Only sort keys if id is inserted

src/clean_notebook/clean.py

@@ -33,7 +33,7 @@ def clean_single_notebook(
     nb = json.loads(raw)
     set_id = _check_set_id(nb)
 
-    cleaned = False
+    cleaned, sort_keys = False, False
     for cell in nb["cells"].copy():
         cleaned |= _update_value(cell, "outputs", [])
         cleaned |= _update_value(cell, "execution_count", None)
@@ -45,6 +45,7 @@ def clean_single_notebook(
             del cell["attachments"]
             cleaned = True
         if set_id and cell.get("id") is None:
+            sort_keys |= "id" not in cell
             cell["id"] = str(uuid.uuid4())
             cleaned = True
 
@@ -57,7 +58,7 @@ def clean_single_notebook(
 
     if cleaned and not dryrun:
         with open(file, "w", encoding="utf8", newline=newline) as f:
-            json.dump(nb, f, indent=1, ensure_ascii=False, sort_keys=True)
+            json.dump(nb, f, indent=1, ensure_ascii=False, sort_keys=sort_keys)
             f.write(newline)  # empty line at the end of the file
         print(f"Cleaned notebook: {file}")
     elif cleaned:

tests/data/clean_colab.ipynb

@@ -1,4 +1,12 @@
 {
+ "nbformat": 4,
+ "nbformat_minor": 0,
+ "metadata": {
+  "language_info": {
+   "name": "python",
+   "pygments_lexer": "ipython3"
+  }
+ },
  "cells": [
   {
    "cell_type": "code",
@@ -13,29 +21,21 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
-   "metadata": {},
-   "outputs": [],
    "source": [
     "print(\"saved from colab\")"
-   ]
+   ],
+   "metadata": {},
+   "execution_count": null,
+   "outputs": []
   },
   {
    "cell_type": "code",
-   "execution_count": null,
-   "metadata": {},
-   "outputs": [],
    "source": [
     ""
-   ]
-  }
- ],
- "metadata": {
-  "language_info": {
-   "name": "python",
-   "pygments_lexer": "ipython3"
+   ],
+   "metadata": {},
+   "execution_count": null,
+   "outputs": []
   }
- },
- "nbformat": 4,
- "nbformat_minor": 0
+ ]
 }