传递给命令 WPF 的多个参数 [重复]

Question

我有以下层次结构：

abstract class TicketBase
{
    public DateTime PublishedDate { get; set; }
}

class TicketTypeA:TicketBase
{
     public string PropertyA { get; set; }
}   

class TicketTypeB:TicketBase
{
     public string PropertyB { get; set; }
}

在我的虚拟机中，我有一个List<TicketBase> Tickets。当用户单击我的应用程序上的按钮时，他们希望查看某个属性的 previous 值列表，例如：

<Button Tag="{x:Type Types:TicketTypeA}" 
        Command="{Binding ListHistoryCommand}"
        CommandParameter="{Binding Tag, RelativeSource={RelativeSource Self}}" />

如您所见，我将 Tag 属性设置为 TicketTypeA 并将其作为参数传递给我的命令：

private void ListHistory(object o)
{
   if (Tickets.Count == 0)
       return;
   Type ty = o as Type;
   ValueHistory = new ObservableCollection<TicketBase>(GetTicketsOfType(ty).Select(t => t)); // <- Need to return t.PropertyA here, but dynamically
}

IEnumerable<TicketBase> GetTicketsOfType(Type type)
{
    if (!typeof(TicketBase).IsAssignableFrom(type))
        throw new ArgumentException("Parameter 'type' is not a TicketBase");
    return Tickets.Where(p => p.GetType() == type);
}

（ValueHistory 是我在网格上设置为ItemsSource 的另一个集合）

但是我还需要传入 property 名称，这样我就可以像这样在网格中显示该属性：

Published Time     |  PropertyA
===================================================
09:00              | <value of PropertyA at 09:00>
08:55              | <value of PropertyA at 08:55>

所以问题基本上是将属性名称作为另一个参数传递给我的命令的最干净的方法是什么？

Answer 1

看到这个问题
Passing two command parameters using a WPF binding

更新
如果您需要在Button 上同时存储类型和属性名称，则必须使用您所说的附加属性。要将这两个参数传递给命令，这样的事情应该可以工作

<Button Tag="{x:Type Types:TicketTypeA}"
        local:ParameterNameBehavior.ParameterName="{Binding Source='Parameter A'}"
        Command="{Binding ListHistoryCommand}">
    <Button.CommandParameter>
        <MultiBinding Converter="{StaticResource PassThroughConverter}">
            <Binding Path="Tag" RelativeSource="{RelativeSource Self}"/>
            <Binding Path="(local:ParameterNameBehavior.ParameterName)"
                     RelativeSource="{RelativeSource Self}"/>
        </MultiBinding>
    </Button.CommandParameter>
</Button>

参数名称行为

public static class ParameterNameBehavior
{
    private static readonly DependencyProperty ParameterNameProperty = 
        DependencyProperty.RegisterAttached("ParameterName",
                                            typeof(string),
                                            typeof(ParameterNameBehavior));
    public static void SetParameterName(DependencyObject element, string value)
    {
        element.SetValue(ParameterNameProperty, value);
    }
    public static string GetParameterName(DependencyObject element)
    {
        return (string)element.GetValue(ParameterNameProperty);
    }
}

PassThroughConverter

public class PassThroughConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        return values.ToList();
    }
    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
        throw new NotSupportedException();
    }
}

Answer 2

我通过在 Xaml 中使用 x:Name 属性，然后将其作为 MultiBinding 与标记一起传递给我的 CommandParameter，无需借助附加属性即可完成这项工作。从前到后：

在我看来：

 <Button Content="{Binding PropertyA}" x:Name="PropertyA" Tag="{x:Type Types:TicketTypeA}" Style="{StaticResource LinkButton}"/>

 <Button Content="{Binding PropertyB}" x:Name="PropertyB" Tag="{x:Type Types:TicketTypeB}" Style="{StaticResource LinkButton}"/>

在每个按钮的样式中：

 <Style x:Key="LinkButton" TargetType="Button">
        <Setter Property="Command" Value="{Binding DataContext.ListHistoryCommand, Mode=OneWay, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}}" />

        <Setter Property="CommandParameter">
            <Setter.Value>
                <MultiBinding Converter="{StaticResource propertyConverter}">
                    <MultiBinding.Bindings>
                        <Binding Path="Tag" RelativeSource="{RelativeSource Mode=Self}"/>
                        <Binding Path="Name" RelativeSource="{RelativeSource Mode=Self}"/>
                    </MultiBinding.Bindings>
                </MultiBinding>
            </Setter.Value>
        </Setter>

在我的转换器中：

public class PropertyConverter : IMultiValueConverter
{
        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
        {
            //Type t = values[0] as Type;
            //String propName = values[1] as string;

            Type t = values[0] as Type;
            if (t == null)
                return typeof(TicketBase);
            String s = values[1] as String;

            return new Tuple<Type,String>(t,s);
        }
}

在我的视图模型中：

private void ListHistory(object o)
    {
        if (Tickets.Count == 0)
            return;
        var tuple = o as Tuple<Type,String>;

        // Now write some code to dynamically select the propertyName (tuple.Item2) from the type (tuple.Item1)  

    }

我现在在我的命令中收到类型和属性名称。现在，我只需要在运行时编译一个 lambda 表达式to dynamically Select the PropertyName from the Type。