Auto format code when save the notebook (#195)

* Format all cells when save file

* Handling formatOnSave setting

Author: simamumu

schema/settings.json

@@ -226,6 +226,10 @@
             },
             "additionalProperties": false,
             "type": "object"
+        },
+        "formatOnSave": {
+            "additionalProperties": false,
+            "type": "boolean"
         }
     },
     "properties": {
@@ -291,6 +295,12 @@
             "description": "Config to be passed into styler's style_text function call.",
             "$ref": "#/definitions/styler",
             "default": {}
+        },
+        "formatOnSave": {
+            "title": "Auto format config",
+            "description": "Auto format code when save the notebook.",
+            "$ref": "#/definitions/formatOnSave",
+            "default": false
         }
     },
     "additionalProperties": false,

src/index.ts

@@ -96,11 +96,20 @@ class JupyterLabCodeFormatter
       this.app.commands.label(Constants.FORMAT_ALL_COMMAND),
       button
     );
+
+    context.saveState.connect(this.onSave, this);
+
     return new DisposableDelegate(() => {
       button.dispose();
     });
   }
 
+  private async onSave(context: DocumentRegistry.IContext<INotebookModel>, state: DocumentRegistry.SaveState) {
+    if (state == 'started' && this.config.formatOnSave) {
+      await this.notebookCodeFormatter.formatAllCodeCells(this.config);
+    }
+  }
+
   private setupWidgetExtension() {
     this.app.docRegistry.addWidgetExtension('Notebook', this);
   }