Question

I have a book tracker that includes Databases to track properties of books, such as "Categories" (Fiction or Non-Fiction), "Genres" (Fantasy, Sci-Fi, and Business), and "Sub-Genres" (Epic, High, and Biographies. Each Database references the one before it. From the Book DB I created relations between Books and Categories, Books and Genre, and Books and Sub-Genre. The Genre DB includes a column specifying whether the Genre is Fiction or Non-Fiction and the Sub-Genre does the same, but for Genres. I want to cascade or limit my dropdown selection based on the higher-level section, i.e., if I select Fiction, only Fantasy and Sci-Fi will be shown as options from the Genre field. Google tells me I need to filter the relation before I add it, but that function seems to have changed, and the Filter functions within the Books DB won't allow the source for the filter to be from outside the Books DB. It appears it was possible to do what I want, but the process has changed. Here is my current test.

https://www.notion.so/Testing-relationships-267791676954808da47dd420e6ae8236?source=copy_link

Answer 1

The view filter on Books is the wrong place. Google was talking about the relation property itself.

You cannot cascade Selects. You already have the right shape: Categories, Genres, Sub-genres as databases.

On the Books database, open the Genre relation, not the view filter. Look for Limit, or Filter this relation. Set it so the Genre’s Category matches this book’s Category. Same on Sub-genre: Sub-genre’s Genre matches this book’s Genre.

If that Limit control is missing, the property is a Select, or the relation is not pointing at the Genre database. Relations only.

You pick Category first, then Genre only shows what belongs. Same for Sub-genre. There is no way to make a Select option list shrink.