為什么DataGrid中的AutoGeneratingColumn事件會重復這些列？

Question

當我在列表中搜索時，將結果傳遞給函數以加載DataGrid，每次觸發AutoGeneratingColumn事件時，它將再次重復同一列。 啟動應用程序時，事件將檢查該列一次，第一次搜索將檢查兩次，第二次則進行三次，依此類推。 我有下一個函數來加載DataGrid：

private void cargarListaAgenda(List<listaAgendaClass> lista)
{
    Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Background, new Action(() =>
    {
        gridAgendaDataGridAgenda.AutoGeneratingColumn += (s, e) =>
        {
            e.Column.Visibility = Visibility.Hidden;

            if (e.Column.Header.ToString() == "Nombre" || e.Column.Header.ToString() == "Alias" || e.Column.Header.ToString() == "Apellidos")
            {
                e.Column.Visibility = Visibility.Visible;

                if (e.Column.Header.ToString() != "Apellidos")
                    e.Column.Width = new DataGridLength(gridAgendaDataGridAgenda.Width * 0.33);

                else
                    e.Column.Width = new DataGridLength(1, DataGridLengthUnitType.Star);
            }
        };

        gridAgendaDataGridAgenda.ItemsSource = null;
        gridAgendaDataGridAgenda.ItemsSource = lista;
    }));
}

Answer 1

似乎每次調用cargarListaAgenda方法時都在附加一個新的事件處理程序。

嘗試在附加新事件處理程序之前將其刪除：

private void cargarListaAgenda(List<listaAgendaClass> lista)
{
    Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Background, new Action(() =>
    {
        gridAgendaDataGridAgenda.AutoGeneratingColumn -= GridAgendaDataGridAgenda_AutoGeneratingColumn;
        gridAgendaDataGridAgenda.AutoGeneratingColumn += GridAgendaDataGridAgenda_AutoGeneratingColumn;

        gridAgendaDataGridAgenda.ItemsSource = lista;
    }));
}

private void GridAgendaDataGridAgenda_AutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
{
    e.Column.Visibility = Visibility.Hidden;

    if (e.Column.Header.ToString() == "Nombre" || e.Column.Header.ToString() == "Alias" || e.Column.Header.ToString() == "Apellidos")
    {
        e.Column.Visibility = Visibility.Visible;

        if (e.Column.Header.ToString() != "Apellidos")
            e.Column.Width = new DataGridLength(gridAgendaDataGridAgenda.Width * 0.33);

        else
            e.Column.Width = new DataGridLength(1, DataGridLengthUnitType.Star);
    }
}