c# - 如何在 viewmodel 中访问 mvvm 模型中的控件？

Question

我有一个 WPF 窗口，在那个窗口中我有一个网格。

我使用 MV-VM 模型，我想在代码中动态地将 TextBox 添加到网格中（在 viewmodel 中）

如何访问网格？

Answer 1

使用监督控制器模式。

阅读：

此处显示了CaliburnMicro MVVM 框架的示例实现（对所有其他框架都一样 - 或者如果您自己执行 MVVM，您可以手动执行）：

http://drc.ideablade.com/devforce-2012/bin/view/Documentation/cocktail-tutorial-talk-to-view

例子：

1)定义接口IView，ViewModel( VM) 将在其中View与所需的方法进行对话

public interface IView 
{
    void AddTextBoxToGrid();
}

2）从你的和实现方法继承代码ViewIViewIView.AddTextboxToGrid()

public partial class View: IView 
{
    public void AddTextBoxToGrid() 
    {  
        // implement here your custom view logic using standard code behind; 
    }
}

3）将类型的属性添加IView到您的VM

public class ViewModel 
{
    public IView View { get; set; }
}

4)将View属性VMView设置为as的实例，IView 例如在后面的代码中：

 DataContext.View = this as IView; 

或在 Caliburn 中，您可以使用 IScreen.OnViewAttached 覆盖方法）

public partial class View: IView 
{
    public View()
    {
        // access you VM by the strategy of your framework or choice - this example is when you store your VM in View's DataContext
        (DataContext as ViewModel).View = this as IView;
    } 

    public void AddTextBoxToGrid() 
    {  
        // implement here your custom view logic using standard code behind; 
    }
}

5) In your VM call IView.AddTextboxToGrid()

public class ViewModel 
{
    public IView View { get; set; }

    public void AddTextBoxToGrid() 
    {
        if (View == null) return;
        View.AddTextBoxToGrid()
    }
}

Answer 2

您应该将创建代码移至 View，并且 ViewModel 应该在应该调用它时通知视图。

Answer 3

您还可以在视图后面的代码中使用视图的 DataContext（即 ViewModel），并将文本框添加到那里的网格中。那会更有意义。

如果您在 XAML 文件中为网格命名，您将能够立即在后面的代码中访问网格。

Answer 4

If you are using Caliburn Micro, implement following step:

1. Make the ViewModel inherited from interface IViewAware; you are going to implement two methods AttachView and GetView of this interface.

2. Define a variable with type of View to get the reference to the View

3. See detail below:

   private SomeViewClass v;
   public void AttachView(object view, object context = null)
   {
       v = view as BomView;
       if (ViewAttached != null)
            ViewAttached(this,
            new ViewAttachedEventArgs() { Context = context, View = view });
   }
   
   public object GetView(object context = null)
   {
       return v;
   }
   

Later on you can access a single element on the View through v such as v.txtName="John"; etc...