vaccins/lib/vaccins_web/live/index.ex

defmodule VaccinsWeb.IndexLive do
  use VaccinsWeb, :live_view
  alias Vaccins.{LocationStore, Search}

  @impl true
  def mount(_params, _session, socket) do
    locations = LocationStore.get_locations()

    {:ok,
     socket
     |> assign(
       locations: locations,
       pending: %{},
       availabilities: locations |> Map.new(&{&1.id, []})
     )}
  end

  @impl true
  def handle_info({:query_sent, id, ref}, socket = %{assigns: %{pending: pending}}) do
    {:noreply, socket |> assign(pending: pending |> Map.put(ref, id))}
  end

  @impl true
  def handle_info(
        {:query_result, ref, res},
        socket = %{assigns: %{locations: valid, pending: pending}}
      ) do
    id = pending |> Map.get(ref)
    send_update(VaccinsWeb.LocationComponent, id: id, availabilities: res)
    {:noreply, socket |> assign(pending: pending |> Map.delete(ref))}
  end
end