Avoid saving/restoring document widget

Author: brichet

packages/application-extension/src/index.ts

@@ -2,13 +2,15 @@
 // Distributed under the terms of the Modified BSD License.
 
 import {
+  ILabShell,
   ILabStatus,
   ILayoutRestorer,
   IRouter,
   ITreePathUpdater,
   JupyterFrontEnd,
   JupyterFrontEndPlugin,
   JupyterLab,
+  LayoutRestorer,
 } from '@jupyterlab/application';
 
 import {
@@ -54,7 +56,7 @@ import {
   SidePanelPalette,
   INotebookPathOpener,
   defaultNotebookPathOpener,
-  NotebookLayoutRestorer,
+  NotebookStateDB,
 } from '@jupyter-notebook/application';
 
 import { jupyterIcon } from '@jupyter-notebook/ui-components';
@@ -216,7 +218,7 @@ const layoutRestorer: JupyterFrontEndPlugin<ILayoutRestorer | null> = {
     const first = app.started;
     const registry = app.commands;
 
-    const restorer = new NotebookLayoutRestorer({
+    const restorer = new LayoutRestorer({
       connector: state,
       first,
       registry,
@@ -228,7 +230,7 @@ const layoutRestorer: JupyterFrontEndPlugin<ILayoutRestorer | null> = {
       // promise.
       void notebookShell.restoreLayout(restorer).then(() => {
         notebookShell.layoutModified.connect(() => {
-          void restorer.save(notebookShell.saveLayout());
+          void restorer.save(notebookShell.saveLayout() as ILabShell.ILayout);
         });
       });
     });
@@ -623,7 +625,7 @@ const state: JupyterFrontEndPlugin<IStateDB> = {
     const { workspaces } = serviceManager;
     const workspace = PageConfig.getOption('notebookPage');
     const transform = new PromiseDelegate<StateDB.DataTransform>();
-    const db = new StateDB({ transform: transform.promise });
+    const db = new NotebookStateDB({ transform: transform.promise });
     const save = new Debouncer(async () => {
       const id = workspace;
       const metadata = { id };

packages/application/src/index.ts

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

packages/application/src/layoutrestorer.ts

@@ -0,0 +1,33 @@
+import { StateDB } from '@jupyterlab/statedb';
+import {
+  ReadonlyPartialJSONObject,
+  ReadonlyPartialJSONValue,
+} from '@lumino/coreutils';
+
+/**
+ * The default concrete implementation of a state database.
+ */
+export class NotebookStateDB extends StateDB<ReadonlyPartialJSONValue> {
+  constructor(options: StateDB.IOptions<ReadonlyPartialJSONValue> = {}) {
+    super(options);
+    this._originalSave = super.save.bind(this);
+  }
+
+  // Override the save method to avoid saving the document widget (in main area).
+  // NOTE: restoring a document widget open a new tab.
+  async save(id: string, value: ReadonlyPartialJSONValue): Promise<void> {
+    const data = (value as ReadonlyPartialJSONObject)[
+      'data'
+    ] as ReadonlyPartialJSONObject;
+
+    // If data.path and data.factory are defined, the widget is a document widget, that
+    // we don't want to save in the layout restoration.
+    if (data?.['path'] && data?.['factory']) {
+      return;
+    } else {
+      this._originalSave(id, value);
+    }
+  }
+
+  private _originalSave: typeof StateDB.prototype.save;
+}