do not save the page on every change

and preserve state

lib/beacon/live_admin/live/page_editor_live/edit.ex

@@ -95,17 +95,13 @@ defmodule Beacon.LiveAdmin.PageEditorLive.Edit do
     {:reply, %{"ast" => ast}, socket}
   end
 
-  def handle_event("update_page_ast", %{"id" => id, "ast" => ast}, socket) do
-    page = Content.get_page(socket.assigns.beacon_page.site, id, preloads: [:layout])
-
-    case Content.update_page(socket.assigns.beacon_page.site, page, %{"ast" => ast}) do
-      {:ok, page} ->
-        {:noreply, assign(socket, :page, page)}
+  def handle_event("update_page_ast", %{"ast" => ast}, socket) do
+    send_update(Beacon.LiveAdmin.PageEditorLive.FormComponent,
+      id: "page-editor-form-edit",
+      ast: ast
+    )
 
-      # FIXME: handle update ast error
-      {:error, _changeset} ->
-        throw("How should we handle this?")
-    end
+    {:noreply, socket}
   end
 
   @impl true

lib/beacon/live_admin/live/page_editor_live/form_component.ex

@@ -4,6 +4,7 @@ defmodule Beacon.LiveAdmin.PageEditorLive.FormComponent do
   alias Beacon.LiveAdmin.Config
   alias Beacon.LiveAdmin.Content
   alias Beacon.LiveAdmin.WebAPI
+  alias Ecto.Changeset
 
   @impl true
   def update(%{site: site, page: page} = assigns, socket) do
@@ -41,6 +42,29 @@ defmodule Beacon.LiveAdmin.PageEditorLive.FormComponent do
     {:ok, assign_form(socket, changeset)}
   end
 
+  def update(%{ast: ast}, socket) do
+    template = Beacon.Template.HEEx.HEExDecoder.decode(ast)
+    params = Map.merge(socket.assigns.form.params, %{"template" => template})
+    changeset = Content.change_page(socket.assigns.site, socket.assigns.page, params)
+
+    case Changeset.apply_action(changeset, :update) do
+      {:ok, page} ->
+        # TODO: remove web api
+        %{data: builder_page} = WebAPI.Page.show(page.site, page)
+
+        {:ok,
+         socket
+         |> assign_form(changeset)
+         |> assign(:template, page.template)
+         |> assign(:changed_template, page.template)
+         |> assign(:builder_page, builder_page)}
+
+      _ ->
+        # TODO: handle errors
+        {:ok, socket}
+    end
+  end
+
   @impl true
   def handle_event(
         "validate",