Getting message for disconnection of client or Phoenix server

[lalarukh]

My client and server are communicating consecutively but I want a method that notify when client disconnect from server in handle_in function. As handle_in function is providing response back and everything.
Here’s my handle_in fucntion in room_channel:

def handle_in("message:add", %{"message" => body}, socket) do
    room_id = socket.assigns[:room_id]
    broadcast!(socket, "room:#{room_id}:new_message", %{body: body})
    IO.puts("Received Message from Client: #{body}")
    {:reply, {:ok, %{from: "server", body: body}}, socket}
end

This is how I’m getting response back in client from server:

def respond(payload):
  print(payload)

channel.push("message:add", {"message": "HELLO WORLD"}, respond)

[dimitarvp]

Pheonix → Phoenix

[derpycoder]

There’s interesting discussions about this:

Can Phoenix channel detect client offline immediately?Like WiFi disconnected

An instant event in this case is technically impossible. Only the client knows about the cut down WiFi. But since WiFi is down, it can’t tell the server. There might even be situations in which neither of the participants know about the disconnect. Lets say your ISP drops the connection. Neither your client nor your server will know this until they try the next heartbeat and it times out. This is just how networking works.

---

I saw a snippet in auto generated auth code: DerpyCoderWeb.Endpoint.broadcast(live_socket_id, “disconnect”, %{})

That broadcasts disconnect event on logout.

So I was thinking that same event gets fired for socket disconnect, which we can handle.

And of course we have to lower the heartbeat interval, so we can detect when client disconnects quickly.

[lalarukh]

How can I add the disconnection functionality in handle_in function. Because my handle_in function is joining and responding back to the client.