WPF Combox 数据已更新但 UI 未更新 - 更新代码 [英] WPF Combox data updated but UI not updated - Updated code

问题描述

代码如下:

MainWindow.xaml

<ComboBox Grid.Column="1" Margin="2" VerticalContentAlignment="Center" ItemsSource="{Binding Path=LowDLane, Mode=OneWay}"
                                  SelectedIndex="{Binding Path=CurrentLowDLaneIndex, Mode=TwoWay, FallbackValue=0}"
                                  DropDownOpened="onLowDLaneDropDownOpened"
                                  SelectionChanged="onLowDLaneChanged">
</ComboBox>

MainWindow.xaml.cs

public partial class MainWindow : Window
{

    public MainWindow(ViewModel model)
    {
        InitializeComponent();
        this.DataContext = model;
    }

    private void onLowDLaneDropDownOpened(object aSender, EventArgs aE)
    {
        ((ViewModel)this.DataContext).openedDropDown();
    }
}

ViewModel.cs 更新

public class ViewModel : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChangedHandler;

    public List<string> LowDLane
    {
        get { return mLowDLane; }
        set
        {
            mLowDLane = value;
           PropertyChangedHandler.raise(this, ()=> LowDLane);
        }
    }
    public void openedDropDown()
    {
        LowDLane = new List<string> { "1", "2", "3", "4", "5", "6", "7", "8"};
    }

}

在其他文件中定义了 PropertyChangedEventHandler:

In other file PropertyChangedEventHandler is defined:

namespace System.ComponentModel

{

public delegate void PropertyChangedEventHandler(object sender, PropertyChangedEventArgs e);

}

表示将处理 System.ComponentModel.INotifyPropertyChanged.PropertyChanged 的​​方法更改组件上的属性时引发的事件.

Represents the method that will handle the System.ComponentModel.INotifyPropertyChanged.PropertyChanged event raised when a property is changed on a component.

PropertyChangedEventHandler 在其他地方运行良好，所以我不认为这是这里的问题.

PropertyChangedEventHandler works well in other places so I don't think this is the problem here.

我在其他文件中创建了 ViewModel 对象，并将其传递给 MainWindow.当我运行应用程序时，我可以看到 LowDLane 属性已更新，但 UI 未更新.

I created ViewModel object in other file, and passed it to MainWindow. When I run the application, I can see the LowDLane property is updated, but the UI is not updated.

我看过很多类似的问题，但没有一个能解决我的问题.有人可以帮忙吗?

I have looked many similar questions, but none of them solved my issue. Can someone help?

推荐答案

将 UpdateSourceTrigger 属性添加到组合框 itemSource 绑定并使 Mode 为 TwoWay.

Add UpdateSourceTrigger property to Combo box itemSource binding and make Mode to TwoWay.

ItemsSource="{Binding Path=LowDLane, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"

如果这能解决问题，请告诉我.

Let me know if this solves the issue.

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