如何在WPF中扩展控件以在ErrorTemplate中为错误消息腾出空间?

编辑:好吧,我不确定这是最好的解决方案(我当然希望有人能提供更好的解决方案),但这里是:

您可以添加一些文本块并将它们绑定到Validation.HasError和(Validation.Errors)[0].ErrorContent,而不是使用Validation.ErrorTeplate(它将显示AdornerLayer中的所有视觉效果),使用客户IValueConverter将Validation.HasError bool转换为可见性值。它看起来类似于以下内容:

Window1.cs:

<Window x:Class="WpfApplicationTest.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:sys="clr-namespace:System;assembly=mscorlib"
    xmlns:local="clr-namespace:WpfApplicationTest"
    Title="Window1" Height="300" Width="300">
    <Grid Margin="10">
        <Grid.Resources>
            <!-- The person we are binding to -->
            <local:Person x:Key="charles" Name="Charles" Age="20" />
            <!-- The convert to use-->
            <local:HasErrorToVisibilityConverter x:Key="visibilityConverter" />
        </Grid.Resources>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        <!-- The name -->
        <TextBox Name="NameTextBox" Grid.Row="0" Text="{Binding Source={StaticResource charles}, Path=Name, ValidatesOnDataErrors=true}" />
        <TextBlock Grid.Row="1" 
                   Foreground="Red" 
                   Text="{Binding ElementName=NameTextBox, Path=(Validation.Errors)[0].ErrorContent}" 
                   Visibility="{Binding ElementName=NameTextBox, Path=(Validation.HasError), Converter={StaticResource visibilityConverter}}" />

        <!-- The age -->
        <TextBox Name="AgeTextBox" Grid.Row="2" Text="{Binding Source={StaticResource charles}, Path=Age, ValidatesOnExceptions=true}" />
        <TextBlock Grid.Row="3" 
                   Foreground="Red" 
                   Text="{Binding ElementName=AgeTextBox, Path=(Validation.Errors)[0].ErrorContent}" 
                   Visibility="{Binding ElementName=AgeTextBox, Path=(Validation.HasError), Converter={StaticResource visibilityConverter}}" />
    </Grid>
</Window>

Person.cs:

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

namespace WpfApplicationTest
{
    public class Person : IDataErrorInfo
    {
        public string Name { get; set; }
        public int Age { get; set; }

        #region IDataErrorInfo Members

        string IDataErrorInfo.Error
        {
            get { throw new NotImplementedException(); }
        }

        string IDataErrorInfo.this[string columnName]
        {
            get
            {
                switch (columnName)
                {
                    case ("Name"):
                        if (Regex.IsMatch(this.Name, "[^a-zA-Z ]"))
                        {
                            return "Name may contain only letters and spaces.";
                        }
                        else
                        {
                            return null;
                        }
                    default:
                        return null;
                }
            }
        }

        #endregion
    }
}

HasErrorToVisibilityConverter.cs:

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

namespace WpfApplicationTest
{
    [ValueConversion(typeof(bool), typeof(Visibility))]
    public class HasErrorToVisibilityConverter : IValueConverter
    {
        #region IValueConverter Members

        object IValueConverter.Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            bool hasError = (bool)value;
            return hasError ? Visibility.Visible : Visibility.Collapsed;
        }

        object IValueConverter.ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            throw new NotImplementedException();
        }

        #endregion
    }
}

它的可伸缩性不如拥有一个可以在所有控件中引用的控件模板,但这是我找到的唯一解决方案。我感觉到了你的痛苦——我能找到的关于WPF验证的每个例子都非常简单,而且几乎总是使用“!”或控件前面的“*”,工具提示绑定到(Validation.Errors)[0]。ErrorContent。。。

祝你好运!如果我找到更好的解决方案,我将更新此;)