Do not use the restorer on tree view, and do not restore widgets from trackers

Author: brichet

packages/application-extension/src/index.ts

@@ -9,7 +9,6 @@ import {
   JupyterFrontEnd,
   JupyterFrontEndPlugin,
   JupyterLab,
-  LayoutRestorer,
 } from '@jupyterlab/application';
 
 import {
@@ -20,7 +19,6 @@ import {
   IToolbarWidgetRegistry,
   IWindowResolver,
   showErrorMessage,
-  WindowResolver,
 } from '@jupyterlab/apputils';
 
 import { ConsolePanel } from '@jupyterlab/console';
@@ -57,8 +55,11 @@ import {
   SidePanelPalette,
   INotebookPathOpener,
   defaultNotebookPathOpener,
+  NotebookLayoutRestorer,
 } from '@jupyter-notebook/application';
 
+import { NotebookTreeWidget } from '@jupyter-notebook/tree';
+
 import { jupyterIcon } from '@jupyter-notebook/ui-components';
 
 import { PromiseDelegate } from '@lumino/coreutils';
@@ -196,23 +197,32 @@ const layoutRestorer: JupyterFrontEndPlugin<ILayoutRestorer | null> = {
     notebookShell: INotebookShell | null
   ) => {
     if (!notebookShell) {
-      console.log('No layout for this view');
       return null;
     }
-
     const first = app.started;
     const registry = app.commands;
 
-    const restorer = new LayoutRestorer({
+    const restorer = new NotebookLayoutRestorer({
       connector: state,
       first,
       registry,
     });
 
-    // Restore the layout.
-    void notebookShell.restoreLayout(restorer, {}).then(() => {
-      notebookShell.layoutModified.connect(() => {
-        void restorer.save(notebookShell.saveLayout());
+    // Restore the layout when the main widget is loaded.
+    void notebookShell.mainWidgetLoaded.then(() => {
+      // Whether to actually restore the layout or not (not for the tree view).
+      const restoreLayout = !(
+        notebookShell.currentWidget instanceof NotebookTreeWidget
+      );
+
+      // Call the restorer even if the layout must not be restored, to resolve the
+      // promise.
+      void notebookShell.restoreLayout(restorer, restoreLayout).then(() => {
+        if (restoreLayout) {
+          notebookShell.layoutModified.connect(() => {
+            void restorer.save(notebookShell.saveLayout());
+          });
+        }
       });
     });
 
@@ -519,15 +529,10 @@ const resolver: JupyterFrontEndPlugin<IWindowResolver> = {
   description: 'Provides the window name resolver.',
   autoStart: true,
   provides: IWindowResolver,
-  requires: [JupyterFrontEnd.IPaths, IRouter],
-  activate: async (
-    app: JupyterFrontEnd,
-    paths: JupyterFrontEnd.IPaths,
-    router: IRouter
-  ) => {
-    const solver = new WindowResolver();
-    (solver as any)._name = 'nb-default';
-    return solver;
+  activate: async (app: JupyterFrontEnd) => {
+    return {
+      name: 'nb-default',
+    };
   },
 };
 

packages/application/src/index.ts

@@ -3,6 +3,7 @@
 
 export * from './app';
 export * from './shell';
+export * from './layoutrestorer';
 export * from './panelhandler';
 export * from './pathopener';
 export * from './tokens';

packages/application/src/layoutrestorer.ts

@@ -0,0 +1,14 @@
+import { LayoutRestorer } from '@jupyterlab/application';
+import { WidgetTracker } from '@jupyterlab/apputils';
+import { IRestorer } from '@jupyterlab/statedb';
+import { Widget } from '@lumino/widgets';
+
+export class NotebookLayoutRestorer extends LayoutRestorer {
+  // Override the restore function, that adds widget tracker state to the restorer.
+  async restore(
+    tracker: WidgetTracker,
+    options: IRestorer.IOptions<Widget>
+  ): Promise<any> {
+    // no-op as we don't want to restore widgets, only the layout.
+  }
+}

packages/application/src/shell.ts

@@ -267,6 +267,13 @@ export class NotebookShell extends Widget implements JupyterFrontEnd.IShell {
     return this._layoutModified;
   }
 
+  /**
+   * Promise that resolves when the main widget is loaded.
+   */
+  get mainWidgetLoaded(): Promise<void> {
+    return this._mainWidgetLoaded.promise;
+  }
+
   /**
    * Promise that resolves when the main widget is loaded and the layout restored.
    */
@@ -495,10 +502,14 @@ export class NotebookShell extends Widget implements JupyterFrontEnd.IShell {
    */
   async restoreLayout(
     layoutRestorer: LayoutRestorer,
-    configuration: {
-      [m: string]: INotebookShell.IUserLayout;
-    } = {}
+    restore: boolean
   ): Promise<void> {
+    // If no restoration is expected for the current view, resolve the promise.
+    if (!restore) {
+      this._restored.resolve();
+      return;
+    }
+
     // Get the layout from the restorer
     const layout = await layoutRestorer.fetch();
 

packages/docmanager-extension/src/index.ts

@@ -45,10 +45,7 @@ const opener: JupyterFrontEndPlugin<IDocumentWidgetOpener> = {
         options?: DocumentRegistry.IOpenOptions
       ) {
         const widgetName = options?.type ?? '';
-
-        // Should we consider ref === null or ref === undefined as different the '_noref' ?
-        const ref = options?.ref ?? '_noref';
-
+        const ref = options?.ref;
         // check if there is an setting override and if it would add the widget in the main area
         const userLayoutArea = notebookShell?.userLayout?.[widgetName]?.area;