WPF RadioButton InverseBooleanConverter 不起作用 [英] WPF RadioButton InverseBooleanConverter not working

问题描述

我有两个 RadioButton，我将它们绑定到 ViewModel 中的一个布尔属性.不幸的是，我在转换器中遇到错误，因为targetType"参数为空.

I have two RadioButtons which I am binding to a boolean property in the ViewModel. Unfortunately I am getting an error in the converter because the 'targetType' parameter is null.

现在我不期望传入的 targetType 参数为 null(我期望 True 或 False).但是我注意到 RadioButton 的 IsChecked 属性是一个可为空的布尔值，所以这种解释是这样的.

Now I wasn't expecting the targetType parameter coming through to be null (I was expecting True or False). However I noticed that the IsChecked property of the RadioButton is a nullable bool so this kind of explains it.

我可以更正 XAML 中的某些内容，还是应该更改解决方案的现有转换器?

Can I correct something in the XAML or should I be changing the solution's existing converter?

这是我的 XAML:

<RadioButton Name="UseTemplateRadioButton" Content="Use Template" 
                GroupName="Template"
                IsChecked="{Binding UseTemplate, Mode=TwoWay}" />
<RadioButton Name="CreatNewRadioButton" Content="Create New"
                GroupName="Template"
                IsChecked="{Binding Path=UseTemplate, Mode=TwoWay, Converter={StaticResource InverseBooleanConverter}}"/>

这是我正在使用的解决方案范围内的现有转换器 InverseBooleanConverter:

This is the existing converter I am using solution wide InverseBooleanConverter:

public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
    if ((targetType != typeof(bool)) && (targetType != typeof(object)))
    {
        throw new InvalidOperationException("The target must be a boolean");
    }
    return !(((value != null) && ((IConvertible)value).ToBoolean(provider)));
} 

推荐答案

您需要更改转换器，或者使用新的转换器可能更好.

You need to change the converter, or what's probably even better, use a new converter.

[ValueConversion(typeof(bool?), typeof(bool))]
public class Converter : IValueConverter
{
    #region IValueConverter Members

    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (targetType != typeof(bool?))
        {
            throw new InvalidOperationException("The target must be a nullable boolean");
        }
        bool? b = (bool?)value;
        return b.HasValue && b.Value;
    } 

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return value;
    }

    #endregion
}

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