的现实世界中不是的问题。(我有两个完全独立的ValidationRule，它们在同一个业务对象的不同属性上操作，将它们折叠到一个ValidationRule中是没有意义的)。此外，我能找到的每个使用BindingGroup的示例都只演示了单个ValidationRule的使用，但是该构造显然支持并接受多个规则，尽管很明显，只要一次只有一个失败。

是我做错了什么，还是像我目前倾向于认为的那样，这似乎是BindingGroup实现中的一个错误。

值得一提的是，我将VS2008与.Net 3.5 SP1一起使用。

Answer 1

如果你在.NET 4.0中运行它，它将以你期望的方式工作，所以看起来它确实是一个错误，并在下一个版本中得到了修复。