Intersoft Community - Lounge - Using a CustomAggregate result in a group header's GroupRowInfoText

Using a CustomAggregate result in a group header's GroupRowInfoText

RobertPehrson — Tue, 26 Jul 2011 11:43:49 GMT

Here is an outline of my workaround to show how a group value can be aggregated and included in formatted text in the group header.

The process is initiated by the InitializeRow event:

grid.InitializeRow += OnInitializeRow;

The event handler picks out the rows that are group headers. In my application, there are nested groups, and the whole group hierarchy has to be processed to aggregate values; so my InitializeRow handler picks out the group headers at the top of the hierarchy:

private void OnInitializeRow(object sender, ISNet.WebUI.WebGrid.RowEventArgs e)
{
    WebGridRow row = e.Row;

    if (row.Type == RowType.GroupHeader)
    {
        if (row.Parent == null)
        {   
            // this group header row is at the top of the group hierarchy
            PopulateGroupHeader(row);
        }
    }

    e.ReturnValue = true;
}

The processing is done in a method that is called recursively for each level of the group hierarchy.

private void PopulateGroupHeader(WebGridRow row)
{
    WebGridGroup group = row.GetGroup();

    // Detect which group is being processed...
    string col = group.Column.DataMember; 

    if (col == "outerGroupColumn")
    {
        // For nested groups, process the child groups...
        foreach (WebGridRow childRow in row.Children)
        {
            PopulateGroupHeader(childRow);
        }
    }
    else if (col == "innerGroupColumn")
    {
        // Process each row in the inner group...
        foreach (WebGridRow leafRow in row.Children)
        {
            if (leafRow.DataRow != null)
            {
                DataRow r = ((DataRowView)leafRow.DataRow).Row;

                // Access the columns in this row to form aggregated data...
                object datavalue = r["ColumnName"];
            }
        }

        //Use the aggregated data in a formatted string and place in the group header...
        row.Cells[0].GroupRowInfoText = "formatted text";
    }

Using a CustomAggregate result in a group header's GroupRowInfoText

MarTin — Mon, 25 Jul 2011 22:50:03 GMT

Hello Robert,

Would you mind to provide us with the sample that you have successfully worked on?

Your sample would be very useful to be converted into a knowledge base, so that other user will get the benefit from your workaround sample.

Thank you.

Regards,
-Martin-

Using a CustomAggregate result in a group header's GroupRowInfoText

RobertPehrson — Fri, 22 Jul 2011 10:32:11 GMT

Hi Martin

Thanks for your confirmation that custom aggregate is not available in group headers.

I do have a workaround. Picking up each group header in an InitializeRow event handler, traversing its child rows to accumulate the aggregate result, and constructing the text using the result, I can then place the formatted text in the row's Cells[0].GroupInfoText.

Regards

Robert

Using a CustomAggregate result in a group header's GroupRowInfoText

MarTin — Fri, 22 Jul 2011 03:35:43 GMT

Hello Robert,

I understand your point here, but it seems that using custom aggregate is not available for GroupRowInfoText in the group header.

The sample shows the implementation custom aggregate on a column footer. You only need to set FooterText, i.e "Count = " and set AggregateFunction to custom.

However, this is not applicable in Group header since it can be only used for built-in aggregate function only. Therefore, if you set GroupRowInfoFormat to [custom], it will display custom instead of the value being generated in custom aggregate.

Hope this helps. Thank you.

Regards,
-Martin-

Using a CustomAggregate result in a group header's GroupRowInfoText

RobertPehrson — Thu, 21 Jul 2011 12:47:04 GMT

I am grouping grid rows and wish to use a CustomAggregate event handler to calculate a result from the grouped rows, and display that result in the group header.

My problem is that I cannot find any syntax for the GroupRowInfoText to include the custom aggregate in the group header. We have [caption], [value], [count], and the built-in aggregate functions [sum()] [avg()], [min()] and [max()]. I guess I need something like [custom].

The documentation and the example show a custom aggregate being added to a footer, but without a substitution tag - i.e. "Count =", and the aggregate value gets placed at the end. Placing the custom aggregate at the end wouldn't be as flexible as a substitution tag, but it doesn't happen in group headers.

Can you explain how to get a custom aggregate into a group header?

Thanks

Robert