Hello there, I have a question that I have not fully answered. I need to create a record list inside a record list in C#. I create the object but when I try to add a record list to the primary record list, it crashes. The error that is shown in the service center is "Object reference not set to an instance of an object.". The list that will be added to the primary list is not empty, it has values. Could anyone enlightenment me to create a nested record list. Any examples? Thanks in advance. 

Why do you need to do this in C#? You can do a list of lists inside the platfrom itself.

It's because I am doing a query to a database. Outsystems can only iterate through the columns in sequential manner. Example(Record 1 -> column1, column2, column3...n)(Record 2 -> column1, column2, column3...n). I am trying to organize the data in a record list with an identifier, and data in form a of a record list(hence nested).

RecordMain(identifier, dataList), dataList(header, data). If anyone has a better approach will gladly hear it. Thanks.

you should be able to do that inside OutSystems just with a loop and the listAddItems,etc methods