如何从后面的代码访问ViewModel [英] How can I access my ViewModel from code behind

问题描述

我不明白如何创建创建MVVM可点击矩形的命令.这是我的代码:

I don't understand how I can create a command to create a MVVM clickable rectangle. Here is my code:

<Rectangle x:Name="Color01" Fill="#FFF4F4F5" HorizontalAlignment="Left" Height="100" Margin="10,29,0,0" Stroke="Black" VerticalAlignment="Top" Width="100" MouseDown="Color_MouseDown" />
<Rectangle x:Name="Color02" Fill="#FFF4F4F5" HorizontalAlignment="Left" Height="100" Margin="115,29,0,0" Stroke="Black" VerticalAlignment="Top" Width="100"/>
<Rectangle x:Name="Color03" Fill="#FFF4F4F5" HorizontalAlignment="Left" Height="100" Margin="220,29,0,0" Stroke="Black" VerticalAlignment="Top" Width="100"/>
<Rectangle x:Name="Color04" Fill="#FFF4F4F5" HorizontalAlignment="Left" Height="100" Margin="325,29,0,0" Stroke="Black" VerticalAlignment="Top" Width="100"/>

在我的第一个矩形上，您可以看到我在事件背后创建了代码.首先，我不知道如何从后面的代码访问ViewModel.两个不是真正的MVVM.

On my first rectangle you can see I created a code behind event. First I don't know how to access my ViewModel from the code behind. Two it's not really MVVM.

public partial class MainWindow : Window
{
    /// <summary>
    /// Initializes a new instance of the MainWindow class.
    /// </summary>
    public MainWindow()
    {
        InitializeComponent();
        Closing += (s, e) => ViewModelLocator.Cleanup();
    }

    private void Color_MouseDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
    {
        // So what ???
    }
}

当有人单击我的矩形时，我只需要能够更改存储在viewModel中的列表中的简单布尔值.为什么与MVVM如此复杂?

I just need to be able to change a simple boolean value stored in a list stored in my viewModel when someone click on my rectangle. Why it is so complicate to do with MVVM?

推荐答案

这不太困难.首先，在Window XAML中创建ViewModel的实例:

This isn't too difficult. First, create an instance of your ViewModel inside your Window XAML:

查看XAML:

<Window  x:Class="BuildAssistantUI.BuildAssistantWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
     xmlns:VM="clr-namespace:MySolutiom.ViewModels">
     <Window.DataContext>
         <VM:MainViewModel />
     </Window.DataContext>
  </Window>

此后，您可以

After that, you can System.Windows.Interactivity.InvokeCommandAction to translate your event to a command:

查看XAML:

<Grid>
 <Rectangle x:Name="Color01" Fill="#FFF4F4F5" HorizontalAlignment="Left" Height="100" Margin="10,29,0,0" Stroke="Black" VerticalAlignment="Top" Width="100" MouseDown="Color_MouseDown">          <interactivity:Interaction.Triggers>
      <interactivity:EventTrigger EventName="MouseDown">
          <interactivity:InvokeCommandAction Command="{Binding MyCommand}"/>
      </interactivity:EventTrigger>
   </interactivity:Interaction.Triggers>
 </Rectangle>
</Grid>

现在，在您的ViewModel中，设置一个 ICommand 和 DelegateCommand 绑定到该事件的实现:

Now, in your ViewModel, set up an ICommand and the DelegateCommand implementation to bind to that event:

ViewModel:

public class ViewModel
{
    public ICommand MyCommand { get; set; }

    public ViewModel()
    {
        MyCommand = new DelegateCommand(OnRectangleClicked);
    }

    public void OnRectangleClicked()
    {
        // Change boolean here
    }
}

这篇关于如何从后面的代码访问ViewModel的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！