Start new notebooks with a focused code cell (#527)

* Start new notebooks with a focused code cell

* Update changelog

CHANGELOG.md

@@ -15,6 +15,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ### Changed
 
 - Improved intellisense to handle structs and sigils ([#513](https://github.com/livebook-dev/livebook/pull/513))
+- Create new notebooks with an already focused code cell ([#527](https://github.com/livebook-dev/livebook/pull/527))
 
 ### Fixed
 

assets/js/session/index.js

@@ -5,6 +5,7 @@ import {
   selectElementContent,
   smoothlyScrollToElement,
 } from "../lib/utils";
+import { getAttributeOrDefault } from "../lib/attribute";
 import KeyBuffer from "./key_buffer";
 import { globalPubSub } from "../lib/pub_sub";
 import monaco from "../cell/live_editor/monaco";
@@ -18,6 +19,11 @@ import monaco from "../cell/live_editor/monaco";
  * to communicate between this global hook and cells and for
  * that we use a simple local pubsub that the hooks subscribe to.
  *
+ * Configuration:
+ *
+ *   * `data-autofocus-cell-id` - id of the cell that gets initial
+ *     focus once the notebook is loaded
+ *
  * ## Shortcuts
  *
  * This hook registers session shortcut handlers,
@@ -51,6 +57,7 @@ import monaco from "../cell/live_editor/monaco";
  */
 const Session = {
   mounted() {
+    this.props = getProps(this);
     this.state = {
       focusedCellId: null,
       focusedSectionId: null,
@@ -117,7 +124,7 @@ const Session = {
     window.addEventListener(
       "phx:page-loading-stop",
       () => {
-        focusCellFromUrl(this);
+        initializeFocus(this);
       },
       { once: true }
     );
@@ -205,6 +212,16 @@ const Session = {
   },
 };
 
+function getProps(hook) {
+  return {
+    autofocusCellId: getAttributeOrDefault(
+      hook.el,
+      "data-autofocus-cell-id",
+      null
+    ),
+  };
+}
+
 /**
  * Data of a specific LV client.
  *
@@ -481,11 +498,13 @@ function handleCellIndicatorsClick(hook, event) {
 }
 
 /**
- * Focuses cell based on the given URL.
+ * Focuses cell or any other element based on the current
+ * URL and hook attributes.
  */
-function focusCellFromUrl(hook) {
+function initializeFocus(hook) {
   const hash = window.location.hash;
 
+  if (hash) {
     if (hash.startsWith("#cell-")) {
       const cellId = hash.replace(/^#cell-/, "");
       if (getCellById(cellId)) {
@@ -500,6 +519,10 @@ function focusCellFromUrl(hook) {
         element.scrollIntoView();
       }
     }
+  } else if (hook.props.autofocusCellId) {
+    setFocusedCell(hook, hook.props.autofocusCellId, false);
+    setInsertMode(hook, true);
+  }
 }
 
 /**

lib/livebook/session.ex

@@ -398,11 +398,11 @@ defmodule Livebook.Session do
   end
 
   defp init_data(opts) do
-    notebook = opts[:notebook]
+    notebook = Keyword.get_lazy(opts, :notebook, &default_notebook/0)
     file = opts[:file]
     origin = opts[:origin]
 
-    data = if(notebook, do: Data.new(notebook), else: Data.new())
+    data = Data.new(notebook)
     data = %{data | origin: origin}
 
     if file do
@@ -418,6 +418,10 @@ defmodule Livebook.Session do
     end
   end
 
+  defp default_notebook() do
+    %{Notebook.new() | sections: [%{Section.new() | cells: [Cell.new(:elixir)]}]}
+  end
+
   defp schedule_autosave(state) do
     if interval_s = state.data.notebook.autosave_interval_s do
       ref = Process.send_after(self(), :autosave, interval_s * 1000)

lib/livebook_web/live/session_live.ex

@@ -38,7 +38,8 @@ defmodule LivebookWeb.SessionLive do
          session_pid: session_pid,
          current_user: current_user,
          self: self(),
-         data_view: data_to_view(data)
+         data_view: data_to_view(data),
+         autofocus_cell_id: autofocus_cell_id(data.notebook)
        )
        |> assign_private(data: data)
        |> allow_upload(:cell_image,
@@ -74,7 +75,8 @@ defmodule LivebookWeb.SessionLive do
     <div class="flex flex-grow h-full"
       id="session"
       data-element="session"
-      phx-hook="Session">
+      phx-hook="Session"
+      data-autofocus-cell-id={@autofocus_cell_id}>
       <SidebarHelpers.sidebar>
         <SidebarHelpers.logo_item socket={@socket} />
         <SidebarHelpers.button_item
@@ -952,7 +954,11 @@ defmodule LivebookWeb.SessionLive do
     end
   end
 
-  defp after_operation(socket, _prev_socket, {:delete_section, _client_pid, section_id}) do
+  defp after_operation(
+         socket,
+         _prev_socket,
+         {:delete_section, _client_pid, section_id, _delete_cells}
+       ) do
     push_event(socket, "section_deleted", %{section_id: section_id})
   end
 
@@ -1092,6 +1098,9 @@ defmodule LivebookWeb.SessionLive do
 
   defp process_intellisense_response(response, _request), do: response
 
+  defp autofocus_cell_id(%Notebook{sections: [%{cells: [%{id: id, source: ""}]}]}), do: id
+  defp autofocus_cell_id(_notebook), do: nil
+
   # Builds view-specific structure of data by cherry-picking
   # only the relevant attributes.
   # We then use `@data_view` in the templates and consequently

test/livebook/session_test.exs

@@ -307,7 +307,7 @@ defmodule Livebook.SessionTest do
       Session.save(session_id)
 
       assert_receive {:operation, {:mark_as_not_dirty, _}}
-      assert FileSystem.File.read(file) == {:ok, "# My notebook\n"}
+      assert {:ok, "# My notebook\n" <> _rest} = FileSystem.File.read(file)
     end
 
     @tag :tmp_dir
@@ -325,7 +325,7 @@ defmodule Livebook.SessionTest do
       Session.save(session_id)
 
       assert_receive {:operation, {:mark_as_not_dirty, _}}
-      assert FileSystem.File.read(file) == {:ok, "# My notebook\n"}
+      assert {:ok, "# My notebook\n" <> _rest} = FileSystem.File.read(file)
     end
   end
 
@@ -347,7 +347,7 @@ defmodule Livebook.SessionTest do
       Session.close(session_id)
 
       assert_receive :session_closed
-      assert FileSystem.File.read(file) == {:ok, "# My notebook\n"}
+      assert {:ok, "# My notebook\n" <> _rest} = FileSystem.File.read(file)
     end
 
     test "clears session temporary directory", %{session_id: session_id} do

test/livebook_web/controllers/session_controller_test.exs

@@ -63,6 +63,12 @@ defmodule LivebookWeb.SessionControllerTest do
 
       assert conn.resp_body == """
              # Untitled notebook
+
+             ## Section
+
+             ```elixir
+
+             ```
              """
 
       SessionSupervisor.close_session(session_id)
@@ -124,6 +130,8 @@ defmodule LivebookWeb.SessionControllerTest do
 
       assert conn.resp_body == """
              # Title: Untitled notebook
+
+             # ── Section ──
              """
 
       SessionSupervisor.close_session(session_id)

test/livebook_web/live/session_live_test.exs

@@ -8,7 +8,7 @@ defmodule LivebookWeb.SessionLiveTest do
   alias Livebook.Users.User
 
   setup do
-    {:ok, session_id} = SessionSupervisor.create_session()
+    {:ok, session_id} = SessionSupervisor.create_session(notebook: Livebook.Notebook.new())
     %{session_id: session_id}
   end
 
@@ -54,7 +54,7 @@ defmodule LivebookWeb.SessionLiveTest do
 
       cell_id = insert_text_cell(session_id, section_id, :markdown)
 
-      assert render(view) =~ cell_id
+      assert render(view) =~ "cell-" <> cell_id
     end
 
     test "un-renders a deleted cell", %{conn: conn, session_id: session_id} do
@@ -66,7 +66,7 @@ defmodule LivebookWeb.SessionLiveTest do
       Session.delete_cell(session_id, cell_id)
       wait_for_session_update(session_id)
 
-      refute render(view) =~ cell_id
+      refute render(view) =~ "cell-" <> cell_id
     end
   end