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我正在嘗試從一個ComboBox數據綁定信息。我嘗試下面的代碼。如何獲取ComboBox.SelectionBoxItemProperty的數據綁定信息?
XAML:
<ComboBox Name="ddd" Margin="61,55,273,223" ItemsSource="{Binding myData, ElementName=window}" DisplayMemberPath="name" />
<TextBox Name="te" Height="30" TextChanged="TextBox_TextChanged" Margin="61,140,273,140" Text="{Binding SelectedItem.roll, ElementName=ddd}"/>
<Button Content="Button" Height="50" HorizontalAlignment="Left" Margin="268,120,0,0" Name="button1" VerticalAlignment="Top" Width="151" Click="button1_Click" />
C#代碼:
public partial class MainWindow : Window
{
public List<testData> myData { get; set; }
public MainWindow()
{
myData = new List<testData>();
InitializeComponent();
myData.Add(new testData { name = "a", roll = "1" });
myData.Add(new testData { name = "b", roll = "2" });
myData.Add(new testData { name = "c", roll = "3" });
this.DataContext = this;
}
private void button1_Click(object sender, RoutedEventArgs e)
{
var Be = this.ddd.GetBindingExpression(ComboBox.SelectionBoxItemProperty);
var data = (testData)Be.DataItem;
MessageBox.Show(data.roll);
}
}
public class testData
{
public string name { get; set; }
public string roll { get; set; }
}
但它拋出 「對象引用不設置到對象的實例」 這行例外
var data = (testData)Be.DataItem;
其中i做錯了 ?
thank`s尋求幫助。