Strange errors come during change SourceExpr value in NAV report designer...

Our colleague raised problem: why he receives strange error during report compile, after he changed SourceExpr value for some control in report designer in NAV 2009.

Error message was:

Error while validating RDL content:
The Value expression for textbox “CompanyInfo” refers to the field ‘PricesInclVAT_YesNo’. Report Item expressions can only refers to fields within the current data set scope or, if inside an aggregate, the specified data set scope.

Error itself looks very strange because:
1. It comes from validating RDL content, but we changed nothing in it.
2. Changed was SourceExpr in NAV classic client report designer>sections>control property, and it has no relations to field mentioned in error. Actually what was changed: report 204 – Sales-Quote; control 116; SourceExpr had value "Sales Header"."Prices Including VAT" and now it has value FORMAT("Sales Header"."Prices Including VAT").

If we change back value – error disappears.

After deeper analyze we found that RDL dataset has field ‘PricesInclVAT-YesNo’, but after report designer change SourceExpr value by adding FORMAT – this field disappears from dataset. So problem really is in the SourceExpr value, however value itself is correct. And after few more research we found there is control 167 – name PriceIncVAT_YesNo which has exactly the same SourceExpr value - FORMAT("Sales Header"."Prices Including VAT").

Conclusion: only one source expression is pushed to RDL, if there are few controls with the same SourceExpr, only first will be in RDL, other will not appears there.

I asked NAV architects about this issue and they answered:

The field names that we show in the RDL dataset do NOT come from the SourceExpr property "directly". Each control on a report has a DatasetFieldName property, which is what we use to build the field names in the RDL dataset.

The DatasetFieldName property is then derived from the SourceExpr property the first time you open Visual Studio for a report using the View --> Layout menu item. After this, if you change the SourceExpr, the DatasetFieldName does not get changed. (The whole purpose of this property is to fix the dataset field name so even if you change your SourceExpr, you won’t need to redesign your RDL). This should cover most of the user scenarios.

In a few scenarios, you are not covered though: one is, if you move sections or controls in the layout, and if two controls have the same SourceExpr value, the control we choose to export to the report dataset may change with another one with the same SourceExpr. Since they have different DatasetFieldName properties, your RDL will break. We don’t cover this scenario and we don’t believe that we could fix this easily.

In another scenario: if you change the SourceExpr, and the data type of the new field is different than the old one, RDL compilation may fail due to the expressions used on that field - as these are data type dependent.

So, during report design be very careful with modifying 2 properties: SourceExpr and DataSetFieldName. Changes could impact RDL very much and result could be not you are expecting. Of course this is important if you already have RDL report prepared, if you will create new layout by using "Laoyout suggestion", problems will not come, because new RDl laoyout will be created regarding earlier described rules.

These postings are provided "AS IS" with no warranties and confer no rights. You assume all risk for your use.

Special thanks to John Vestergaard from Logica Danmark A/S for pointing us to this feature.

Gedas Busniauskas

Microsoft Lithuania
Microsoft Customer Service and Support (CSS) EMEA