如何绑定到动态类型的属性？ [英] How to bind to a property of type dynamic?

问题描述

public interface IClassA
{
    string Description { get; set; }
    // more IClassA specific definitions
}

public interface IClassB
{
    string Description { get; set; }
    // more IClassB specific definitions
}

public class ClassA : IClassA
{
    public string Description { get; set; }
}

public class ClassB : IClassB
{
    public string Description { get; set; }
}

这是非常简化的代码。为简单起见，所有课程都缺少 INotifyPropertyChanged 实现。只需看看所有的代码，就好像它正确地实现了。

This is the very simplified code. All classes lack of INotifyPropertyChanged implementations for simplicity. Just watch all the code as if it was properly implementend.

将描述插入基本界面 IClassA 和 IClassB 不能被考虑， ，所以我很好奇动态通过WPF中的数据绑定绑定属性。这是我试过的：

Putting Description into a base interface for IClassA and IClassB can't be considered, yet, so I was curious about dynamic properties bound via data binding in WPF. This is, what I have tried:

public class CustomClass
{
    public dynamic Instance { get; set; }

    // passed instance is a ClassA or ClassB object
    public CustomClass(dynamic instance)
    {
        Instance = instance;
    }
}

我的Xaml包含一个 TextBlock ，其DataContext设置为 CutomClass 对象。如果我将 Instance 属性的类型更改为例如IClassA并正确填写，一切正常工作。

My Xaml contains a TextBlock, which has its DataContext set to a CutomClass object. If I change the Instance property's type to e.g. IClassA and fill it properly, everything works as expected. Not with dynamic though.

<TextBlock Text="{Binding Instance.Description}" />

VS2012中的Xaml Designer / ReSharper告诉我：无法解析数据中的属性描述 对象类型的上下文。

The Xaml Designer/ReSharper in VS2012 tells me:Cannot resolve property 'Description' in data context of type 'object'.

虽然 CodeInstance 被描述为动态的类型。但代码编译，所以我认为这可能是一个设计时问题。但是， TextBlock 仍然为空。

Though CodeInstance is described as type of dynamic. But the code compiled, so I thought that just might be a design-time issue. But the TextBlock remains empty.

我可能会误解原则 dynamic 在这种情况下，我不知道。因此，使用Google的搜索结果不足可能是由于不完全知道要搜索的内容而导致的。

I might misunderstand the principle dynamic in this case, I don't know. So the lack of search results by using Google might be caused by not exactly knowing what to search for.

推荐答案

您可以绑定到动态属性与任何属性相同。所以你的问题必须显示在别的地方，或者 ReSharper 正在给出另一个无益的错误，（讨厌该程序）

You can bind to a dynamic property the same way as any property. So your problem must be manifesting somewhere else, or ReSharper is giving yet another unhelpful error, (hate that program)

动态绑定示例：

Xaml：

<Window x:Class="WpfApplication7.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="104" Width="223" Name="UI">
    <StackPanel DataContext="{Binding ElementName=UI}">
        <TextBlock Text="{Binding MyProperty}" />
        <TextBlock Text="{Binding MyObject.MyProperty}" />
    </StackPanel>
</Window>

代码：

public partial class MainWindow : Window, INotifyPropertyChanged
{
    public MainWindow()
    {
        InitializeComponent();
        MyProperty = "Hello";
        MyObject = new ObjectTest { MyProperty = "Hello" };
    }

    private dynamic myVar;
    public dynamic MyProperty
    {
        get { return myVar; }
        set { myVar = value; NotifyPropertyChanged("MyProperty"); }
    }

    private dynamic myObject;
    public dynamic MyObject
    {
        get { return myObject; }
        set { myObject = value; NotifyPropertyChanged("MyObject"); }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    private void NotifyPropertyChanged(string p)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(p));
        }
    }
}

public class ObjectTest
{
    public string MyProperty { get; set; }
}

结果：

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