WPF-MVVM中.NET(Rx)的反应性扩展 [英] Reactive Extensions for .NET (Rx) in WPF - MVVM

问题描述

我在WPF应用程序中使用带有Caliburn.Micro的NET(Rx)反应性扩展.我正在尝试将WPF应用程序移植为使用MVVM体系结构，并且需要监视TextBox控件的Text属性中的更改.

I am using Reactive extensions for NET (Rx) with Caliburn.Micro in my WPF app. I'm trying to port my WPF app to use an MVVM architecture and I need to monitor changes in the Text property of a TextBox control.

如果Text属性的最后一次更改超过3秒钟，则需要调用服务的LoadUser方法.

If the last change of the Text property was more than 3 seconds ago I need to call the LoadUser method of a service.

将逻辑从我的旧解决方案移植到具有MVVM架构的新解决方案.

Porting the logic from my old solution to the new solution with MVVM architecture.

XAML:

<TextBox Name="Nick" 
         Grid.Row="0"
         FontSize="14"
         Margin="2,2,2,2" 
         HorizontalAlignment="Stretch" 
         TextChanged="Nick_TextChanged" />

在后面的代码中，我有以下内容:

...

Observable.FromEvent<TextChangedEventArgs>(Nick, "TextChanged")
          .Select(e => ((TextBox)e.Sender).Text)
          .Where(text => text.Length > 3)               
          .Do(LoadUser)     
          .Throttle(TimeSpan.FromSeconds(3000))     
          .Subscribe(LoadUser);

...
private  void LoadUser(string text){...}

我想在我的视图模型类中使用Observable.FromEvent.像这样

I would like use Observable.FromEvent in my view model class. Something like this

查看:

<TextBox Name="Nick" 
         Grid.Row="0"
         FontSize="14"
         Margin="2,2,2,2" 
         HorizontalAlignment="Stretch"
         Micro:Message.Attach="[TextChanged]=[Action TextChanged()]"/>

查看模型:

[Export(typeof(IAddFriendViewModel))]
public class AddFriendViewModel : Screen, IAddFriendViewModel
{
    private string _nick;

    public string Nick
    {
        get { return _nick; }
        set
        {
            _nick = value;
            NotifyOfPropertyChange(()=>Nick);
        }
    }

    ...

    //how can I access to textbox control Nick in view from view model class?
    Observable.FromEvent<TextChangedEventArgs>(Nick, "TextChanged")
              .Select(e => ((TextBox)e.Sender).Text)
              .Where(text => text.Length > 3)
              .Do(LoadUser)
              .Throttle(TimeSpan.FromSeconds(3000))
              .Subscribe(LoadUser);
    ...

    private void LoadUser(string text)
    { }

    public void TextChanged()
    {
    }
}

我的问题是Observable.FromEvent使用TextBox控件，我不知道如何从ViewModel类访问此控件.

My problem is Observable.FromEvent uses the TextBox control and I don’t know how can I access this control from my ViewModel class.

我可以绑定到TextBox的Text属性，也可以将命令绑定到TextBox控件的某些事件，但是此方法使用View中的一个对象.

I can bind to the Text property of TextBox or I can bind a command to some event of the TextBox control, but this method uses an object in the View.

感谢创意.

推荐答案

将Nick属性添加到ViewModel并实现INotifyPropertyChanged.那你就可以做到

Add a Nick property to your ViewModel and implement INotifyPropertyChanged. Then you can do this

Observable.FromEventPattern<PropertyChangedEventArgs>(this, "PropertyChanged")
          .Where(e => e.EventArgs.PropertyName == "Nick")
          .Select(_ => this.Nick)
          .Where(text => text.Length > 3)
          //Subscribe will call LoadUser, no need for the extra Do(...)
          .Throttle(TimeSpan.FromSeconds(3000))
          .Subscribe(LoadUser);  

然后您的XAML就是这样

and then your XAML would be something like this

<TextBox Name="Nick" 
         Grid.Row="0"
         FontSize="14"
         Margin="2,2,2,2" 
         HorizontalAlignment="Stretch"
         Text="{Binding Nick, UpdateSourceTrigger=PropertyChanged}" />

这篇关于WPF-MVVM中.NET(Rx)的反应性扩展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！