Question

我希望获得NamePlaylist的{{1}}我点击MenuContext。但是参数总是空的我不知道为什么。

这是ListView中的菜单

XML

Item

一个CommandProvider

<MenuItem Header="Add" ItemsSource="{Binding Path=ItemSourcePlaylist}">
   <i:Interaction.Triggers>
      <i:EventTrigger EventName="Click">
         <i:InvokeCommandAction Command="{Binding TestCall}" CommandParameter="{Binding NamePlaylist}"/>
      </i:EventTrigger>
   </i:Interaction.Triggers>
   <MenuItem.ItemTemplate>
      <DataTemplate>
         <TextBlock Name="NamePlaylistText" Text="{Binding Path=NamePlaylist}"/>
      </DataTemplate>
   </MenuItem.ItemTemplate>
</MenuItem>

拨打

public class CommandProvider : ICommand
    {
    #region Constructors       

    public CommandProvider(Action<object> execute) : this(execute, null) { }

    public CommandProvider(Action<object> execute, Predicate<object> canExecute)
    {
        _execute = execute;
        _canExecute = canExecute;
    }

    #endregion

    #region ICommand Members

    public event EventHandler CanExecuteChanged;

    public bool CanExecute(object parameter)
    {
        return _canExecute != null ? _canExecute(parameter) : true;
    }

    public void Execute(object parameter)
    {
        if (_execute != null)
            _execute(parameter);
    }

    public void OnCanExecuteChanged()
    {
        CanExecuteChanged(this, EventArgs.Empty);
    }

    #endregion

    private readonly Action<object> _execute = null;
    private readonly Predicate<object> _canExecute = null;
    }

功能

public ICommand TestCall { get { return new RelayCommand(obj => this._settingsFunction.TestFunction(obj)); } }

Answer 1

如果我了解您的视图模型，则ItemSourcePlaylist和TestCall位于一个类中，NamePlaylist是ItemSourcePlaylist项的属性。如果是这种情况，我建议使用ItemsContainerStyle并将Command属性绑定到父级DataContext和CommandParameter到当前项DataContext

<MenuItem Header="Add" ItemsSource="{Binding Path=ItemSourcePlaylist}">
   <MenuItem.ItemContainerStyle>
       <Style TargetType="{x:Type MenuItem}">
           <Setter Property="Command" Value="{Binding RelativeSource={RelativeSource AncestorType={x:Type MenuItem}}, Path=DataContext.TestCall}"/>
           <Setter Property="CommandParameter" Value="{Binding NamePlaylist}"/>
       </Style>
   </MenuItem.ItemContainerStyle>
   <MenuItem.ItemTemplate>
       <DataTemplate>
           <TextBlock Name="NamePlaylistText"  Text="{Binding Path=NamePlaylist}"/>
       </DataTemplate>
   </MenuItem.ItemTemplate>
</MenuItem>

CommandParameter总是清空wpf MVVM

1 个答案: