无法在按钮单击的列表框中添加项目

Question

我是 MVVM 的新手。我在主窗口内部有两个网格，其中一个网格包含左侧的列表框，右侧的另一个网格包含列表视图和 2 个按钮。

我能够将项目添加到列表视图，甚至可以弄清楚如何从列表视图中获取所选项目。一旦我在列表视图中选择了项目并单击按钮（连接），左侧的列表框就会更新为我从 viewmodel 类中添加的项目。

下面的视图显示了我左边的列表框：

<Grid Grid.Column="0" Name="BoardTabSelect" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
    <ListBox Name="ButtonPanel" 
             ItemsSource="{Binding BoardTabs, Mode=TwoWay}" 
             SelectedItem="{Binding SelectedTab, Mode=TwoWay}" >
        <ListBox.ItemTemplate>
            <DataTemplate>
                <StackPanel Orientation="Horizontal">
                    <TextBlock Name="BoardtabChanger" 
                               Margin="53,27,0,0" 
                               Text="{Binding TabOperation}" />
                </StackPanel>
            </DataTemplate>
        </ListBox.ItemTemplate>
    </ListBox>
</Grid>

下面的视图显示向右的列表视图以及 2 个按钮：

<Grid Grid.Row="0" Name="MainConnectGrid" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" >
    <ListView Name="listView" 
              ItemsSource="{Binding Products}" 
              SelectedItem="{Binding SelectedProduct, Mode=TwoWay}">
        <ListView.View>
            <GridView>
                <GridViewColumn Width="300" 
                                Header="Name" 
                                DisplayMemberBinding="{Binding Name}" />
                <GridViewColumn Width="283" 
                                Header="Connection Status" 
                                DisplayMemberBinding="{Binding Connection_Status}" />
            </GridView>
        </ListView.View>
    </ListView>

    <Button Content="Connect" 
            Height="23" Width="100" 
            HorizontalAlignment="Left" VerticalAlignment="Top"
            Margin="55,519,0,0" 
            Name="ConnectBtnGrid"  
            Command="{Binding Path=ConnectCommand}" />                        
    <Button Content="Disconnect" 
            Height="23" Width="100"
            HorizontalAlignment="Left" VerticalAlignment="Top" 
            Margin="446,519,0,0" 
            Name="DisconnectBtn" 
            Command="{Binding Path=DisconnectCommand}" />
</Grid>

查看模型：

public class ProductViewModel : INotifyPropertyChanged 
{
    public List<Product> m_Products;
    public List<Product> m_BoardTabs;                

    public ProductViewModel()
    {           
        m_Products = new List<Product>()
        {                
            new Product() {Name = "Bavaria", Connection_Status = "Disconnected"},
            new Product() {Name = "Redhook", Connection_Status = "Disconnected"},                
        };

        m_BoardTabs = new List<Product>()
        {
            new Product() {TabOperation = "Connect"}                 
        };
    }                      

    public List<Product> Products { get; set; }

    public List<Product> BoardTabs { get; set; }

    private Product m_SelectedItem;
    public Product SelectedProduct
    {
        get { return m_SelectedItem; }

        set
        {
            m_SelectedItem = value;                
            NotifyPropertyChanged("SelectedProduct");
        }
    }

    private Product m_SelectedTab;
    public Product SelectedTab
    {
        get { return m_SelectedTab; }

        set
        {
            m_SelectedTab = value;
            NotifyPropertyChanged("SelectedTab");                
        }
    }

    private ICommand mUpdater;
    public ICommand ConnectCommand
    {
        get
        {
            if (mUpdater == null)
                mUpdater = new DelegateCommand(new Action(SaveExecuted), new Func<bool>(SaveCanExecute));

            return mUpdater;
        }
        set { mUpdater = value; }
    }

    public bool SaveCanExecute()
    {
        return true;
    }     

    public void SaveExecuted()
    {
        if (SelectedProduct.Connection_Status == "Disconnected" && SelectedProduct.Name == "Bavaria")
        {
            SelectedProduct.Connection_Status = "Connected";
            m_BoardTabs.Add(new Product() { TabOperation = "I2C" });         
            m_BoardTabs.Add(new Product() { TabOperation = "Voltage" });    
            m_BoardTabs.Add(new Product() { TabOperation = "Codec" });   
        }
    }
}

在 Save Executed 方法中，我试图在列表框中添加项目，但是当我运行应用程序并从列表视图中选择项目并按 CONNECT Btn 时，列表不会更新。我的模型类包含所有三个属性（名称、连接状态和 TabOperation）

Answer 1

检查 ProductViewModel 的属性。它实现了 INotifyPropertyChanged ，并且在 Products、BoardTabs 中，您不会通知更改。

  public List<Product> Products
        {
            get
            {
                return m_Products;
            }

            set
            {
                m_Products = value;
NotifyPropertyChanged("Products")
            }
        }

        public List<Product> BoardTabs
        {
            get
            {
                return m_BoardTabs;
            }

            set
            {
                m_BoardTabs = value;
NotifyPropertyChanged("BoardTabs")
            }
        }

Answer 2

BoardTabs 和 Products 必须是 ObservableCollection<Product>。否则 WPF 不会收到有关列表中新项目的通知，因此无法更新 UI。