Handle regular Elixir process messages.

See GenServer.handle_info/2.

Callback implementation for Phoenix.Channel.handle_info/2.

Handle channel joins by topic.

To authorize a socket, return {:ok, socket} or {:ok, reply, socket}. To refuse authorization, return {:error, reason}.

Example

def join("room:lobby", payload, socket) do
  if authorized?(payload) do
    {:ok, socket}
  else
    {:error, %{reason: "unauthorized"}}
  end
end

Callback implementation for Phoenix.Channel.join/3.