Data Summaries in .NET MAUI Data Grid

• Oct 26, 2022
• 2 minutes to read

DataGridView can automatically calculate summaries for groups of rows or entire columns. For example, it can sum values, count the number of records, detect a minimum or maximum value, etc.

The grid supports two summary types:

Group Summary

An aggregate function value is calculated over all rows in a group and displayed in a group row.

Total Summary

An aggregate function value is calculated over all rows in a column and displayed below this column.

To create a total or group summary, add a GridColumnSummary object to the DataGridView.TotalSummaries or DataGridView.GroupSummaries collection, and adjust the following summary settings:

• FieldName—the field name of the column for which the summary is calculated.
• Type—the aggregate function used to calculate the summary value.
• DisplayFormat (optional)—the summary value format.

The grid supports five predefined summary aggregate functions:

• Count—the number of data rows.
• Max and Min—the maximum and minimum values.
• Sum and Average—the sum and average values.

You can also implement and apply a custom aggregate function. To do this, set the GridColumnSummary.Type property to Custom, and handle the DataGridView.CustomSummary event.

Example

The following example uses predefined aggregate functions (Max and Sum) and a custom rule to calculate group and total summaries for a grid that displays orders grouped by dates.

Set up the following summaries:

• A group summary to display the maximum Total value for each group of orders.
• A total summary to calculate the sum of values in the Total column.
• A custom total summary to count the number of orders with the false value in the Shipped column.

XAML

<dxg:DataGridView x:Name="grid" ItemsSource="{Binding Orders}" 
                  CustomSummary="grid_CalculateCustomSummary">
    <!-- ... -->
    <dxg:DataGridView.GroupSummaries>
        <dxg:GridColumnSummary FieldName="Total" Type="Max"/>
    </dxg:DataGridView.GroupSummaries>

    <dxg:DataGridView.TotalSummaries>
        <dxg:GridColumnSummary FieldName="Total" Type="Sum" 
                               DisplayFormat="Total: {0:C0}"/>
        <dxg:GridColumnSummary FieldName="Shipped" Type="Custom" 
                               DisplayFormat="Not Shipped: {0}"/>
    </dxg:DataGridView.TotalSummaries>
</dxg:DataGridView>

C#

int count;
// ...

void grid_CalculateCustomSummary(object sender, DevExpress.Data.CustomSummaryEventArgs e) {
    if (e.FieldName.ToString () == "Shipped")
        if (e.IsTotalSummary){
            if (e.SummaryProcess == CustomSummaryProcess.Start) {
                count = 0;
            }
            if (e.SummaryProcess == CustomSummaryProcess.Calculate) {
                if (!(bool)e.FieldValue)
                    count++;
                e.TotalValue = count;
            }
        }
}