SSRS expression editor does not recognize embedded code function - function

Question

I have an SSRS report with information about invoices my company has issued with things like amount, date, payment, amount due, etc. I'm using SSRS 2008 (not R2) in Visual Studio 2008 environment. My issue has to do with formatting the report using the Expression editor. Currently, an invoice will be formatted as silver if the invoice has an Amount Due (a column) over 0.01 (outstanding invoice). We also issue credits (negative amounts) and these are almost always the negative amount of a previous invoice.
So, an invoice that has a credit issued to it will still show as silver because it's amount due > 0.01. But if there is a credit issued to this invoice, it's not actually outstanding and should be white. For example, if an invoice is $100.00, and there is a credit after for ($100.00), the original invoice's background color should be switched to white.
Here's where the code explanation comes in. I thought this was possible with custom VB code in the report, but it seems like the Expression editor in SSRS will not recognize my function as it says "Unrecognized identifier". I googled this a bit, and most of the topics I came across said that it will show that but actually work anyway. Well, I'm pretty sure it's not working at all, because I put this in as my expression and got all white cells for a certain column:
=IIF(Fields!Amount_Due.Value > 0.01,
IIF(Code.HasCredit(Fields!Amount_Due.Value) = True, "Blue", "Silver"), "Red")
The HasCredit function is below.
Function HasCredit(ByVal currentAmt as Double) As Boolean
Dim i as Integer
Dim amt as Double
Dim amts as System.Collections.ArrayList = New System.Collections.ArrayList()
Dim negativeAmt as Double
Dim retValue as Boolean = "False"
i = 0
For i = 1 to Report.Parameters!Test.Count()
amt = Report.Parameters!Test.Value(i)
amts.Add(amt)
Next
negativeAmt = currentAmt * -1
If amts.Contains(negativeAmt) Then
retValue = "True"
End If
Return retValue
End Function
When these two pieces are run, I get white background for all cells of this column. I read something on the net saying that only Shared functions would work, but I found multiple other examples showing functions that were not shared that worked. When I make it shared, it gives me: BC30369 Cannot refer to an instance member of a class from within a shared method or shared member initializer without an explicit instance of the class. due to the Report.Parameters!Test.Count() line. I got the idea for using Report.Parameters from http://social.msdn.microsoft.com/Forums/en-US/sqlreportingservices/thread/a7d59224-0ee5-491e-883b-2e5fcb3edeab.
So to reiterate, what I'm basically trying to do is get the values of each cell in this column into a collection and, for any two amounts where one amount has a negative equivalent, give it a white background instead of silver.

Answer 1

In SSRS 2008 R2, even if you reference a valid custom code method, the expression editor may still warn that the identifier is invalid. This does not always mean that it's invalid. My function worked even though that warning was thrown.

Answer 2

After a bit more researching I figured out how to solve this. I basically had to add a textbox with the =Join() function so that all the values in a column were put in this textbox; then reference the textbox in custom code and use a boolean value in the expression editor. Detailed instructions below.
1) Add a multi-valued parameter to your report (Right click Parameters, Add Parameter). Name it, select Allow Multiple Values, select Hidden for parameter visibility. For Available Values tab, select Get values from a query. Point to your dataset, and set the Value field to the column you want the parameter to check. For me that was my Amount Due column. Label field is irrelevant and can be left blank. In the Default Values tab, do the same, make sure the value field is set to the same column as before. Under Advanced, select Never refresh.
2) Create a new textbox on your report. Might want to name it, ex txtColumnValues. Edit the expression and put this in: =Join(Parameters!YourParameter.Value, ",") This will get all of the field values from the column you specified in your parameter, each separated by a comma.
3) Edit your report's custom code and make a VB function (as Boolean) to check the textbox. For example here is my code.
Public Function HasCredit(Amt as Double, ri as ReportItems) as Boolean
Dim retValue as Boolean = False
If Amt > 0.00 AndAlso ri!txtAmounts.Value.Contains(Amt*-1) Then
retValue = True
End If
Return retValue
End Function
4) Finally go to your expression editor for the field you want to change. In my example I wanted to change the background color if the current field had a negative equivalent in one of the other fields (my textbox), so my code looked like this:
=IIF(Fields!Balance.Value > 0.01
AND Code.HasCredit(Fields!Balance.Value, ReportItems) = False, "Silver", "White")
I had to take separate pieces of info from 3 or 4 pages, put them together, and hope they worked... after about a week they did... I guess it's all about persistence. If you need any further help with this just let me know.