In sheet 1 I have seminars with participants. I labeled the columns: participant 1, participant 2, …
Glide creates a relation column out of this data.
In another sheet I have a list of all users.
I then use the 1st relation to create a 2nd relation where participant names match to app users.
This works very well: I can list all participant profiles on a seminar tab using the 2nd relation.
My question: How do I identify missing users? Some participants names are not listed in the users sheet. I’d like to list those participant names as well - but atm I have no clue how to access this data.
Because: the 1st relation created by glide is not accessible in components.
What you created is an array column. Not a relation column. Although they both have the same icon, they are very much different in function. How you are using it is correct, by using the array to create the second relation, but I just wanted to clarify that part.
For your question, I think you would need to also create a relation for each individual Participant column. Then create a component for each participant column and set visibility if the respective relation is empty. That would be extremely messy, but the only thing I can think of. I would maybe consider restructuring your data. First have your Seminar sheet. Then your Users sheet. Then a third sheet that contains the Seminar and User. Create a relation to link the Seminar in the Seminar sheet to the Seminar in the SeminarUser sheet. Then create a relation in the SeminarUser sheet to the User sheet. This would let you add a list of all users to the Seminar details page regardless if they have a User record or not. Then within the SeminarUser details, you can either create another list to the user details or use a series of Lookups against the Relation to display all of the user details.