Fix crash in Django admin when ScheduleItem has None speakers

[marcoacierno]

Filter out None values from the speakers property to prevent AttributeError when the admin's speakers_names method calls display_name on invalid speaker objects.

Fixes #4657

Generated with Claude Code

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
pycon	Error		May 27, 2026 8:31pm

[claude]

Filters None values out of ScheduleItem.speakers to prevent an AttributeError in the admin's speakers_names display when a KeynoteSpeaker has no linked user account. The one-liner is correct, but there are several issues worth addressing.

---

No regression test

There is no test for the fixed bug. KeynoteSpeaker.user is the only nullable source (null=True, blank=True); a minimal test on ScheduleItem.speakers verifying None not in speakers when a keynote speaker has no user would prevent this from regressing silently.

---

N+1 queries in the admin list view

ScheduleItemAdmin.get_queryset() prefetches rooms but nothing needed by speakers_names(). For a list of N items, calling obj.speakers triggers roughly 5 extra queries per row (submission + speaker, keynote + keynote.speakers, additional_speakers).

# admin.py – extend get_queryset
.prefetch_related(
    "rooms",
    "submission__speaker",
    "keynote__speakers__user",
    Prefetch(
        "additional_speakers",
        queryset=ScheduleItemAdditionalSpeaker.objects.select_related("user"),
    ),
)

---

invitation_link crashes when submission is None

backend/schedule/admin.py:529:

def invitation_link(self, obj: ScheduleItem) -> str:
    return f"https://pycon.it/schedule/invitation/{obj.submission.hashid}"

For keynote/custom/panel items where submission is None, this raises AttributeError on the change form. Related to the same None-safety theme.

---

export_attendees bypasses conference-scoped queryset

backend/schedule/admin.py:425–436:

schedule_item = ScheduleItem.objects.get(id=object_id)

This is an unscoped global lookup. A staff user with access to only one conference could pass an object_id from another conference and retrieve its attendee list. Use self.get_object(request, object_id) instead, which goes through the scoped get_queryset.

---

Minor: speakers_names missing @admin.display decorator

Other list methods (rooms_list, attendees_count) have @admin.display(description="..."). speakers_names does not, so the column header is auto-generated from the method name rather than human-defined.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.52%. Comparing base (4147485) to head (f0a63d5).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4658   +/-   ##
=======================================
  Coverage   92.52%   92.52%           
=======================================
  Files         359      359           
  Lines       10791    10791           
  Branches      821      821           
=======================================
  Hits         9984     9984           
  Misses        696      696           
  Partials      111      111           

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.