Location endpoint raises internal server error when default translation is not public

[timobrembeck]

Describe the Bug

When a region creates a location which is a draft in the default language, but public in other languages, the location API returns an internal server error

Steps to Reproduce

1. Create location as draft in default language
2. Publish location in different language
3. Access location API (e.g. https://admin.integreat-app.de/api/maintal/en/locations/)
4. See error

Expected Behavior

1. It should not be possible to publish a POI translation in a different language when the default translation is not public
2. In case this inconsistent state is reached anyway, the API should not deliver those POIs.

Actual Behavior

The database inconsistency causes an internal server error

Additional Information

Traceback

Feb 23 15:52:35 ERROR   django.request - 500 Internal Server Error: /maintal/en/wp-json/extensions/v3/locations/?on_map=1
Traceback (most recent call last):
File "/opt/integreat-cms/.venv/lib/python3.9/site-packages/django/core/handlers/exception.py", line 47, in inner
  response = get_response(request)
File "/opt/integreat-cms/.venv/lib/python3.9/site-packages/django/core/handlers/base.py", line 181, in _get_response
  response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/opt/integreat-cms/.venv/lib/python3.9/site-packages/integreat_cms/api/decorators.py", line 124, in wrap
  return function(request, *args, **kwargs)
File "/opt/integreat-cms/.venv/lib/python3.9/site-packages/integreat_cms/api/v3/locations.py", line 149, in locations
  result.append(transform_poi_translation(translation))
File "/opt/integreat-cms/.venv/lib/python3.9/site-packages/integreat_cms/api/v3/locations.py", line 75, in transform_poi_translation
  "title": poi.default_public_translation.title,
AttributeError: 'NoneType' object has no attribute 'title'

This is a regression from 70630ff (#2057).

[seluianova]

It should not be possible to publish a POI translation in a different language when the default translation is not public

@timoludwig do you think it's okay if the translation is saved as a draft with a warning?
Like "The translation has not been published, because the default translation for this page is not public"

Or "Publish" button should be disabled/hidden at all?

Do we want to implement the same for Events and Pages for consistency?

[timobrembeck]

@timoludwig do you think it's okay if the translation is saved as a draft with a warning? Like "The translation has not been published, because the default translation for this page is not public"

Or "Publish" button should be disabled/hidden at all?

Both is fine, probably a disabled publish button would be the most helpful (together with a small explanation text on hovering the button)?

Do we want to implement the same for Events and POIs for consistency?

I don't think so, for pages and events there might be content which is only relevant for a target group of a specific language, and thus region managers sometimes deliberately publish something only in one language. Just for locations this doesn't work because of the title...