I created a GenServer to keep track of the current index in case the client reconnects to the socket. I intend to only use one GenServer.

I can make the GenServer start automatically by adding it to the children list of supervisor but my GenServer state is depended on the result of a query so I cannot put it there.

 children = [
      # Start the Ecto repository
      Senti.Repo,
      ...
      {Senti.QuestionState, [%{}]}
    ]

I started the GenServer in my join callback. I’m aware that the start_link will always be called when there are new clients connected but I have no idea where should I put this one.

I have my code below to describe more about my issue.

  def join("session:" <> session_id, _payload, socket) do
    presentation_state = Questionnaire.get_presentation_info(session_id)
    {:ok, _pid} = QuestionState.start_link(question_state(presentation_state))

    question_index = QuestionState.get_next_question_index() || 0

    {:ok, %{presentation: presentation_state, current_index: question_index}, socket}
  end

If information provided above is insufficient, I will update it ASAP.
Thank you.