Problem with grouping and aggregate functions.

[Evgeny]

Hello. I have such problem: when I try to add aggregate functions for group, that was created from user interface(user drags column headers to grouping panel), i cant use foreach for groups collection, that have more than one element. I get exception, that talk my group collection has changed. But i changed only aggregate functions collection. Code demonstrated such behaviour is below:

foreach (var group in AssociatedObject.GroupDescriptors)

{

    var localGroup = (group as GroupDescriptor);

 

    AggregateFunctionCollection aggregateFunctions = localGroup == null ?

        (@group as ColumnGroupDescriptor).Column.AggregateFunctions :

           localGroup.AggregateFunctions;

 

   aggregateFunctions.Clear();

 

    aggregateFunctions.Add(new CountFunction { Caption = GroupAggregatesName });

}

What is the way to solve this problem? Please help.

[Vlad]

Hi,

When you group using drag & drop the grid will add ColumnGroupDescriptor. You can use for example:

foreach (var group in AssociatedObject.GroupDescriptors.OfType<ColumnGroupDescriptor>())

Regards,
Vlad
the Telerik team

[Evgeny]

It's right. But I have in my collection GroupDescriptor and ColumnGroupDescriptor, because I use grouping at the start of my application. And it always make exception, when collection contain different type descriptors.

[Evgeny]

I found it doesn't work if there are more than one ColumnGroupDescription in GroupDescriptors collection. Always throw exception, thatGroupDescriptors collection was changed after changing AggregateFunctions collection. I can't iterate groups in GroupDescriptors collection. So what is the right way to resolve this problem?