The answer fields are dropped in QuestionnaireResponse due to recursive structure.

[bashir2]

This is an issue reported by one of the users and the gist of it is that the answer fields of QuestionnaireResponse resources are dropped in the Parquet files. The root cause of this is the recursive structure of QuestionnaireResponse and the way it is being broken by Bunsen (see this section of SQL-on-FHIR spec for context). Two points about this issue:

• The answer fields at the highest level, i.e., QuestionnaireResponse.item.answer are properly exported to Parquet.
• This issue is not resolved by simply increasing recursive depth (Make recursive depth of Bunsen a configuration parameter. #757) because what is happening is that the first time QuestionnaireResponse.item.item is processed, its answer field is dropped because of recursion, because there are two QuestionnaireResponse.item.answer already on the stack. If we increase the recursive depth, this will still happen.

I have a fix for this where QuestionnaireResponse.item.item objects are differentiated depending on whether any of their child elements are dropped by recursion or not. It is not a perfect solution but it works. Note this issue is similar to some other issues we had with identifier fields here.