Fix deserialization of empty grids

Signed-off-by: martinRenou <[email protected]>

Author: martinRenou

js/datagrid.ts

@@ -84,13 +84,22 @@ function serialize_data(data: DataSource, manager: any): any {
 function deserialize_data(data: any, manager: any): DataSource {
   const deserialized_data: any = {};
   for (const column of Object.keys(data.data)) {
+    deserialized_data[column] = [];
+
+    if (Array.isArray(data.data[column])) {
+      deserialized_data[column] = data.data[column];
+      continue;
+    }
+
     if (data.data[column].type == 'raw') {
       deserialized_data[column] = unpack_raw_data(data.data[column].value);
     } else {
-      deserialized_data[column] = array_or_json_serializer.deserialize(
-        data.data[column],
-        manager,
-      );
+      if (data.data[column].value.length !== 0) {
+        deserialized_data[column] = array_or_json_serializer.deserialize(
+          data.data[column],
+          manager,
+        );
+      }
     }
   }
   return new DataSource(deserialized_data, data.fields, data.schema, true);

ui-tests-ipw8/tests/ipydatagrid.test.ts-snapshots/dark-empty-ipynb-cell-0-linux.png

@@ -0,0 +1,42 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "c8271791-1c8f-4b79-b105-f57576533aaa",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from ipydatagrid import DataGrid, TextRenderer, BarRenderer, Expr, ImageRenderer\n",
+    "\n",
+    "import pandas as pd\n",
+    "\n",
+    "columns = [\"a\", \"b\", \"c\"]\n",
+    "\n",
+    "df = pd.DataFrame(dict(zip(columns, len(columns) * [[]])))\n",
+    "DataGrid(df)"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3 (ipykernel)",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.12.3"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}