Make the database stuff more abstract

But only a bit

src/invidious_exporter/database.py

@@ -21,6 +21,15 @@ async def get_playlists(connection: Connection, user_email: str) -> list[Playlis
             p.index, p.title, p.description, p.privacy;
     """
 
+    return create_playlists(await connection.fetch(sql, user_email))
+
+async def export_user(connection: Connection, user_email: str) -> InvidiousJsonDataExport:
+    data = await connection.fetchrow("SELECT subscriptions, watched, preferences FROM users WHERE email = $1", user_email)
+    playlists = await get_playlists(connection, user_email)
+
+    return create_json_data_export(data, playlists)
+
+def create_playlists(rows):
     return [
         Playlist(
             title=row['title'],
@@ -28,17 +37,13 @@ async def get_playlists(connection: Connection, user_email: str) -> list[Playlis
             privacy=PlaylistPrivacy[row['privacy']],
             video_ids=row['video_ids'] or []
         )
-        for row in await connection.fetch(sql, user_email)
+        for row in rows
     ]
 
-async def export_user(connection: Connection, user_email: str) -> InvidiousJsonDataExport:
-    data = await connection.fetchrow("SELECT subscriptions, watched, preferences FROM users WHERE email = $1", user_email)
-    
-    subscribed_channels_ids = data['subscriptions']
-    watched_videos_ids = data['watched']
-    user_preferences = json.loads(data['preferences'])
-
-    playlists = await get_playlists(connection, user_email)
+def create_json_data_export(row, playlists):
+    subscribed_channels_ids = row['subscriptions']
+    watched_videos_ids = row['watched']
+    user_preferences = json.loads(row['preferences'])
 
     data_export = InvidiousJsonDataExport(
         subscriptions = [Channel(id=c_id) for c_id in subscribed_channels_ids],