How do I implement optional grouping in SSRS 2008?

I have a report table in SSRS 2005. It looks like this:

Group Header Row
  Group Detail Rows
Group Footer Row

The groups are displayed based on a report parameter called GroupBy. If this parameter is null, then there is no grouping. So, the Visibility.Hidden property expression is set to =Parameters!GroupBy.V开发者_开发技巧alue is Nothing for the header and footer. The visibility of the detail row is set to =Not(Parameters!GroupBy.Value is Nothing).

When rendering the report with GroupBy = null, the report hides the header and footer and displays all the detail rows. This means the toggle is hidden and it just looks like a normal, group-less report.

In SSRS 2008, this little trick no longer works. If the group header is hidden, then the details rows are also hidden.

Any ideas on how to hack this functionality into SSRS 2008?

What you can do is apply the visibility to the row of the group header (not the group itself). You can do this by selecting the row, right clicking the edge and selecting "Row Visibility..." You could do this for both the group header and group footer. Also, I used this expression for the visibility:

=CBOOL(Parameters!GroupBy.Value IS NOTHING)