Question

I am using WPF DataGrid and I would like to allow the user to select an entire column by clicking on the column header. I currently have the SelectionUnit set to CellOrRowHeader because I want the same functionality for rows (which works great). Is there an easy way to also allow selection of columns by clicking the column header?

Answer 1

You have many options. one is create your own Template for DataGrid’s Header Style. Inside the DataTemplate tag you can change the template of the headers. (you can replace the Button with a TextBlock or anything you want.)

<DataGrid>
    <DataGrid.ColumnHeaderStyle>
        <Style TargetType="DataGridColumnHeader" >
            <Setter Property="Foreground" Value="Blue" />
            <Setter Property="ContentTemplate" >
                <Setter.Value>
                    <DataTemplate>
                        <Button Content={Binding Content}" MouseDown="mouseDownEventHandler">
                    </DataTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </DataGrid.ColumnHeaderStyle>
</DataGrid>

or if you are using DataGrid.Columns to populate your columns and you need to set each of them separately, you can use this:

<DataGrid>
    <DataGrid.Columns>
        <DataGridTextColumn HeaderTemplate="{StaticResource MyTemplate1"/>
        <DataGridHyperlinkColumn HeaderTemplate="{StaticResource MyTemplate2"/>
    </DataGrid.Columns>
</DatGrid>

where MyTemplate1 and 2 should be defined previously in your control’s Resources.

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Edit:

The other approach according to this link is to add a PreviewMouseDown to your DataGrid and then find out if the mouse down was happend on the header or not.

This is the simple version of her event handler:

DependencyObject dep = (DependencyObject)e.OriginalSource;
while ((dep != null) && !(dep is DataGridColumnHeader))
{
    dep = VisualTreeHelper.GetParent(dep);
}
if (dep == null) return;
if (dep is DataGridColumnHeader)
{
    MessageBox.Show(((DataGridColumnHeader)dep).Content.ToString());
}