How to hide automatically generated columns in DataGrid?

Question

I've automatically populated a DataGrid from a DataTable from a SQL server. I want the user to be able to add or remove which columns are visible. I originally tried this:

    public void populateTaskTable(DataTable dt)
    {                    
        //add the whole datatable to the datagrid
        dg.DataContext = dt.DefaultView;

        dg.Columns[0].Visibility = Visibility.Collapsed;
    }

For a corresponding xaml (I've tried both with and without the AutoGenerateColumns="True"

           <DataGrid Name="dg" ItemsSource="{Binding}" AutoGenerateColumns="True" 

                    <!-- <DataGrid.Columns></DataGrid.Columns> -->

            </DataGrid>

Which resulted in a memory violation break. So then I did

MessageBox.Show(dg.Columns.Count());

to see if Columns was being populated, which it wasn't, it output a 0 even though I could see the columns in the program.

I found out from this previous stackoverflow question that "automatically generated columns are not added to the Columns index".

Then from this question I tried updating the DataGrid to get Columns populated like so

   taskTable.UpdateLayout();

and

   taskTable.Items.Refresh();

Which didn't do anything.

Is there a way to access the properties of an automatically generated DataGrid, or a way to add all of the columns of the DataGrid to the Columns component?

Thanks in advance.

Answer 1

Hook up the AutoGeneratingColumn event and hide the column over there.

dataGrid.AutoGeneratingColumn += dataGrid_AutoGeneratingColumn;

void dataGrid_AutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
{
    e.Column.Visibility = Visibility.Collapsed;
}

You may need to conditionally hide the columns, you can use

private void DataGrid_OnAutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
{
    if (e.PropertyName == "YourProperty")
    {
        e.Column.Visibility = Visibility.Collapsed;
    }
}

Or you can use AutoGeneratedColumns event. It will be fired when all the columns has been generated.

dataGrid.AutoGeneratedColumns += DataGrid1_AutoGeneratedColumns;

void DataGrid1_AutoGeneratedColumns(object sender, EventArgs e)
{
     int columnsCount = DataGrid1.Columns.Count;
     //You can access the columns here.
}

The link you referred says that Automatically generated columns are not added to the Columns collection. I just noticed that Auto generated columns are indeed added to the collection. It is poor answer that links to the documentation of System.Web.UI.WebControls.DataGrid which is very wrong.