Question

我有ListView我绑定到ObservableCollection，其泛型类型为MyCommand。当我更改MyCommand对象中的属性时，ListView不会更新。

转换器：

public class CommandToStringConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return value.ToString();
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

查看：

<ListView ItemsSource="{Binding Commands}">
    <ListView.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding Converter={StaticResource CommandToStringConverter}}"></TextBlock>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

查看CodeBehind：

public MainWindow()
{
    InitializeComponent();
    DataContext = new MainViewModel();
}

视图模型：

using Prism.Mvvm;

public class MainViewModel : BindableBase
{
    private ObservableCollection<MyCommand> _commands;
    public ObservableCollection<MyCommand> Commands
    {
        get { return _commands; }
        set { SetProperty(ref _commands, value); }
    }

    public MainViewModel()
    {
        //setup test data
        Commands = new ObservableCollection<MyCommand>(new [] {
            new MyCommand(
                CommandType.HotKey, 
                new [] {
                    new MyCommandBinding(HotKey.F5),
                    new MyCommandBinding(HotKey.F1)
                })
            });
    }        
}

型号：

public enum CommandType
{
    HotKey
}

public enum HotKey
{
    F1,
    F5,
    A,
    B,
    C
}

public class MyCommand : BindableBase
{
    private CommandType _commandType;
    public CommandType CommandType
    {
        get { return _commandType; }
        set { SetProperty(ref _commandType, value); }
    }

    private ObservableCollection<MyCommandBinding> _commandBindings;
    public ObservableCollection<MyCommandBinding> CommandBindings 
    {
        get { return _commandBindings; }
        set { SetProperty(ref _commandBindings, value); }
    }

    public MyCommand(CommandType commandType, IEnumerable<MyCommandBinding> bindings)
    {
        CommandType = commandType;
        CommandBindings = new ObservableCollection<MyCommandBinding>(bindings);
    }

    public override string ToString()
    {
        var text = string.Empty;
        foreach(var binding in CommandBindings)
        {
            if(!string.IsNullOrEmpty(text)) text += " + ";
            text += binding.HotKey.ToString();
        }
        return CommandType.ToString() + ", " + text;
    }  
}

public class MyCommandBinding : BindableBase
{
    private HotKey _hotKey;
    public HotKey HotKey
    {
        get { return _hotKey; }
        set { SetProperty(ref _hotKey, value); }
    }

    public MyCommandBinding(HotKey hotKey)
    {
        HotKey = hotKey;
    }
}

现在，当我更改属性Commands[0].CommandBindings[0].HotKey = HotKey.A;时，视图不会更新。

我错过了什么或做错了什么？

修改

我现在正在使用ItemTemplate和转换器，我仍然有相同的行为（初始帖子已更新）。如果我在转换器中调用ToString方法或者使用属性，我没有任何区别。就像Brian Lagunas指出的那样，如果我重新分配Commands列表，它会更新视图。

Answer 1

您似乎正在使用对象的ToString来表示ListView中对象的显示。在属性更改时不会重新查询ToString。

ListView绑定INotifyPropertyChanged无法正常工作

1 个答案: