Data Grid - Unable to get associated attribute

I am new to Mendix, and not able to understand, why is this happening. I have created a Work order overview page with a button that takes to Work order details page, for every Work order. There is one to one association between WorkOrders and WO_details entity.   Details page has a Data grid, which triggers a microflow, having a SQL query connecting to external database, it returns a List of WO_Details entity.   Data grid gets populated with all the columns of the WO_Details entity, but I also want to add a column for WO number. I am able to select the association Workorders_WODetails, and I can select Work_Order_Number attribute of WorkOrders entity.  But it doesn’t show up on the page. I have tried retrieving it by association in the microflow itself and adding it to the List, but it did not work. When I tried a List view, it added Work_Order_Number, with same association link automatically, and it still doesn’t show up on page. But List view gave me an option to add an expression instead of attribute, and this works. Please tell me how to get this in data grid instead of List view, as that is the format I desire, also I want to understand what am I missing.
1 answers

Not sure what the exact config is of the DB query and result handling.

But my guess is that you do retrieve a list of WO_Details, but without the reference set to a WorkOrder. So when viewing the data, over association no data is accessible.

You need to reference the WO_Details to the WorkOrder.