多绑定命令参数

Question

所以我有一个上下文菜单为每个单独的listview项目和listview绑定到一个用户列表。上下文菜单有一个子菜单，该子菜单绑定到一个可观察的用户状态集合。我希望能够从列表视图传递用户id和从上下文菜单到我的更新命令参数的新状态id。我刚刚研究了多重绑定，并相信这可能是一个很好的长期解决方案，我可以在其他地方使用。下面是一些代码:

ListView from User View:

<ListView Background="Transparent" ItemsSource="{Binding UserList}" SelectionMode="Single">
    <ListView.Resources>
        <ContextMenu x:Key="Menu" DataContext="{Binding Path=PlacementTarget.DataContext, RelativeSource={RelativeSource Self}}">
            <MenuItem Name="UserID" Header="{Binding UserID}"/>
                <Separator></Separator>
                    <MenuItem Header="Status" ItemsSource="{Binding DataContext.UserStatus, RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}}"
                              DisplayMemberPath="Name" Name="StatusID">
                        <MenuItem.ItemContainerStyle>
                            <Style TargetType="MenuItem">
                                <Setter Property="Command" Value="{Binding DataContext.UpdateDriverStatus, RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}}" />
                                <Setter Property="CommandParameter" Value="{Binding}" />
                            </Style>
                        </MenuItem.ItemContainerStyle>
                        <MenuItem.CommandParameter>
                            <MultiBinding Converter="{StaticResource MultiBindConverter}">
                                <Binding ElementName="DriverID"></Binding>
                                <Binding ElementName="StatusID"></Binding>
                            </MultiBinding>
                        </MenuItem.CommandParameter>                        </MenuItem>
                </ContextMenu>
            </ListView.Resources>
            <ListView.ItemContainerStyle>
                <Style TargetType="{x:Type ListViewItem}">
                    <Setter Property="ContextMenu" Value="{StaticResource Menu}" />
                </Style>
            </ListView.ItemContainerStyle>
            <ListView.ItemTemplate>
                <ItemContainerTemplate>
                            <TextBlock Text="{Binding UserName}" >
                            </TextBlock>
                </ItemContainerTemplate>
            </ListView.ItemTemplate>
        </ListView>

用户虚拟机:

public class UsersPanelVM : ViewModelBase, INotifyPropertyChanged
{
    public ObservableCollection<UserPanelItem> UserList { get; set; }
    public ObservableCollection<UserStatusList> UserStatus { get; set; }
    private readonly IUserService _userService;
    public IUserService UserService { get { return this._userService; } }
    public UsersPanelVM(IUserService userService)
    {
        this._userService = userService;
        var model = this.UserService.GetUsers();
        this.UserList = model.Users;
        var statusmodel = this.UserService.GetUserStatus();
        this.UserStatus = statusmodel.UserStatus;
        this.UpdateUserStatus = new RelayCommand<UserStatusList>((s) => UpdateStatus(1,s));
    }
    //The 1, above, is hard coded to test the method call, but ideally that should be the selected UserID
    private void UpdateStatus(int ID, UserStatusList s)
    {
    }
    public RelayCommand<UserStatusList> UpdateUserStatus { get; private set; }
}

Answer 1

1. 这是没有必要的，因为我已经在你的其他问题中提到过，因为你有所有的信息，除了新的状态在你的对象模型。

   将命令和UpdateStatus方法移动到UserPanelItem的类中，该类也应该包含您的ID，然后您只需将命令更改为:

   new RelayCommand(param => UpdateStatus(ID, (UserStatusList)param))
   

2. 如果你真的想这样做:你再次设置父MenuItem的CommandParameter，其命令永远不会被使用，将其移动到CommandParameter - Setter的Value的容器样式，即

   <Setter Property="CommandParameter">
       <Setter.Value>
           <MultiBinding ...>
               ....