Question

我为它创建了一个line=$(awk -f '/nel/{print NR}' FILENAME} echo "$line"和绑定系统枚举值。并且还为它创建了一个值转换器，使其更具人性化。但是当我在ComboBox中选择项目时，它会显示错误并在控制台中转储一些错误消息知道怎么解决这个问题吗？我还尝试为ComboBox设置另一个值转换器，但它也不起作用。

cs文件：

SelectedItem

xaml文件：

using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO.Ports;
using System.Linq;
using System.Windows;
using System.Windows.Data;

namespace WpfApp1
{
    public partial class MainWindow : Window
    {
        private StopBits _stopBits;

        public StopBits SelectedStopBits
        {
            get { return _stopBits; }
            set { _stopBits = value; }
        }

        public MainWindow()
        {
            InitializeComponent();
            DataContext = this;
        }
    }

    public class DataConvert : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            var tmp = (int[])value;
            var convert = new Dictionary<StopBits, string>()
            {
                {StopBits.None, "none"},
                {StopBits.One, "1 bit"},
                {StopBits.Two, "2 bit"},
                {StopBits.OnePointFive, "1.5 bit"}
            };

            return tmp.Select(item => convert[(StopBits)item]).ToList();
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return value;
        }
    }
}

错误：

<Window x:Class="WpfApp1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp1"
        xmlns:serialPort="clr-namespace:System.IO.Ports;assembly=System"
        xmlns:provider="clr-namespace:System;assembly=mscorlib"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <ObjectDataProvider x:Key="StopBitsProvider" MethodName="GetValues" ObjectType="{x:Type provider:Enum}">
            <ObjectDataProvider.MethodParameters>
                <x:Type TypeName="serialPort:StopBits"/>
            </ObjectDataProvider.MethodParameters>
        </ObjectDataProvider>
        <local:DataConvert x:Key="DataConverter"/>
    </Window.Resources>
    <StackPanel>
        <TextBlock Text="Stop Bits:"/>
        <ComboBox ItemsSource="{Binding Source={StaticResource StopBitsProvider}, Converter={StaticResource DataConverter}}"
                  SelectedItem="{Binding SelectedStopBits}"/>
    </StackPanel>
</Window>

Answer 1

您需要将SelectedItem从string转换为StopBits值。

因此，应用于ConvertBack绑定的转换器的SelectedItem方法应返回一个枚举值，该属性实际上可以设置为：

public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
    StopBits enumValue = default(StopBits);
    if (value != null)
        Enum.TryParse(value.ToString(), out enumValue);

    return enumValue;
}

您无法将StopBits属性设置为string。

编辑或者你可以从转换器中返回字典：

public class DataConvert : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var tmp = (int[])value;
        var convert = new Dictionary<StopBits, string>()
        {
            {StopBits.None, "none"},
            {StopBits.One, "1 bit"},
            {StopBits.Two, "2 bit"},
            {StopBits.OnePointFive, "1.5 bit"}
        };

        return convert;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return value;
    }
}

...并稍微修改你的XAML：

<ComboBox ItemsSource="{Binding Source={StaticResource StopBitsProvider}, Converter={StaticResource DataConverter}}"
          SelectedValuePath="Key"
          DisplayMemberPath="Value"
          SelectedValue="{Binding SelectedStopBits}"/>

具有枚举转换失败的IValueConverter

1 个答案: