GridViewDataColumn.GroupIndex Property

Gets or sets a value that specifies whether the column takes part in grouping and at which level.

Namespace: DevExpress.Web

Assembly: DevExpress.Web.v20.2.dll

NuGet Package: DevExpress.Web

Declaration

C#

[DefaultValue(-1)]
public int GroupIndex { get; set; }

VB.NET

<DefaultValue(-1)>
Public Property GroupIndex As Integer

Property Value

Type	Default	Description
Int32	-1	An integer value that specifies the column’s position among grouping columns. -1 if the ASPxGridView isn’t grouped by the values of the current column.

Remarks

The ASPxGridView supports data grouping by an unlimited number of data columns. To group data by the values of a given column, set the column’s GroupIndex property to a non-negative integer. If several columns are involved in grouping, the GroupIndex property specifies the grouping level. If set to 0, the column is at the root grouping level. Changing the GroupIndex property’s value updates this property value for other columns involved in grouping.

To cancel grouping by the column’s values, set the GroupIndex property to -1 or call the GridViewDataColumn.UnGroup method.

Data grouping is allowed if the ASPxGridViewBehaviorSettings.AllowGroup and ASPxGridBehaviorSettings.AllowSort properties are set to true.

Example

The example demonstrates how to use custom grouping rules to group records by their first letters (the CustomColumnGroup event). The code in the BeforeColumnSortingGrouping event handler, is used to show an invisible column to demonstrate rows which are grouped.

View Example

Default.aspx.cs

using DevExpress.Web.ASPxGridView;

public partial class _Default : System.Web.UI.Page {
    protected int GetGroupNumber(string str) {
        str = str.ToLower();
        char ch = str[0];
        int i = Convert.ToInt32(ch);

        if (ch >= 'a' && ch <= 'e') return 1;
        if (ch >= 'f' && ch <= 'j') return 2;
        if (ch >= 'k' && ch <= 'q') return 3;
        if (ch >= 'r' && ch <= 'v') return 4;
        if (ch >= 'x' && ch <= 'z') return 5;

        return -1;
    }

    protected void grid_CustomColumnGroup(object sender, DevExpress.Web.ASPxGridView.CustomColumnSortEventArgs e) {
        if (e.Column.Name != "VisibleProductName") return;

        int res1 = GetGroupNumber(e.GetRow1Value(e.Column.FieldName).ToString());
        int res2 = GetGroupNumber(e.GetRow2Value(e.Column.FieldName).ToString());

        int res = res1 - res2;

        if (res < 0)
            res = 1;
        else if (res > 0)
            res = -1;

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

    protected void grid_CustomGroupDisplayText(object sender, DevExpress.Web.ASPxGridView.ASPxGridViewColumnDisplayTextEventArgs e) {
        int ind = GetGroupNumber(e.Value.ToString());
        switch (ind) {
            case 1: e.DisplayText = "A-E"; break;
            case 2: e.DisplayText = "F-J"; break;
            case 3: e.DisplayText = "K-Q"; break;
            case 4: e.DisplayText = "R-V"; break;
            case 5: e.DisplayText = "X-Z"; break;
        }
    }

    protected void grid_BeforeColumnSortingGrouping(object sender, DevExpress.Web.ASPxGridView.ASPxGridViewBeforeColumnGroupingSortingEventArgs e) {
        if (e.Column.Name == "VisibleProductName")
            grid.Columns["InvisibleProductName"].Visible = ((grid.Columns["VisibleProductName"] as GridViewDataColumn).GroupIndex != -1);
    }
}

Default.aspx (C#)

<dx:ASPxGridView ID="grid" runat="server" AutoGenerateColumns="False" DataSourceID="sds"
    KeyFieldName="ProductID" OnCustomColumnGroup="grid_CustomColumnGroup" 
    OnCustomGroupDisplayText="grid_CustomGroupDisplayText" OnBeforeColumnSortingGrouping="grid_BeforeColumnSortingGrouping">
    <Columns>
        <dx:GridViewDataTextColumn FieldName="ProductID" ReadOnly="True" VisibleIndex="0">
            <EditFormSettings Visible="False" />
        </dx:GridViewDataTextColumn>
        <dx:GridViewDataTextColumn Name="VisibleProductName" FieldName="ProductName" VisibleIndex="1">
            <Settings AllowGroup="True" SortMode="Custom" />
        </dx:GridViewDataTextColumn>
        <dx:GridViewDataTextColumn Name="InvisibleProductName" FieldName="ProductName" VisibleIndex="2"
            Visible="False">
        </dx:GridViewDataTextColumn>
        <dx:GridViewDataTextColumn FieldName="UnitPrice" VisibleIndex="2">
        </dx:GridViewDataTextColumn>
    </Columns>
    <Settings ShowGroupPanel="True" />
</dx:ASPxGridView>
</div>
<asp:SqlDataSource ID="sds" runat="server" ConnectionString="<%$
    ConnectionStrings:NorthwindConnectionString %>"
    SelectCommand="SELECT [ProductID], [ProductName], [UnitPrice] FROM [Products]">
</asp:SqlDataSource>

Default.aspx (VB.NET)

<dx:ASPxGridView ID="grid" runat="server" AutoGenerateColumns="False" DataSourceID="sds"
    KeyFieldName="ProductID" OnCustomColumnGroup="grid_CustomColumnGroup" 
    OnCustomGroupDisplayText="grid_CustomGroupDisplayText" OnBeforeColumnSortingGrouping="grid_BeforeColumnSortingGrouping">
    <Columns>
        <dx:GridViewDataTextColumn FieldName="ProductID" ReadOnly="True" VisibleIndex="0">
            <EditFormSettings Visible="False" />
        </dx:GridViewDataTextColumn>
        <dx:GridViewDataTextColumn Name="VisibleProductName" FieldName="ProductName" VisibleIndex="1">
            <Settings AllowGroup="True" SortMode="Custom" />
        </dx:GridViewDataTextColumn>
        <dx:GridViewDataTextColumn Name="InvisibleProductName" FieldName="ProductName" VisibleIndex="2"
            Visible="False">
        </dx:GridViewDataTextColumn>
        <dx:GridViewDataTextColumn FieldName="UnitPrice" VisibleIndex="2">
        </dx:GridViewDataTextColumn>
    </Columns>
    <Settings ShowGroupPanel="True" />
</dx:ASPxGridView>
</div>
<asp:SqlDataSource ID="sds" runat="server" ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>"
    SelectCommand="SELECT [ProductID], [ProductName], [UnitPrice] FROM [Products]">
</asp:SqlDataSource>

Default.aspx.vb

Imports DevExpress.Web.ASPxGridView

Partial Public Class _Default
    Inherits System.Web.UI.Page
    Protected Function GetGroupNumber(ByVal str As String) As Integer
        str = str.ToLower()
        Dim ch As Char = str.Chars(0)
        Dim i As Integer = Convert.ToInt32(ch)

        If ch >= "a"c AndAlso ch <= "e"c Then
            Return 1
        End If
        If ch >= "f"c AndAlso ch <= "j"c Then
            Return 2
        End If
        If ch >= "k"c AndAlso ch <= "q"c Then
            Return 3
        End If
        If ch >= "r"c AndAlso ch <= "v"c Then
            Return 4
        End If
        If ch >= "x"c AndAlso ch <= "z"c Then
            Return 5
        End If

        Return -1
    End Function

    Protected Sub grid_CustomColumnGroup(ByVal sender As Object, ByVal e As DevExpress.Web.ASPxGridView.CustomColumnSortEventArgs)
        If e.Column.Name <> "VisibleProductName" Then
            Return
        End If

        Dim res1 As Integer = GetGroupNumber(e.GetRow1Value(e.Column.FieldName).ToString())
        Dim res2 As Integer = GetGroupNumber(e.GetRow2Value(e.Column.FieldName).ToString())

        Dim res As Integer = res1 - res2

        If res < 0 Then
            res = 1
        ElseIf res > 0 Then
            res = -1
        End If

        e.Result = res
        e.Handled = True
    End Sub

    Protected Sub grid_CustomGroupDisplayText(ByVal sender As Object, ByVal e As DevExpress.Web.ASPxGridView.ASPxGridViewColumnDisplayTextEventArgs)
        Dim ind As Integer = GetGroupNumber(e.Value.ToString())
        Select Case ind
            Case 1
                e.DisplayText = "A-E"
            Case 2
                e.DisplayText = "F-J"
            Case 3
                e.DisplayText = "K-Q"
            Case 4
                e.DisplayText = "R-V"
            Case 5
                e.DisplayText = "X-Z"
        End Select
    End Sub

    Protected Sub grid_BeforeColumnSortingGrouping(ByVal sender As Object, ByVal e As DevExpress.Web.ASPxGridView.ASPxGridViewBeforeColumnGroupingSortingEventArgs)
        If e.Column.Name = "VisibleProductName" Then
            grid.Columns("InvisibleProductName").Visible = ((TryCast(grid.Columns("VisibleProductName"), GridViewDataColumn)).GroupIndex <> -1)
        End If
    End Sub
End Class

Related GitHub Examples

The following code snippet (auto-collected from DevExpress Examples) contains a reference to the GroupIndex property.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

C#

gridview-how-to-correct-the-grouped-table-layout-if-column-widths-are-set-in-percentages-t349964/CS/Helpers/GridViewColumnHelper.cs#L64

{
    return Grid.DataColumns.Where(c => c.GroupIndex == -1 && c.Visible);
}

VB.NET

gridview-how-to-correct-the-grouped-table-layout-if-column-widths-are-set-in-percentages-t349964/VB/Helpers/GridViewColumnHelper.vb#L78

Private Function GetVisibleUnGroupedColumns() As IEnumerable(Of GridViewDataColumn)
    Return GridInstance.DataColumns.Where(Function(c) c.GroupIndex = -1 AndAlso c.Visible)
End Function