How to set the default value of a field depending on a relationship item

Help
1

Hi guys! :waving_hand:

In the app I am trying to set the default value of a field to the value of a relationship item’s field.

Let’s say I have the collection event which has several talks. The event has a start_date and an end_date. talk has a single date field and a relational event.
Whenever I create a talk I want to set the default value of talk.date to event.start_date. I tried to set {{ event.start_date }} as the default value of talk.date but this does not work.

Any tips on this issue?

2

Curious what you learn.

We have several similar use cases, such as:
If I add company A, then go to pick people, I only want to see people from Company A. If Company A only as 1 person associated with it, then autocomplete to that person.
If I mark a product as belonging to a certain category, then go to add tags, I only want to see product tags which have already been associated as pertaining to that category.

Similar but not exactly the same as your question.