From my research, I think the answer to this question is, "it can't be done", but I'm hoping I'm missing something.
My base has 3 tables:
- Waiting List - this is the "main" table, listing the people on the waiting list.
- Events - defines the events for which people may be waitlisted.
- Site Types - lists the possible site types that could be available to a person on the waiting list.
Here's a highly simplified version of the base that illustrates the setup.
Each record in the Waiting List table is linked to a single Event Name record in the Events table.
Each record in the Events table is linked to one or more Site Types in the Site Types table. This link field defines the subset of Site Types that are available for that particular Event. This data is repeated as "Available Site Types" in the Waiting List table via a lookup field (if it's needed). As I have it set up, one Site Type record can be linked to multiple different Event records, but that's not mandatory--if it helped solve the problem, the Site Types could be unique to each Event.
The "Join the waiting list" form in the Waiting List table is used for data entry. In an ideal world, the form would display a Multiple Select field with the Site Types available for that event--but I realize that the options for this type of field can't be dynamically populated.
So instead, the form displays the link field to Site Types. The form is pre-populated with the Event Name, which is hidden so the user can't change it, and all the Site Types available for that event as defined in the Events table. The user is instructed to remove (click the "x") on each site type they would not be willing to accept if offered to them. Here are two examples for two different events:
- Waiting list form for Los Angeles event (offers site types A & B)
- Waiting list form for New York event (offers site types C & D)
This actually works pretty well, unless the user hits the "+ Add" button. Then they will see ALL of the Site Types, including ones that don't apply to that Event. Instead, I'd like the list of Site Types they see to be limited to those that are listed in the Site Types field of the Events table. I can't seem to find a way to do that. (Suppressing the display of the + Add button would be another avenue, but I don't think that's possible either.)
Limiting the record selection to a view in the form field doesn't solve the problem, because as far as I can tell there is no way to dynamically filter a view to just the subset of available Site Types.
Any ideas?