broadcast updates

lib/acme/orders.ex

@@ -68,9 +68,12 @@ defmodule Acme.Orders do
 
   """
   def update_order(%Order{} = order, attrs) do
-    order
-    |> Order.changeset(attrs)
-    |> Repo.update()
+    order_changeset = Order.changeset(order, attrs)
+
+    with {:ok, order} <- Repo.update(order_changeset) do
+      Phoenix.PubSub.broadcast(Acme.PubSub, "orders:#{order.id}", {:order_updated, order})
+      {:ok, order}
+    end
   end
 
   @doc """

lib/acme_web/live/order_live/show.ex

@@ -10,12 +10,19 @@ defmodule AcmeWeb.OrderLive.Show do
 
   @impl true
   def handle_params(%{"id" => id}, _, socket) do
+    if connected?(socket), do: Phoenix.PubSub.subscribe(Acme.PubSub, "orders:#{id}")
+
     {:noreply,
      socket
      |> assign(:page_title, page_title(socket.assigns.live_action))
      |> assign(:order, Orders.get_order!(id))}
   end
 
+  @impl true
+  def handle_info({:order_updated, order}, socket) do
+    {:noreply, assign(socket, :order, order)}
+  end
+
   defp page_title(:show), do: "Show Order"
   defp page_title(:edit), do: "Edit Order"
 end