我想绑定到词典＆LT;型号，串＆GT;通过XAML

现在的问题是，索引 [] 在绑定标记扩展跨$ P $点是为内容串。是否有某种反向转义序列的那种情况？

The problem is, the indexer [] in the Binding markup extension interprets it's content as string. Is there some kind of 'unescape-sequence' for that case?

<TextBox Text="{Binding theDictionary[{x:Type ns:OnePrettyType}]}" />

（绑定不工作，因为 {X：NS类型：一prettyType} 正在发送的字符串）

(Binding doesn't work because {x:Type ns:OnePrettyType} is being sent as string)

推荐答案

如果索引器都有特定的类型转换应该自动完成所以这应该工作：

If the indexer has a specific type the conversion should be done automatically so this should work:

{Binding theDictionary[ns:OnePrettyType]}

如果你需要一个明确的跨pretation可以尝试投是这样的：

If you need an explicit interpretation you can try a "cast" like this:

{Binding theDictionary[(sys:Type)ns:OnePrettyType]}

（这里的 SYS 映射到进程的系统命名空间）

(Where sys is mapped to the System namespace of course)

这将是理论，但所有这一切将无法正常工作。首先，如果你使用绑定构造函数的路径中投将被忽略，因为它使用的PropertyPath以一定的方式。你也将获得一个绑定错误：

That would be the theory but all of that won't work. First of all if you use the Binding constructor that takes a path the cast will be ignored as it uses a certain constructor of PropertyPath in a certain way. Also you will get a binding error:

System.Windows.Data错误：40：BindingEx pression路径错误：'[]'属性不是'对象'发现''Dictionary`2

System.Windows.Data Error: 40 : BindingExpression path error: '[]' property not found on 'object' ''Dictionary`2'

您需要使其构造的PropertyPath 通过类型转换器通过避免绑定构造器：

You would need to make it construct the PropertyPath via the type converter by avoiding the Binding constructor:

{Binding Path=theDictionary[(sys:Type)ns:OnePrettyType]}

现在，这将极有可能只是抛出一个异常：

Now this will most likely just throw an exception:

{路径索引器参数的值，它不能被解析为指定的类型：SYS：类型}

{"Path indexer parameter has value that cannot be resolved to specified type: 'sys:Type'"}

因此​​，有不幸的是，没有默认的类型转换正在进行。然后，您可以构造一个的PropertyPath 在XAML，并确保一个类型传入，但类并不意味着在XAML中使用，如果你尝试将抛出一个异常，也很不幸。

So there unfortunately is no default type conversion going on. You could then construct a PropertyPath in XAML and make sure a type is passed in, but the class is not meant to be used in XAML and will throw an exception if you try, also very unfortunate.

一种解决方法是创建一个标记扩展由它来完成建设，如：

One workaround would be to create a markup extension which does the construction, e.g.

[ContentProperty("Parameters")]
public class PathConstructor : MarkupExtension
{
    public string Path { get; set; }
    public IList Parameters { get; set; }

    public PathConstructor()
    {
        Parameters = new List<object>();
    }
    public PathConstructor(string path, object p0)
    {
        Path = path;
        Parameters = new[] { p0 };
    }

    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        return new PropertyPath(Path, Parameters.Cast<object>().ToArray());
    }
}

然后可以使用这样的：

Which then can be used like this:

<Binding>
    <Binding.Path>
        <me:PathConstructor Path="theDictionary[(0)]">
            <x:Type TypeName="ns:OnePrettyType" />
        </me:PathConstructor>
    </Binding.Path>
</Binding>

或像这样

{Binding Path={me:PathConstructor theDictionary[(0)], {x:Type ns:OnePrettyType}}}