Exclude certain rows from Column Aggregate

Description

Sometimes one might want to exclude specific rows from being aggregated.

This will require using custom aggregation.

Solution

1. Set the Aggregate property of the Column to Custom.
2. Bind the OnCustomAggregate event to the Grid.
3. In the event handler, you can calculate the values you want and update the footer accordingly

Example

<telerik:RadGrid
    ID="RadGrid1"
    runat="server"
    AllowPaging="True"
    Width="800px"
    OnNeedDataSource="RadGrid1_NeedDataSource"
    OnCustomAggregate="RadGrid1_CustomAggregate"
    MasterTableView-ShowGroupFooter="true"
    ShowGroupPanel="true"
    ShowFooter="true">
    <ClientSettings AllowDragToGroup="true">
    </ClientSettings>
    <GroupingSettings ShowUnGroupButton="true" />
    <MasterTableView AutoGenerateColumns="false">
        <GroupByExpressions>
            <telerik:GridGroupByExpression>
                <GroupByFields>
                    <telerik:GridGroupByField FieldName="Group" />
                </GroupByFields>

                <SelectFields>
                    <telerik:GridGroupByField FieldName="Group" />
                </SelectFields>
            </telerik:GridGroupByExpression>
        </GroupByExpressions>
        <Columns>
            <telerik:GridBoundColumn DataField="MyField" HeaderText="MyField" DataType="System.String" Aggregate="Custom" />
            <telerik:GridBoundColumn DataField="Group" HeaderText="Group" />
        </Columns>
    </MasterTableView>
</telerik:RadGrid>

    private DataTable OrdersTable()
    {
        DataTable dt = new DataTable();

        dt.Columns.Add(new DataColumn("MyField", typeof(string)));
        dt.Columns.Add(new DataColumn("Group", typeof(string)));

        for (int i = 0; i < 10; i++)
        {
            int index = i + 1;

            DataRow row = dt.NewRow();

            row["Group"] = index % 2 == 0 ? "Group 1" : "Group 2";

            if (index == 2)
            {
                row["MyField"] = DateTime.Now.Date.ToString();
            }
            else
            {
                row["MyField"] = 1;
            }

            dt.Rows.Add(row);
        }

        return dt;
    }

    protected void RadGrid1_NeedDataSource(object sender, GridNeedDataSourceEventArgs e)
    {
        RadGrid grid = sender as RadGrid;
        DataTable sourceData = OrdersTable();
        grid.DataSource = sourceData;
    }

    protected void RadGrid1_CustomAggregate(object sender, GridCustomAggregateEventArgs e)
    {
        if (e.Column.UniqueName == "MyField")
        {
            if (e.Item is GridGroupFooterItem) // Custom Aggregate for the items within the Group
            {
                GridGroupFooterItem groupFooterItem = (GridGroupFooterItem)e.Item;
                GridGroupHeaderItem groupHeaderItem = groupFooterItem.GroupHeaderItem;

                GridItem[] groupChildItems = groupHeaderItem.GetChildItems();

                decimal counter = 0;

                for (int i = 0; i < groupChildItems.Length; i++)
                {
                    GridDataItem dataItem = groupChildItems[i] as GridDataItem;

                    if (dataItem != null)
                    {
                        decimal numericValue = 0;

                        if (decimal.TryParse(DataBinder.Eval(dataItem.DataItem, "MyField").ToString(), out numericValue))
                        {
                            counter += numericValue;
                        }
                    }
                }
                e.Result = counter;
            }
            else if (e.Item is GridFooterItem) // Custom Aggregate for all items in the Grid
            {
                double sum = 0;

                DataTable dt = RadGrid1.DataSource as DataTable;

                foreach (DataRow row in dt.Rows)
                {
                    double numericValue;

                    if (double.TryParse(row["MyField"].ToString(), out numericValue))
                    {
                        sum += numericValue;
                    }
                }
                e.Result = sum;
            }
        }
    }

Class SurroundingClass
    Private Function OrdersTable() As DataTable
        Dim dt As DataTable = New DataTable()

        dt.Columns.Add(New DataColumn("MyField", GetType(String)))
        dt.Columns.Add(New DataColumn("Group", GetType(String)))

        For i As Integer = 0 To 10 - 1
            Dim index As Integer = i + 1
            Dim row As DataRow = dt.NewRow()

            row("Group") = If(index Mod 2 = 0, "Group 1", "Group 2")

            If index = 2 Then
                row("MyField") = DateTime.Now.Date.ToString()
            Else
                row("MyField") = 1
            End If

            dt.Rows.Add(row)
        Next

        Return dt
    End Function

    Protected Sub RadGrid1_NeedDataSource(sender As Object, e As GridNeedDataSourceEventArgs)
        Dim grid As RadGrid = TryCast(sender, RadGrid)
        Dim sourceData As DataTable = OrdersTable()
        grid.DataSource = sourceData
    End Sub

    Protected Sub RadGrid1_CustomAggregate(ByVal sender As Object, ByVal e As GridCustomAggregateEventArgs)
        If e.Column.UniqueName = "MyField" Then

            If TypeOf e.Item Is GridGroupFooterItem Then
                Dim groupFooterItem As GridGroupFooterItem = CType(e.Item, GridGroupFooterItem)
                Dim groupHeaderItem As GridGroupHeaderItem = groupFooterItem.GroupHeaderItem
                Dim groupChildItems As GridItem() = groupHeaderItem.GetChildItems()
                Dim counter As Decimal = 0

                For i As Integer = 0 To groupChildItems.Length - 1
                    Dim dataItem As GridDataItem = TryCast(groupChildItems(i), GridDataItem)

                    If dataItem IsNot Nothing Then
                        Dim numericValue As Decimal = 0

                        If Decimal.TryParse(DataBinder.Eval(dataItem.DataItem, "MyField").ToString(), numericValue) Then
                            counter += numericValue
                        End If
                    End If
                Next

                e.Result = counter
            ElseIf TypeOf e.Item Is GridFooterItem Then
                Dim sum As Double = 0
                Dim dt As DataTable = TryCast(RadGrid1.DataSource, DataTable)

                For Each row As DataRow In dt.Rows
                    Dim numericValue As Double

                    If Double.TryParse(row("MyField").ToString(), numericValue) Then
                        sum += numericValue
                    End If
                Next

                e.Result = sum
            End If
        End If
    End Sub
End Class