清除并重新填充绑定的组合框

Question

我有一个WPF应用程序,其中包含许多组合在一起的组合框.当我切换组合框#1,组合框#2开关等.

这是2个组合框的xaml:

<ComboBox Grid.Row="1" Height="23" HorizontalAlignment="Right" Margin="0,12,286,0" ItemsSource="{Binding}" Name="CboDivision" VerticalAlignment="Top" Width="120" SelectionChanged="CboDivision_SelectionChanged" />
<ComboBox Height="23" HorizontalAlignment="Right" Margin="0,9,32,0" Name="CboCustomerList" ItemsSource="{Binding}" VerticalAlignment="Top" Width="120" SelectionChanged="CboCustomerList_SelectionChanged" Grid.Row="1" />

CboDivision在开始时填充,不需要重置.HEre是调用除法中的更改的代码,它应该触发客户的更改:

private void CboDivision_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    division = CboDivision.SelectedValue.ToString();
    CboCustomerList.ItemsSource = null;

    BackgroundWorker customerWorker = new BackgroundWorker();
    customerWorker.DoWork += new DoWorkEventHandler(FillCustomers);
    customerWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(customerWorker_RunWorkerCompleted);
    FillCustomers(null, null);

}

当我进行索引更改时,它会调用一个调用以下代码的backgroundworker:

    private void FillCustomers(object sender, DoWorkEventArgs e)
    {
        string connectionString = Settings.Default.ProdConnectionString;
        SqlConnection connection = new SqlConnection(connectionString);
        SqlCommand SqlCmd = new SqlCommand();
        Mouse.OverrideCursor = System.Windows.Input.Cursors.Wait;


            SqlCmd.CommandType = CommandType.StoredProcedure;
            SqlCmd.Parameters.Add("@division", SqlDbType.NVarChar).Value = division;
            SqlCmd.Connection = connection;
            SqlCmd.CommandText = "sp_GetCustomers";
            SqlDataReader reader = null;
            connection.Open();
            reader = SqlCmd.ExecuteReader();
            List<string> result = new List<string>();
            while (reader.Read())
            {
                result.Add(reader["NAME"].ToString());
            }
            e.Result = result;


   }

问题是我无法在CboDivision上切换选择并清除CboCustomerList并将新值重新加载到其中.这是我绑定xaml中的值的方式吗？如何更改CboDivision导致清除CboCustomerList项,然后执行填充例程？

我目前正在重置组合框:

CboCustomerList.SelectedIndex = -1;

但这只是将新的cbocustomerlist查询附加到最后我也试过了

CboCustomerList.Items.Clear()

但是在重新填充框并且用户选择一个项目之后,它只返回一个空引用错误.

Answer 1

好吧，您没有发布所有代码，但一个问题是您没有调用工作线程。

FillCustomers(null, null)用。。。来代替customerWorker.RunWorkerAsync()。

private void CboDivision_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    division = CboDivision.SelectedValue.ToString();
    CboCustomerList.ItemsSource = null;

    BackgroundWorker customerWorker = new BackgroundWorker();
    customerWorker.DoWork += new DoWorkEventHandler(FillCustomers);
    customerWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(customerWorker_RunWorkerCompleted);
    customerWorker.RunWorkerAsync(); // <-- this
}

让我知道这是否有帮助。如果还有更多问题，请发布其余的代码。