SSRS. Hide a Column based on Row Group Value

Question

My application uses SSRS to produce payslips for employees. The Payslip report consists of a tablix with 5 columns. Among the 5, is a column called " Units " and another called " Invoice value ".

The report has several Row Grouping levels, but the only important one for this question is the Payslip Number Row Grouping "RG_SlipNum". There is a page break after each "RG_SlipNum" RowGroup.

When users want to print Payslips, they can optionally supply up to 5 parameters which filter the result set to print out.

Employees can be paid based on the number of units delivered * a rate (Unit Based), or by a percentage of the invoice value (Invoice based) for the delivery (Oversimplified, but hopefully, you get my drift).

If the employee is Unit based I want the Units Column to Show, and the "Invoice Value" Column to be hidden. If they are Invoice based I want both columns to show.

My dataset has a bit field indicating whether to show or hide a column based on the logic above. It will be a 1 or a 0 for every underlying row within the current rowGroup. I have tried to use the First(,) function in a Column Visibility expression on the "Invoice Value" Column. However, I get the following error whenever I try to limit the scope of the First Function to the current Payslip Rowgroup using the RowGroup name.

"The Hidden expression for the tablix 'X' has a scope parameter that is not valid for an aggregate function. The scope parameter must be set to a string constant that is equal to either the name of a containing group, the name of a containing data region, or the name of a dataset. "

So, my Question(s)

Can you define a RowGroup name as the Scope argument in a First() function ?

If not, What's the best way of achieving this without completely re-working my Dataset / RDL to accomplish this. (Using SSRS2008)

Answer 1

Why is it always just after posting a forum question, you figure it (or some workaround) out?

I'd still like some (better) answers if anyone sees this, but I've set a cell in the tablix to the value of the bit field that determines whether to show the column or not. I then changed my Column Visibility expression to check the cell value (using ReportItems!textboxname.Value) and it's working. as I scroll the payslips the columns visibility changes appropriately.