For my app, I needed to perform a specific query, and the best way to do it was to create a custom action. The action looked great, but when I tried to test it, I encountered some difficulties. It seemed like the action didn't want to work.
To test it, I was calling the action on page load and creating children from the output, but nothing was being displayed. I tried hard to make it work, but nothing seemed to fix the issue.
Finally, I figured it out. To make it work, you can't just call the action from the output; you need to first add an action ("update page state") with no specific instructions to reload the page, and then the custom action will appear.
So, remember, if you want to use a custom action to query a collection, after calling the action, add an "update page state" action with the "reload the page" option to make it work. This way, you will be able to call the action output from anywhere on your page.
Flutterflow team, if you're reading this, it would be great to have more "advanced" official documentation on custom actions and functions.