根据类型选择数据模板 [英] Selecting a data template based on type

问题描述

我声明了以下类型:

public interface ITest { }
public class ClassOne : ITest { }
public class ClassTwo : ITest { }

在我的视图模型中，我声明并初始化以下集合:

In my viewmodel I'm declaring and initializing the following collection:

public class ViewModel
{
    public ObservableCollection<ITest> Coll { get; set; } = new ObservableCollection<ITest>
    {
        new ClassOne(),
        new ClassTwo()
    };  
}

在我看来，我声明以下ItemsControl

In my view I'm declaring the following ItemsControl

<ItemsControl ItemsSource="{Binding Coll}">
    <ItemsControl.Resources>
        <DataTemplate DataType="local:ClassOne">
            <Rectangle Width="50" Height="50" Fill="Red" />
        </DataTemplate>
        <DataTemplate DataType="local:ClassTwo">
            <Rectangle Width="50" Height="50" Fill="Blue" />
        </DataTemplate>
    </ItemsControl.Resources>
</ItemsControl>

我希望看到的是一个红色的正方形，然后是一个蓝色的正方形，相反，我看到的是以下内容:

What I expect to see is a red square followed by a blue square, instead what I see is the following:

我在做什么错了?

推荐答案

您的问题可能是由XAML的精细工作引起的.具体来说，您需要将Type传递给DataType，但是您传递的是带有类型名称的字符串.

Your issue might be caused by finnicky workings of XAML. Specifically, you need to pass Type to DataType, but you were passing a string with the name of the type.

使用x:Type装饰DataType的值，如下所示:

Use x:Type to decorate the value of DataType, like so:

<ItemsControl ItemsSource="{Binding Coll}">
    <ItemsControl.Resources>
        <DataTemplate DataType="{x:Type local:ClassOne}">
            <Rectangle Width="50" Height="50" Fill="Red" />
        </DataTemplate>
        <DataTemplate DataType="{x:Type local:ClassTwo}">
            <Rectangle Width="50" Height="50" Fill="Blue" />
        </DataTemplate>
    </ItemsControl.Resources>
</ItemsControl>

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