Programming Phoenix LiveView B2.0: Presence must be started (pg 243 ff)

When setting up the PentoWeb.Presence module, it is not addressed there (or just not clearly enough for me :)) that it has to be added as a child process to the supervisor and that it must be called after the PubSub child.

Test-driving the code following just the book leads to an (unfortunately not too helpful) “argument error” in PentoWeb.Presence.get_by_key/2 when visiting a product page and the same when just calling PentoWeb.Presence.list(“user_activity”) if it is not started this way.

Thanks for pointing this out! I’ll add the instruction to add the Presence module to your application’s children. You can look out for that in the next release :slight_smile: