Spatie Query Builder Global Search Trough Relationship | Laravel | Page 1

I have two models, "Borrowing" and "Copy", where a copy can have multiple borrowings.

Now I want to have a table that basically lists all the borrowings, but that you can search specifically for a specific field ("barcode_nmbr") of the related copy. I want to implement this with the Spatie Query Builder, but I'm not really getting anywhere. I already have a "copy()" method in the borrowing model that simply returns the BelongsTo Relationship.

This is how it looks so far but it doesn't really work.

#Spatie Query Builder Global Search Trough Relationship