listener.ex

defmodule PostgresPubSub.Listener do
  use GenServer

  def child_spec(opts) do
    %{
      id: __MODULE__,
      start: {__MODULE__, :start_link, [opts]}
    }
  end

  def start_link(opts \\ []),
    do: GenServer.start_link(__MODULE__, opts)

  def init(opts) do
    with {:ok, _pid, _ref} <- PostgresPubSub.Repo.listen("accounts_changed") do
      {:ok, opts}
    else
      error -> {:stop, error}
    end
  end
end