條件綁定？

Question

我正在嘗試將 TextBox 綁定到類集合中的值。 我該怎么做呢？

數據：

Name, Filter
A    , 1
B    , 2
C    , 3

現在我想用 Filter 填充我的 TextBlock，其中 Name = A。

XAML

<TextBlock Text="{Binding [Filters.??.Filter where name =??], UpdateSourceTrigger=PropertyChanged}"></TextBlock>

綁定到 ColumnFilter 列表

public class Model
{
    private ObservableCollection<DataGridColumnFilter> _filters = new ObservableCollection<DataGridColumnFilter>();
    public ObservableCollection<DataGridColumnFilter> Filters { get { return _filters; } set { _filters = value; } }
}
public class DataGridColumnFilter
{
    public string Name { get; set; }
    public string Filter { get; set; }
}

Answer 1

您應該使用轉換器：

<Page.Resources>
    <Samples:FilterConverter x:Key="FilterConverter"/>
</Page.Resources>

<Grid>
    <TextBox Text="{Binding Path=Filters, 
        Converter={StaticResource FilterConverter}, 
        ConverterParameter=a, Mode=OneWay}"/>
</Grid>


public class ConditionalBindingVM
{
    public ConditionalBindingVM()
    {
        Filters = new ObservableCollection<ColumnFilter>
                      {
                          new ColumnFilter {Name = "a", Filter = "filter A"},
                          new ColumnFilter {Name = "b", Filter = "filter B"},
                          new ColumnFilter {Name = "c", Filter = "filter C"},
                      };
    }

    public IEnumerable<ColumnFilter> Filters { get; private set; }
}

public class ColumnFilter
{
    public string Name { get; set; }
    public string Filter { get; set; }
}

public class FilterConverter : IValueConverter
{
    #region Implementation of IValueConverter

    public object Convert(object value, Type targetType, 
                          object parameter, CultureInfo culture)
    {
        var filters = (IEnumerable<ColumnFilter>) value;
        var name = (string) parameter;

        var filter = filters.SingleOrDefault(f => f.Name == name);

        return filter != null ? filter.Filter : string.Empty;
    }

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

    #endregion
}

Answer 2

使用 KeyUp 事件並執行此操作（使用 System.Linq）：

myTextBox.Text= Filters.FirstOrDefault(c=> c.Name.StartsWith(myTextBox.Text)).Filter;