Question

我有一个使用multibindings生成的运输标签，如下所示：

<TextBox x:Name="TextBoxShippingLabel" Margin="0,10,-2,2" TextWrapping="Wrap">
    <TextBox.Text>
        <MultiBinding StringFormat="{}{0} {1}&#x0a;{2}&#x0a;{3}&#x0a;{4}&#x0a;{5}&#x0a;{6} {7}">
            <Binding ElementName="dataGridOutstandingOrders" Path="SelectedItem[FirstName]" />
            <Binding ElementName="dataGridOutstandingOrders" Path="SelectedItem[Surname]" />
            <Binding ElementName="dataGridOutstandingOrders" Path="SelectedItem[Department]" />
            <Binding ElementName="dataGridOutstandingOrders" Path="SelectedItem[Organisation]" />
            <Binding ElementName="dataGridOutstandingOrders" Path="SelectedItem[Street]" />
            <Binding ElementName="dataGridOutstandingOrders" Path="SelectedItem[Suburb]" />
            <Binding ElementName="dataGridOutstandingOrders" Path="SelectedItem[State]" />
            <Binding ElementName="dataGridOutstandingOrders" Path="SelectedItem[Postcode]" />
        </MultiBinding>
    </TextBox.Text>
</TextBox>

这很有效，除非组织或部门等数据回复为“无”（在个人订单的情况下会发生）。当发生这种情况时，标签代表如下：

有没有办法可以使用XAML识别绑定何时返回“无”并使用备用StringFormat？

Answer 1

我遇到了同样的问题而且我使用了转换器。简单干净：

  <MultiBinding Converter="{StaticResource TextAlternateConverter}">

public class TextAlternateConverter: IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {

      StringBuilder myOutputText = new StringBuilder();

        foreach (string param in values)
        {
            if (param == "None")
                myOutputText.Append("Give alternate text");
            else
                myOutputText.Append(param);
        }

        return myOutputText.ToString();
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new System.NotImplementedException();
    }
}

Answer 2

我知道你要求没有代码隐藏的解决方案。但是我不认为这是可能的，因为你想要一些＆＃34; ifs＆＃34;在你的字符串格式内。这在后面的代码中也是不可能的（参见我提供的扩展方法）。

如果你可以扩展SelectedItem（无论可能是什么），我会在那里放置一个属性。这可能在将来有用（例如，通过API发送标签）。如果您无法访问代码库，也可以使用ExtensionMethod。

您至少有2个＆＃34;变通办法＆＃34;：

代码背后：

public partial class MainWindow
{
    public MainWindow()
    {
        this.InitializeComponent();

        List<OrderViewModel> newList = new List<OrderViewModel>();

        newList.Add(new OrderViewModel() { FirstName = "foo", LastName = "bar", Organization = "SO", ZipCode = "666" });
        newList.Add(new OrderViewModel() { LastName = "bar", Organization = "SO", ZipCode = "666" });
        newList.Add(new OrderViewModel() { FirstName = "foo", ZipCode = "666" });
        newList.Add(new OrderViewModel() { FirstName = "foo" });
        newList.Add(new OrderViewModel() { FirstName = "foo", LastName = "bar", Organization = "SO", ZipCode = "666" });

        DataContext = newList;
    }
}
public static class Extensions
{
    public static string GenerateShippingLabel(this OrderViewModel order)
    {
        StringBuilder sb = new StringBuilder();

        if (order.FirstName != "None")
        {
            sb.AppendFormat("{0} ", order.FirstName);
        }
        if (order.LastName != "None")
        {
            sb.AppendLine(order.LastName);
        }
        else
        {
            sb.AppendLine();
        }

        if (order.Organization != "None")
        {
            sb.AppendLine(order.Organization);
        }
        if (order.ZipCode != "None")
        {
            sb.AppendLine(order.ZipCode);
        }

        return sb.ToString();
    }
}

public class ShippingLabelConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is OrderViewModel)
        {
            return (value as OrderViewModel).GenerateShippingLabel();
        }
        return "None"; //isn't it ironic? ;-)
    }

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

public class OrderViewModel
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Organization { get; set; }
    public string ZipCode { get; set; }

    public string ShippingLabel
    {
        get
        {
            return this.GenerateShippingLabel();
        }
    }
}

<强> XAML

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition />
        <ColumnDefinition />
    </Grid.ColumnDefinitions>
    <ItemsControl ItemsSource="{Binding}">
        <ItemsControl.ItemTemplate>
            <DataTemplate>
                <TextBox Text="{Binding Path=ShippingLabel, Mode=OneWay}" />
            </DataTemplate>
        </ItemsControl.ItemTemplate>
    </ItemsControl>
    <ItemsControl ItemsSource="{Binding}" Grid.Column="2">
        <ItemsControl.Resources>
            <local:ShippingLabelConverter x:Key="labelConverter" />
        </ItemsControl.Resources>
        <ItemsControl.ItemTemplate>
            <DataTemplate>
                <TextBox Text="{Binding Converter={StaticResource labelConverter},Mode=OneWay}" />
            </DataTemplate>
        </ItemsControl.ItemTemplate>
    </ItemsControl>
</Grid>

不使用代码隐藏，从文本框中删除“无”

2 个答案: