When the client goes away the socket is severed which means ALL of client’s subscriptions are unsubscribed. I am already catching it quite happily via AbsintheChannelDecorator’s terminate(reason, socket) callback. Again, it lacks useful information in arguments, but one can assume that all subscriptions are cancelled when browser window is closed.
What’s really a major pain point is that absinthe/phoenix gives you a single endpoint to handle all subscribe and unsubscribe actions AND the arguments are not very informative:
def handle_in(event = “unsubscribe”, payload = %{“subscriptionId” => subscription_id}, socket)
The payload doesn’t tell you which channel was unsubscribed from (even though you had provided the channel names in the config in your absinthe schema, and all you have is a subscriptionId. That means that you have to create your own registry of subscriptionIds to map them to that information when you subscribe to be able to run some subscription-specific logic like lock release in my example on unsub. Why??? Absinthe is already doing that in its own handle_in() implementation.
I wish there was a callback function I could specify in the channel config in the absinthe schema, or at least absinthe would pass channel name back to me in handle_in args - then I could use naming to extract the arguments, e.g. “lock-changed:<object_type>:”.
So, unless I’m misusing Absinthe, my solution so far is to stash channel name into redis cache keyed by subscriptionId. But then you have to start thinking about expiring those entries eventually and renewing the expiration timestamp when the key is in use… This is way too complicated when all the information is already provided to the framework.
