librephotos-backend start error: TypeError: 'type' object is not subscriptable

[cahaya42]

To install librephotos, I made a fresh install of Ubuntu 20.04.5 LTS in VirtualBox.
I solved a couple of issues (postgresql user & secret.key) but now I'm stuck on TypeError: 'type' object is not subscriptable error.

# service librephotos-backend status
● librephotos-backend.service - librephotos-backend
     Loaded: loaded (/etc/systemd/system/librephotos-backend.service; enabled; vendor preset: enabled)
     Active: active (running) since Thu 2023-02-09 15:57:48 ACDT; 5h 57min ago
       Docs: https://github.com/LibrePhotos/librephotos
   Main PID: 1038 (bash)
      Tasks: 7 (limit: 38428)
     Memory: 495.2M
     CGroup: /system.slice/librephotos-backend.service
             ├─1038 bash /usr/lib/librephotos/bin/librephotos-backend
             ├─1614 /usr/bin/python3 /usr/bin/gunicorn --workers=2 --worker-class=gevent --timeout 3600 --bind 127.0.0.1:8001 --log-level=info ownphotos.wsgi
             ├─1615 tee /var/log/librephotos//gunicorn_django.log
             ├─1617 /usr/bin/python3 /usr/bin/gunicorn --workers=2 --worker-class=gevent --timeout 3600 --bind 127.0.0.1:8001 --log-level=info ownphotos.wsgi
             └─1618 /usr/bin/python3 /usr/bin/gunicorn --workers=2 --worker-class=gevent --timeout 3600 --bind 127.0.0.1:8001 --log-level=info ownphotos.wsgi

Feb 09 16:16:54 photos librephotos-backend[1615]:     from api.serializers.album_auto import AlbumAutoListSerializer, AlbumAutoSerializer
Feb 09 16:16:54 photos librephotos-backend[1615]:   File "/usr/lib/librephotos/backend/api/serializers/album_auto.py", line 4, in <module>
Feb 09 16:16:54 photos librephotos-backend[1615]:     from api.serializers.person import PersonSerializer
Feb 09 16:16:54 photos librephotos-backend[1615]:   File "/usr/lib/librephotos/backend/api/serializers/person.py", line 5, in <module>
Feb 09 16:16:54 photos librephotos-backend[1615]:     from api.serializers.photos import GroupedPhotosSerializer
Feb 09 16:16:54 photos librephotos-backend[1615]:   File "/usr/lib/librephotos/backend/api/serializers/photos.py", line 133, in <module>
Feb 09 16:16:54 photos librephotos-backend[1615]:     class PhotoSerializer(serializers.ModelSerializer):
Feb 09 16:16:54 photos librephotos-backend[1615]:   File "/usr/lib/librephotos/backend/api/serializers/photos.py", line 209, in PhotoSerializer
Feb 09 16:16:54 photos librephotos-backend[1615]:     def get_image_path(self, obj) -> list[str]:
Feb 09 16:16:54 photos librephotos-backend[1615]: TypeError: 'type' object is not subscriptable

The same error occurs in the /var/log/librephotos/gunicorn_django.log file when launch the site for the first time in a web browser.

2023-02-09 05:46:54 +0000] [1617] [ERROR] Error handling request /api/firsttimesetup/
Traceback (most recent call last):
  File "/usr/lib/librephotos/.local/lib/python3.8/site-packages/django/core/handlers/exception.py", line 47, in inner
    response = get_response(request)
  File "/usr/lib/librephotos/.local/lib/python3.8/site-packages/django/core/handlers/base.py", line 167, in _get_response
    callback, callback_args, callback_kwargs = self.resolve_request(request)
  File "/usr/lib/librephotos/.local/lib/python3.8/site-packages/django/core/handlers/base.py", line 290, in resolve_request
    resolver_match = resolver.resolve(request.path_info)
  File "/usr/lib/librephotos/.local/lib/python3.8/site-packages/django/urls/resolvers.py", line 549, in resolve
    for pattern in self.url_patterns:
  File "/usr/lib/librephotos/.local/lib/python3.8/site-packages/django/utils/functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/usr/lib/librephotos/.local/lib/python3.8/site-packages/django/urls/resolvers.py", line 593, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "/usr/lib/librephotos/.local/lib/python3.8/site-packages/django/utils/functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/usr/lib/librephotos/.local/lib/python3.8/site-packages/django/urls/resolvers.py", line 586, in urlconf_module
    return import_module(self.urlconf_name)
  File "/usr/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 848, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/usr/lib/librephotos/backend/ownphotos/urls.py", line 30, in <module>
    from api.views import (
  File "/usr/lib/librephotos/backend/api/views/album_auto.py", line 11, in <module>
    from api.serializers.album_auto import AlbumAutoListSerializer, AlbumAutoSerializer
  File "/usr/lib/librephotos/backend/api/serializers/album_auto.py", line 4, in <module>
    from api.serializers.person import PersonSerializer
  File "/usr/lib/librephotos/backend/api/serializers/person.py", line 5, in <module>
    from api.serializers.photos import GroupedPhotosSerializer
  File "/usr/lib/librephotos/backend/api/serializers/photos.py", line 133, in <module>
    class PhotoSerializer(serializers.ModelSerializer):
  File "/usr/lib/librephotos/backend/api/serializers/photos.py", line 209, in PhotoSerializer
    def get_image_path(self, obj) -> list[str]:
TypeError: 'type' object is not subscriptable

Any suggestions on how to investigate this further?

[derneuere]

This is probably an issue with the python version. Should be 3.9 or higher.

[cahaya42]

The version of python that ships with Ubuntu 20.04 LTS is 3.8.2. Currently on my system I have:

 python3 --version
Python 3.8.10

[derneuere]

Alright, we have found the issue! I would recommend upgrading to a newer LTS version like Jammy Jellyfish 22.04. If you don't want to, we could create an issue for that instead. Maybe there is a workaround for it.

[cahaya42]

Since it was a new VM dedicated to LibrePhotos, I've tossed it away and started afresh with Ubuntu 22.04.1 LTS.
After making the changes described in issue #54 and issue #55. The installation ran successfully, the services started and the first setup page was displayed. 😄

Based on this I would recommend:

1. Python 3.9 is added as a per-requisite (and optionally a check added to the script)
2. Ubuntu 22.04 LTS is recommended over 20.04