wpf 字典绑定，其中 key=variable [英] wpf dictionary binding where key=variable

问题描述

我有一本测试字典

MyDict = new Dictionary<string, Uri>
{
    {"First", new Uri("alma.jpg", UriKind.Relative)},
    {"Second", new Uri("korte.jpg", UriKind.Relative)}
};

和一个简单的 XAML

and a simple XAML

<TextBlock Text="{Binding MyDict[First]}"
           FontSize="13" Width="200" Height="30" />

这完美地显示了第一个关键元素值

That shows perfectly the First key element Value

我想要的是我有一个字符串变量:DictKey让 DictKey="First"

What I want is I have a string variable: DictKey Lets DictKey="First"

如何重写 XAML 以使用此变量

How to rewrite the XAML to use this variable

<TextBlock Text="{Binding MyDict[???DictKey????]}"
           FontSize="13" Width="200" Height="30" />

谢谢.

推荐答案

我假设您有一些属性 DictKey 保存项目的键.您可以使用 MultiBinding 并将第一个绑定设置为您的字典属性，并使用项目的键将第二个绑定设置为该属性:

I assume you have some property DictKey which holds the key of the item. You can use MultiBinding and set the first binding to your dictionary property and second binding to the property with the key of the item:

<TextBlock FontSize="13" Width="200" Height="30">
    <TextBlock.Text>
        <MultiBinding>
            <MultiBinding.Converter>
                <local:DictionaryItemConverter/>
            </MultiBinding.Converter>

            <Binding Path="MyDict"/>
            <Binding Path="DictKey"/>
        </MultiBinding>
    </TextBlock.Text>
</TextBlock>

转换器使用这两个值从字典中读取项目:

The converter uses both values to read the item from dictionary:

public class DictionaryItemConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        if (values != null && values.Length >= 2)
        {
            var myDict = values[0] as IDictionary;
            var myKey = values[1] as string;
            if (myDict != null && myKey != null)
            {
                //the automatic conversion from Uri to string doesn't work
                //return myDict[myKey];
                return myDict[myKey].ToString();
            }
        }
        return Binding.DoNothing;
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotSupportedException();
    }
}

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