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Working Around Microsoft’s ReportViewer #Error Bug

Posted on 13. Jul, 2010 by Eric in Other

I’ve begun developing reports in .NET, and just starting up the learning curve. Basic reports are pretty easy, but if you need anything complex things get convoluted in a hurry. I don’t know if my Visual FoxPro experience is getting in the way of wrapping my head around the .NET way, but it sure seemed things were a lot easier in Visual FoxPro!

Recently I had to do something quite simple: put a custom header on a report to show the name of the event. I added a textbox, and found what seemed like the perfect report variable to drop in there to use: Globals!ReportName. The docs said that was related to ReportViewer.LocalReport.DisplayName, but ok I can deal with a little inconsistency. I set the .DisplayName in my code to the custom info, ran the report, and voila! Huh? #Error appeared in the field.

I doublechecked the expression, which automagically changed itself to [&ReportName] or somesuch, so I changed it back, ran it again, and … #Error.

WTF? Was it not getting the ReportName properly? I changed it to another expression, this time Globals!TotalPages (and again it changed itself to &TotalPages), but to no avail.

I googled and found others were having a similar problem. Excellent, then there’d be a solution! Alas, Brad at Microsoft couldn’t reproduce the problem at all. I spent a lot more time researching possible solutions before coming to the conclusion that the Globals! idea just wasn’t going to work. I tried to use Parameters! too but those didn’t work either.

Finally I hit upon an idea for a workaround. I’d have to pass the custom information I wanted into the report in the same manner that I passed the data that appeared on the report: using a DataTable. I didn’t want to add a column to the existing DataTable because that would offend my refined sense of normalization. What I needed was a second DataTable in the DataSet.

Could this be done? Turns out it can. Here’s what you do:
1. Create a new data schema. (Right-click on the project, select Add New Item, pick DataSet). Give it a name like ReportInfo. Add all the columns you might want on a report, such as Title, Author, whatever.
2. Right+Click on your RDLC and say “Open With…” and pick XML Text Editor.
3. Under the DataSources section, add a new DataSource:


System.Data.DataSet
/* Local Connection */

4fa27bef-71ac-4304-8e50-89e232563f2a


4. Under the DataSets section, add a new DataSet



Title
System.String



ReportInfo
/* Local Query */


ReportInfo_ReportInfo
[Path to your File]\ReportInfo.xsd
ReportInfo


5. Close your RDLC and re-open it in the designer. Drop a TextBox in the header, and select your new Title field. It’ll say =First(), but that’s ok.
6. Now in the code where you called your report, you need to create your DataTable and add it to your report’s DataSource, like this:
DataTable dtReportInfo = new DataTable("ReportInfo");
dtReportInfo.Columns.Add(new DataColumn("Title", System.Type.GetType("System.String")));
dtReportInfo.Rows.Add(this.ReportViewer1.LocalReport.DisplayName + " " + cTitle.ToString());
ds.Tables.Add(dtReportInfo);
this.ReportViewer1.LocalReport.DataSources.Add(new ReportDataSource("ReportInfo_ReportInfo", this.ds.Tables[1]));

(StringBuilder cTitle contains the title information that I built up).

There you go! Now you can get the info you need on your report with relying on the Globals! variables and getting an #Error. We’re still not sure why we were getting that, but at least we have a workaround. I hope you find this post and it doesn’t cost you hours and hours of unbillable time, like it did me.