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How to: Implement Custom Grouping

  • 3 min to read

This example demonstrates how to implement custom grouping. The data is grouped by the 'Unit Price' column, and the column's rows that have values between 0 and 10 are combined into a single group. Rows whose values fall between 10 and 20 are combined into another group, etc.

The 'Unit Price' column's GridDataColumnSettings.SortMode property is set to 'Custom', and the ASPxGridView.CustomColumnGroup and ASPxGridView.CustomColumnSort events are handled identically.

Additionally, the ASPxGridView.CustomGroupDisplayText event is handled to replace the default text displayed within group rows.

The image below shows the result.

CustomColumnGroup

Note

Refer to the How to implement custom grouping logic for ASPxGridView columns online example to review how it works.

<dx:ASPxGridView ID="ASPxGridView1" runat="server" AutoGenerateColumns="False" 
    DataSourceID="AccessDataSource1" KeyFieldName="ProductID" 
    OnCustomColumnGroup="ASPxGridView1_CustomColumnGroup" 
    OnCustomColumnSort="ASPxGridView1_CustomColumnSort" 
    OnCustomGroupDisplayText="ASPxGridView1_CustomGroupDisplayText">

    <GroupSummary>
        <dx:ASPxSummaryItem SummaryType="Count" />
    </GroupSummary>

    <Columns>
        <dx:GridViewDataTextColumn FieldName="ProductID" ReadOnly="True" 
            VisibleIndex="0">
            <EditFormSettings Visible="False" />
        </dx:GridViewDataTextColumn>
        <dx:GridViewDataTextColumn FieldName="ProductName" VisibleIndex="1">
        </dx:GridViewDataTextColumn>

        <dx:GridViewDataTextColumn FieldName="UnitPrice" VisibleIndex="2" 
            GroupIndex="0" SortIndex="0" SortOrder="Ascending">
            <PropertiesTextEdit DisplayFormatString="c">
            </PropertiesTextEdit>
            <Settings AllowDragDrop="False" SortMode="Custom" />
        </dx:GridViewDataTextColumn>

        <dx:GridViewDataCheckColumn FieldName="Discontinued" VisibleIndex="3">
        </dx:GridViewDataCheckColumn>
    </Columns>

    <Settings ShowGroupedColumns="True" ShowGroupPanel="True" />
</dx:ASPxGridView>
protected void ASPxGridView1_CustomColumnSort(object sender, DevExpress.Web.ASPxGridView.CustomColumnSortEventArgs e){
    CompareColumnValues(e);
}

protected void ASPxGridView1_CustomColumnGroup(object sender, DevExpress.Web.ASPxGridView.CustomColumnSortEventArgs e){
    CompareColumnValues(e);
}

private void CompareColumnValues(DevExpress.Web.ASPxGridView.CustomColumnSortEventArgs e) {
    if (e.Column.FieldName == "UnitPrice"){
        int res = 0;

        double x = Math.Floor(Convert.ToDouble(e.Value1) / 10);
        double y = Math.Floor(Convert.ToDouble(e.Value2) / 10);
        res = Comparer.Default.Compare(x, y);
        if (res < 0) res = -1;
        else if (res > 0) res = 1;
        if (res == 0 || (x > 9 && y > 9)) res = 0;

        e.Result = res;
        e.Handled = true;
    }
}

protected void ASPxGridView1_CustomGroupDisplayText(object sender, DevExpress.Web.ASPxGridView.ASPxGridViewColumnDisplayTextEventArgs e){
    if (e.Column.FieldName == "UnitPrice"){
        double d = Math.Floor(Convert.ToDouble(e.Value) / 10);
        string displayText = string.Format("{0:c} - {1:c} ", d * 10, (d + 1) * 10);
        if (d > 9) displayText = string.Format(">= {0:c} ", 100);
        e.DisplayText = displayText;
    }
}