MVVM-Light ViewModelLocator可以在嵌套ViewModel中使用吗? [英] Can the MVVM-Light ViewModelLocator be used in nested ViewModels?

问题描述

Visual Studio 2008设计器似乎不喜欢引用MVVM-Light ViewModelLocator的UserControl.我收到如下错误消息:

The Visual Studio 2008 Designer doesn't seem to like UserControls that reference the MVVM-Light ViewModelLocator. I get an error message like:

无法创建类型为"MyUserControl"的实例.

Could not create an instance of type 'MyUserControl'.

例如，如果MyUserControl使用ViewModelLocator建立其DataContext，则以下XAML会导致此行为.

For example, the following XAML will cause this behavior if MyUserControl uses the ViewModelLocator to establish its DataContext.

<Page x:Class="MyProject.Views.MainView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:Views="clr-namespace:MyProject.Views"
>
    <Grid>
        <Views:MyUserControl/>
    </Grid>
</Page>

MyUserControl非常简单:

MyUserControl is extremely simple:

<UserControl x:Class="MyProject.Views.MyUserControl"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         DataContext="{Binding MyNestedViewModel, Source={StaticResource Locator}}"
>
<Grid>
    <TextBlock>Hello</TextBlock>
</Grid>
</UserControl>

"MyNestedViewModel"属性只是实例化MyNestedViewModel类的实例，该类的默认构造函数中绝对没有代码.

And the "MyNestedViewModel" property simply instantiates an instance of the MyNestedViewModel class, which has absolutely no code in its default constructor.

两个问题:

1. 我是否正确使用ViewModelLocator?也就是说，它可以在嵌套视图中使用还是仅用于顶级视图?
2. 这可能只是Visual Studio 2008设计器Cider中的另一个错误吗?

请注意，一切都在运行时完美运行.我只在设计时遇到问题.但是我讨厌对XAML进行盲目编码.

Note that everything works perfectly at runtime. I only have problems at design time. But I hate coding XAML blind.

推荐答案

我在VS 2010中遇到了同样的情况.我只是发现了部分解决方法...

I encounter the same situation in VS 2010. A partial workaround I JUST discovered...

在您的UserControl中，将DataContext更改为d:DataContext

In your UserControl, change DataContext to d:DataContext

<UserControl x:Class="MyProject.Views.MyUserControl"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         d:DataContext="{Binding MyNestedViewModel, Source={StaticResource Locator}}"
>
<Grid>
    <TextBlock>Hello</TextBlock>
</Grid>
</UserControl>

不幸的是，我无法让它在UserControl YET中显示数据，而只是在UserControl本身中显示.

Unfortunately, I can't get it to display data in the UserControl YET, just the UserControl itself.

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