Question

I have a DataGrid bound to a DataTable. I want the DataGrid to always have at least ten (empty) rows, also if there are not enough real data-items (the data comes in little by little).

One approach would be to easily add ten empty rows to the DataTable at initialization. But when a real data-item comes in, I can’t easily add the row, I have to find the first empty row to overwrite it, what is not very handy.
So someone knows a smarter/built-in way to achieve this?

Answer 1

It’s gonna be mess, no matter from what side it’s approached. I’d say your best bet (provided that your grid cells content won’t be wrapped) is to use a visual brush (with lines) as your DataGrid’s background.

UPDATE 1 – XAML
It’s alwast there, the trick is to use MinHeight, which will produce a vision of blank items thanks to tiled background. If your grid will be populated with the real data the background will expand, rendering more lines.

One thing I didn’t try is how it’ll handling scrolling.

Here’s an example:

<Grid>
    <Grid.Resources>
        <VisualBrush x:Key="StripesBrush" TileMode="Tile" Viewport="0,0,5,20"
               Viewbox="0,0,10,10" ViewportUnits="Absolute" 
               ViewboxUnits="Absolute">
            <VisualBrush.Visual>
                <Line X1="0" X2="10000" Y1="0" Y2="0" Stroke="DarkGray"/>
            </VisualBrush.Visual>
        </VisualBrush>
    </Grid.Resources>
    <DataGrid x:Name="g" AutoGenerateColumns="False" 
              GridLinesVisibility="None" 
              MinHeight="100"
              Height="100"
              VerticalAlignment="Top"
              Background="{StaticResource StripesBrush}">

        <DataGrid.Columns>
            <DataGridTextColumn Header="A" Width="Auto" Binding="{Binding Item1}">
                <DataGridTextColumn.CellStyle>
                    <Style TargetType="DataGridCell">
                        <Setter Property="Background" Value="Transparent"></Setter>
                    </Style>
                </DataGridTextColumn.CellStyle>
            </DataGridTextColumn>
            <DataGridTextColumn Header="B" Width="Auto" Binding="{Binding Item2}" />
        </DataGrid.Columns>
    </DataGrid>
</Grid>