Join vs after_join

Phoenix Forum Questions / Help
1

Just got a question while implementing Phoenix channel.

What kind of functions should be put in “join” and what kind of functions should be executed in “handle_info(:after_join…)” ?

For example I have actions to take when user join:

  1. user to subscribe to an external topic
  2. Presence.track user

Should I put all of those to handle_info(:after_join…) ?
Thank you = )

2

Put in anything in :after_join that requires the socket since the socket is not ‘set up’ until after join returns. :slight_smile:

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3

Aha, now I understand the reason. Thank you for the reply! = )

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4

Also I think join in phoenix channels is somewhat similar to init in a genserver. So the same rules apply, you would not want to put something slow in init or join, but instead handle it later with handle_info. Since neither of your actions are particularly slow, I don’t see anything wrong with putting them in join.

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5

Except you cannot broadcast the startup presence data from it since the topic is not fully up yet too, needs to be in after_join.

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