如何基于 DataTemplate 的 DataContext 对象创建 ViewModel? [英] How do I create a ViewModel based on the DataContext object of a DataTemplate?

问题描述

我使用 MVVM 已经有一段时间了，这个问题(如果是问题的话)一直困扰着我.

I've been working with MVVM for a while, and this problem (if it is a problem) has me stumped all the time.

我有一个 ItemsControl 绑定到我的 MainViewModel 中的一个集合

I have an ItemsControl bound to a collection in my MainViewModel

视图模型

public class MainViewModel : ViewModelBase
{
    public ObservableCollection<string> Names { get; set; }
}

XAML

<ItemsControl ItemsSource="{Binding Names}">
  <ItemsControl.ItemTemplate>
    <DataTemplate>
      <view:NameView />
    </DataTemplate>
  </ItemsControl.ItemTemplate>
</ItemsControl>

每个的 DataContext 属性都是字符串类型(直接绑定到模型)，但是如果我希望 DataContext 绑定到基于该属性的 ViewModel 该怎么办.我将如何实例化 ViewModel 并将其提供给模型(字符串).

The DataContext property of each is of type string (bound directly to the Model), but what if I wanted the DataContext's to be bound to a ViewModel which is based on the property. How would I go about instantiating the ViewModel and feeding it the Model (string).

我希望这是有道理的.

推荐答案

为什么不做以下事情?

public ObservableCollection<NameViewModel> Names { get; set; }

这似乎有点奇怪，但 AFAIK 并没有具体禁止一个 VM 了解其他 VM.

This seems a bit odd, but AFAIK there isn't a specific prohibition against one VM knowing about others.

如果您将 DI 用于 VM 分辨率，显然您的设计必须进行调整.例如，您可以创建一个 NamesView，它是一个具有 IEnumerable 类型的公共 DependencyProperty 的 UserControl.然后，NamesView 的 ViewModel 绑定到这个 DP...

In a case where you use DI for VM resolution, obviously your design would have to be adjusted. For instance, you might create a NamesView which is a UserControl with a public DependencyProperty of type IEnumerable<string>. Then, the NamesView's ViewModel is bound to this DP...

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