Add support for async model creation

src/model.ts

@@ -1,5 +1,5 @@
 import { MapChange } from '@jupyter/ydoc';
-import { JSONExt, JSONObject } from '@lumino/coreutils';
+import { JSONExt, JSONObject, PromiseDelegate } from '@lumino/coreutils';
 import { ISignal, Signal } from '@lumino/signaling';
 import * as Y from 'yjs';
 
@@ -8,8 +8,9 @@ import { IJupyterYDoc, IJupyterYModel } from './types';
 export class JupyterYModel implements IJupyterYModel {
   constructor(commMetadata: { [key: string]: any }) {
     this._yModelName = commMetadata.ymodel_name;
-    const ydoc = this.ydocFactory(commMetadata);
-    this._sharedModel = new JupyterYDoc(commMetadata, ydoc);
+    this.initialize(commMetadata).then(() => {
+      this._ready.resolve();
+    });
   }
 
   get yModelName(): string {
@@ -20,6 +21,18 @@ export class JupyterYModel implements IJupyterYModel {
     return this._sharedModel;
   }
 
+  get ydoc(): Y.Doc {
+    return this._ydoc;
+  }
+
+  protected set sharedModel(value: IJupyterYDoc) {
+    this._sharedModel = value;
+  }
+
+  protected set ydoc(value: Y.Doc) {
+    this._ydoc = value;
+  }
+
   get sharedAttrsChanged(): ISignal<IJupyterYDoc, MapChange> {
     return this.sharedModel.attrsChanged;
   }
@@ -32,6 +45,15 @@ export class JupyterYModel implements IJupyterYModel {
     return this._isDisposed;
   }
 
+  get ready(): Promise<void> {
+    return this._ready.promise;
+  }
+
+  protected async initialize(commMetadata: { [key: string]: any }) {
+    this.ydoc = this.ydocFactory(commMetadata);
+    this.sharedModel = new JupyterYDoc(commMetadata, this._ydoc);
+  }
+
   ydocFactory(commMetadata: { [key: string]: any }): Y.Doc {
     return new Y.Doc();
   }
@@ -54,11 +76,15 @@ export class JupyterYModel implements IJupyterYModel {
     this.sharedModel.removeAttr(key);
   }
 
+  private _ydoc: Y.Doc;
+
   private _yModelName: string;
   private _sharedModel: IJupyterYDoc;
 
   private _isDisposed = false;
 
+  private _ready: PromiseDelegate<void> = new PromiseDelegate<void>();
+
   private _disposed = new Signal<this, void>(this);
 }
 

src/notebookrenderer/view.ts

@@ -30,13 +30,17 @@ export class JupyterYWidget extends Widget implements IRenderMime.IRenderer {
     this._yModel?.dispose();
     super.dispose();
   }
+
   async renderModel(mimeModel: IRenderMime.IMimeModel): Promise<void> {
     const modelId = mimeModel.data[this._mimeType]!['model_id'];
 
     this._yModel = this._modelFactory.getYModel(modelId);
     if (!this._yModel) {
       return;
     }
+
+    await this._yModel.ready;
+
     this._ywidget = this._modelFactory.createYWidget(modelId, this.node);
   }
 

src/notebookrenderer/widgetManager.ts

@@ -69,6 +69,8 @@ export class WidgetModelRegistry implements IJupyterYWidgetModelRegistry {
     );
     const yModel: IJupyterYModel = new yModelFactory(msg.metadata);
 
+    await yModel.ready;
+
     new YCommProvider({
       comm,
       ydoc: yModel.sharedModel.ydoc

src/types.ts

@@ -30,4 +30,6 @@ export interface IJupyterYModel extends IDisposable {
   sharedAttrsChanged: ISignal<IJupyterYDoc, MapChange>;
 
   disposed: ISignal<any, void>;
+
+  ready: Promise<void>;
 }