fix chapterData updates for posts

Author: ceolinwill

functions/src/chapters/onUpdate/__tests__/updatePosts.spec.ts

@@ -50,9 +50,7 @@ test('update all posts', async (done) => {
   };
   const wrapped = testEnv.wrap(onUpdateChapterUpdatePosts);
   const req = await wrapped(change);
-  const payload = {
-    'chapterData.chapterId': { ...newData, id: 'chapterId' },
-  };
+  const payload = { chapterData: { ...newData, id: 'chapterId' } };
 
   expect(req).toBe('updated');
   expect(db.doc).toHaveBeenCalledWith('posts/ex1');

functions/src/chapters/onUpdate/updatePosts.ts

@@ -34,9 +34,7 @@ export const onUpdateChapterUpdatePosts = functions.firestore
         id,
         title: after.title,
       };
-      batch.update(ref, {
-        [`chapterData.${id}`]: summary,
-      });
+      batch.update(ref, { chapterData: summary });
     });
 
     return batch.commit();