prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  Atendee list bug when adding or removing users
  <!-- If this is a security issue or information leakage (having access to something you (probably) shouldn't), please send an email rather than opening a public issue. -->
  
  ## What kind of an issue is this?
  
  - Bug report
  
  
  ## What is the expected behaviour?
  It should look normal where every box and number is under its corresponding column. It should just look normal. Even if we remove users or add users through the dashboard, nothing should change.
  
  ![screenshot from 2018-09-25 21-07-06](https://user-images.githubusercontent.com/41551253/46037365-3b160c80-c108-11e8-9de5-91ef62505aeb.png)
  
  
  ## What is the current behaviour?
  If you remove or add a user through the dashboard menu at the attendee list it will look like the screenshot above. We have randomly two boxes, the x for removing users is all the way to the right and the text "none" is occupying the remove column. If you refresh the site it will go back to expected behaviour, its only after deleteing/adding a user
  
  ![screenshot from 2018-09-25 20-00-23](https://user-images.githubusercontent.com/41551253/46037343-29346980-c108-11e8-99e1-c69b77695d3e.png)
  <!-- if this is a bug report -->
  
  
  ## How do you reproduce this problem? 
  Remove or add a user to the attendee list manually.
  <!-- if this is a bug report -->
  <!-- provide steps to reproduce this problem, preferably in a bullet point list -->
  1. go to the attendee list
  2. Add a user by writing their name OR remove a user from the list
  ## Other information
  
  This might be a bug which I didn't catch when I added "year of study" to the attendee list. I'm not sure if this was an issue before, but since it hasn't been brought up I will assume this is a bug from that pull request of mine
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `apps/events/dashboard/utils.py`
  Content:
  ```
  1 # -*- coding: utf-8 -*-
  2 from django.urls import reverse
  3 
  4 from apps.authentication.models import OnlineUser as User
  5 from apps.events.models import Attendee, Event
  6 
  7 
  8 def _get_attendee(attendee_id):
  9     try:
  10         return Attendee.objects.get(pk=attendee_id)
  11     except Attendee.DoesNotExist:
  12         return None
  13 
  14 
  15 def event_ajax_handler(event: Event, request):
  16     action = request.POST.get('action')
  17     administrating_user = request.user
  18     attendee_id = request.POST.get('attendee_id')
  19     user_id = request.POST.get('user_id')
  20 
  21     if action == 'attended':
  22         attendee = _get_attendee(attendee_id)
  23         if not attendee:
  24             return {'message': f'Fant ingen påmeldte med oppgitt ID ({attendee_id}).', 'status': 400}
  25         return handle_attended(attendee)
  26     elif action == 'paid':
  27         attendee = _get_attendee(attendee_id)
  28         if not attendee:
  29             return {'message': f'Fant ingen påmeldte med oppgitt ID ({attendee_id}).', 'status': 400}
  30         return handle_paid(attendee)
  31     elif action == 'add_attendee':
  32         return handle_add_attendee(event, user_id)
  33     elif action == 'remove_attendee':
  34         return handle_remove_attendee(event, attendee_id, administrating_user)
  35     else:
  36         raise NotImplementedError
  37 
  38 
  39 def handle_attended(attendee: Attendee):
  40     """
  41     Toggle attending-status of an attendee between attending and not attending
  42     """
  43     attendee.attended = not attendee.attended
  44     attendee.save()
  45 
  46     return {'message': 'OK', 'status': 200}
  47 
  48 
  49 def handle_paid(attendee: Attendee):
  50     """
  51     Toggle paid status of an attendee between paid and not paid
  52     """
  53     attendee.paid = not attendee.paid
  54     attendee.save()
  55 
  56     return {'message': 'OK', 'status': 200}
  57 
  58 
  59 def _get_attendee_data(attendee_qs):
  60     attendees = []
  61 
  62     for number, a in enumerate(attendee_qs):
  63         attendees.append({
  64             'number': number + 1,
  65             'id': a.id,
  66             'first_name': a.user.first_name,
  67             'last_name': a.user.last_name,
  68             'paid': a.paid,
  69             'extras': str(a.extras),
  70             'attended': a.attended,
  71             'link': reverse('dashboard_attendee_details', kwargs={'attendee_id': a.id})
  72         })
  73 
  74     return attendees
  75 
  76 
  77 def _get_event_context(event: Event, response={}):
  78     response['attendees'] = _get_attendee_data(event.attendance_event.attending_attendees_qs)
  79     response['waitlist'] = _get_attendee_data(event.attendance_event.waitlist_qs)
  80 
  81     return response
  82 
  83 
  84 def handle_add_attendee(event: Event, user_id: int):
  85     resp = _get_event_context(event)
  86     if event.attendance_event.number_of_seats_taken >= event.attendance_event.max_capacity:
  87         if not event.attendance_event.waitlist:
  88             return {'message': f'Det er ingen ledige plasser på {event.title}.', 'status': 400, **resp}
  89 
  90     user = User.objects.filter(pk=user_id)
  91     if user.count() != 1:
  92         return {'message': f'Fant ingen bruker med oppgitt ID ({user_id}).', 'status': 400, **resp}
  93     user = user[0]
  94     if Attendee.objects.filter(user=user, event=event.attendance_event).count() != 0:
  95         return {'message': f'{user} er allerede påmeldt {event.title}.', 'status': 400, **resp}
  96 
  97     attendee = Attendee(user=user, event=event.attendance_event)
  98     attendee.save()
  99 
  100     resp = _get_event_context(event, resp)
  101     return {'message': f'{user} ble meldt på {event}', 'status': 200, **resp}
  102 
  103 
  104 def handle_remove_attendee(event: Event, attendee_id: int, admin_user: User):
  105     resp = _get_event_context(event)
  106     attendee = Attendee.objects.filter(pk=attendee_id)
  107     if attendee.count() != 1:
  108         return {'message': f'Fant ingen påmeldte med oppgitt ID ({attendee_id}).', 'status': 400, **resp}
  109     attendee = attendee[0]
  110     attendee.unattend(admin_user)
  111 
  112     resp = _get_event_context(event, resp)
  113     return {'message': f'{attendee.user} ble fjernet fra {attendee.event}', 'status': 200, **resp}
  114
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/apps/events/dashboard/utils.py b/apps/events/dashboard/utils.py
  --- a/apps/events/dashboard/utils.py
  +++ b/apps/events/dashboard/utils.py
  @@ -65,7 +65,9 @@
               'id': a.id,
               'first_name': a.user.first_name,
               'last_name': a.user.last_name,
  +            'year_of_study': a.user.year,
               'paid': a.paid,
  +            'payment_deadline': a.get_payment_deadline(),
               'extras': str(a.extras),
               'attended': a.attended,
               'link': reverse('dashboard_attendee_details', kwargs={'attendee_id': a.id})
  @@ -77,6 +79,8 @@
   def _get_event_context(event: Event, response={}):
       response['attendees'] = _get_attendee_data(event.attendance_event.attending_attendees_qs)
       response['waitlist'] = _get_attendee_data(event.attendance_event.waitlist_qs)
  +    response['is_payment_event'] = bool(event.attendance_event.payment())
  +    response['has_extras'] = event.attendance_event.has_extras
   
       return response
  
verification_info: {"golden_diff": "diff --git a/apps/events/dashboard/utils.py b/apps/events/dashboard/utils.py\n--- a/apps/events/dashboard/utils.py\n+++ b/apps/events/dashboard/utils.py\n@@ -65,7 +65,9 @@\n             'id': a.id,\n             'first_name': a.user.first_name,\n             'last_name': a.user.last_name,\n+            'year_of_study': a.user.year,\n             'paid': a.paid,\n+            'payment_deadline': a.get_payment_deadline(),\n             'extras': str(a.extras),\n             'attended': a.attended,\n             'link': reverse('dashboard_attendee_details', kwargs={'attendee_id': a.id})\n@@ -77,6 +79,8 @@\n def _get_event_context(event: Event, response={}):\n     response['attendees'] = _get_attendee_data(event.attendance_event.attending_attendees_qs)\n     response['waitlist'] = _get_attendee_data(event.attendance_event.waitlist_qs)\n+    response['is_payment_event'] = bool(event.attendance_event.payment())\n+    response['has_extras'] = event.attendance_event.has_extras\n \n     return response\n", "issue": "Atendee list bug when adding or removing users\n<!-- If this is a security issue or information leakage (having access to something you (probably) shouldn't), please send an email rather than opening a public issue. -->\r\n\r\n## What kind of an issue is this?\r\n\r\n- Bug report\r\n\r\n\r\n## What is the expected behaviour?\r\nIt should look normal where every box and number is under its corresponding column. It should just look normal. Even if we remove users or add users through the dashboard, nothing should change.\r\n\r\n![screenshot from 2018-09-25 21-07-06](https://user-images.githubusercontent.com/41551253/46037365-3b160c80-c108-11e8-9de5-91ef62505aeb.png)\r\n\r\n\r\n## What is the current behaviour?\r\nIf you remove or add a user through the dashboard menu at the attendee list it will look like the screenshot above. We have randomly two boxes, the x for removing users is all the way to the right and the text \"none\" is occupying the remove column. If you refresh the site it will go back to expected behaviour, its only after deleteing/adding a user\r\n\r\n![screenshot from 2018-09-25 20-00-23](https://user-images.githubusercontent.com/41551253/46037343-29346980-c108-11e8-99e1-c69b77695d3e.png)\r\n<!-- if this is a bug report -->\r\n\r\n\r\n## How do you reproduce this problem? \r\nRemove or add a user to the attendee list manually.\r\n<!-- if this is a bug report -->\r\n<!-- provide steps to reproduce this problem, preferably in a bullet point list -->\r\n1. go to the attendee list\r\n2. Add a user by writing their name OR remove a user from the list\r\n## Other information\r\n\r\nThis might be a bug which I didn't catch when I added \"year of study\" to the attendee list. I'm not sure if this was an issue before, but since it hasn't been brought up I will assume this is a bug from that pull request of mine\n", "before_files": [{"content": "# -*- coding: utf-8 -*-\nfrom django.urls import reverse\n\nfrom apps.authentication.models import OnlineUser as User\nfrom apps.events.models import Attendee, Event\n\n\ndef _get_attendee(attendee_id):\n    try:\n        return Attendee.objects.get(pk=attendee_id)\n    except Attendee.DoesNotExist:\n        return None\n\n\ndef event_ajax_handler(event: Event, request):\n    action = request.POST.get('action')\n    administrating_user = request.user\n    attendee_id = request.POST.get('attendee_id')\n    user_id = request.POST.get('user_id')\n\n    if action == 'attended':\n        attendee = _get_attendee(attendee_id)\n        if not attendee:\n            return {'message': f'Fant ingen p\u00e5meldte med oppgitt ID ({attendee_id}).', 'status': 400}\n        return handle_attended(attendee)\n    elif action == 'paid':\n        attendee = _get_attendee(attendee_id)\n        if not attendee:\n            return {'message': f'Fant ingen p\u00e5meldte med oppgitt ID ({attendee_id}).', 'status': 400}\n        return handle_paid(attendee)\n    elif action == 'add_attendee':\n        return handle_add_attendee(event, user_id)\n    elif action == 'remove_attendee':\n        return handle_remove_attendee(event, attendee_id, administrating_user)\n    else:\n        raise NotImplementedError\n\n\ndef handle_attended(attendee: Attendee):\n    \"\"\"\n    Toggle attending-status of an attendee between attending and not attending\n    \"\"\"\n    attendee.attended = not attendee.attended\n    attendee.save()\n\n    return {'message': 'OK', 'status': 200}\n\n\ndef handle_paid(attendee: Attendee):\n    \"\"\"\n    Toggle paid status of an attendee between paid and not paid\n    \"\"\"\n    attendee.paid = not attendee.paid\n    attendee.save()\n\n    return {'message': 'OK', 'status': 200}\n\n\ndef _get_attendee_data(attendee_qs):\n    attendees = []\n\n    for number, a in enumerate(attendee_qs):\n        attendees.append({\n            'number': number + 1,\n            'id': a.id,\n            'first_name': a.user.first_name,\n            'last_name': a.user.last_name,\n            'paid': a.paid,\n            'extras': str(a.extras),\n            'attended': a.attended,\n            'link': reverse('dashboard_attendee_details', kwargs={'attendee_id': a.id})\n        })\n\n    return attendees\n\n\ndef _get_event_context(event: Event, response={}):\n    response['attendees'] = _get_attendee_data(event.attendance_event.attending_attendees_qs)\n    response['waitlist'] = _get_attendee_data(event.attendance_event.waitlist_qs)\n\n    return response\n\n\ndef handle_add_attendee(event: Event, user_id: int):\n    resp = _get_event_context(event)\n    if event.attendance_event.number_of_seats_taken >= event.attendance_event.max_capacity:\n        if not event.attendance_event.waitlist:\n            return {'message': f'Det er ingen ledige plasser p\u00e5 {event.title}.', 'status': 400, **resp}\n\n    user = User.objects.filter(pk=user_id)\n    if user.count() != 1:\n        return {'message': f'Fant ingen bruker med oppgitt ID ({user_id}).', 'status': 400, **resp}\n    user = user[0]\n    if Attendee.objects.filter(user=user, event=event.attendance_event).count() != 0:\n        return {'message': f'{user} er allerede p\u00e5meldt {event.title}.', 'status': 400, **resp}\n\n    attendee = Attendee(user=user, event=event.attendance_event)\n    attendee.save()\n\n    resp = _get_event_context(event, resp)\n    return {'message': f'{user} ble meldt p\u00e5 {event}', 'status': 200, **resp}\n\n\ndef handle_remove_attendee(event: Event, attendee_id: int, admin_user: User):\n    resp = _get_event_context(event)\n    attendee = Attendee.objects.filter(pk=attendee_id)\n    if attendee.count() != 1:\n        return {'message': f'Fant ingen p\u00e5meldte med oppgitt ID ({attendee_id}).', 'status': 400, **resp}\n    attendee = attendee[0]\n    attendee.unattend(admin_user)\n\n    resp = _get_event_context(event, resp)\n    return {'message': f'{attendee.user} ble fjernet fra {attendee.event}', 'status': 200, **resp}\n", "path": "apps/events/dashboard/utils.py"}], "after_files": [{"content": "# -*- coding: utf-8 -*-\nfrom django.urls import reverse\n\nfrom apps.authentication.models import OnlineUser as User\nfrom apps.events.models import Attendee, Event\n\n\ndef _get_attendee(attendee_id):\n    try:\n        return Attendee.objects.get(pk=attendee_id)\n    except Attendee.DoesNotExist:\n        return None\n\n\ndef event_ajax_handler(event: Event, request):\n    action = request.POST.get('action')\n    administrating_user = request.user\n    attendee_id = request.POST.get('attendee_id')\n    user_id = request.POST.get('user_id')\n\n    if action == 'attended':\n        attendee = _get_attendee(attendee_id)\n        if not attendee:\n            return {'message': f'Fant ingen p\u00e5meldte med oppgitt ID ({attendee_id}).', 'status': 400}\n        return handle_attended(attendee)\n    elif action == 'paid':\n        attendee = _get_attendee(attendee_id)\n        if not attendee:\n            return {'message': f'Fant ingen p\u00e5meldte med oppgitt ID ({attendee_id}).', 'status': 400}\n        return handle_paid(attendee)\n    elif action == 'add_attendee':\n        return handle_add_attendee(event, user_id)\n    elif action == 'remove_attendee':\n        return handle_remove_attendee(event, attendee_id, administrating_user)\n    else:\n        raise NotImplementedError\n\n\ndef handle_attended(attendee: Attendee):\n    \"\"\"\n    Toggle attending-status of an attendee between attending and not attending\n    \"\"\"\n    attendee.attended = not attendee.attended\n    attendee.save()\n\n    return {'message': 'OK', 'status': 200}\n\n\ndef handle_paid(attendee: Attendee):\n    \"\"\"\n    Toggle paid status of an attendee between paid and not paid\n    \"\"\"\n    attendee.paid = not attendee.paid\n    attendee.save()\n\n    return {'message': 'OK', 'status': 200}\n\n\ndef _get_attendee_data(attendee_qs):\n    attendees = []\n\n    for number, a in enumerate(attendee_qs):\n        attendees.append({\n            'number': number + 1,\n            'id': a.id,\n            'first_name': a.user.first_name,\n            'last_name': a.user.last_name,\n            'year_of_study': a.user.year,\n            'paid': a.paid,\n            'payment_deadline': a.get_payment_deadline(),\n            'extras': str(a.extras),\n            'attended': a.attended,\n            'link': reverse('dashboard_attendee_details', kwargs={'attendee_id': a.id})\n        })\n\n    return attendees\n\n\ndef _get_event_context(event: Event, response={}):\n    response['attendees'] = _get_attendee_data(event.attendance_event.attending_attendees_qs)\n    response['waitlist'] = _get_attendee_data(event.attendance_event.waitlist_qs)\n    response['is_payment_event'] = bool(event.attendance_event.payment())\n    response['has_extras'] = event.attendance_event.has_extras\n\n    return response\n\n\ndef handle_add_attendee(event: Event, user_id: int):\n    resp = _get_event_context(event)\n    if event.attendance_event.number_of_seats_taken >= event.attendance_event.max_capacity:\n        if not event.attendance_event.waitlist:\n            return {'message': f'Det er ingen ledige plasser p\u00e5 {event.title}.', 'status': 400, **resp}\n\n    user = User.objects.filter(pk=user_id)\n    if user.count() != 1:\n        return {'message': f'Fant ingen bruker med oppgitt ID ({user_id}).', 'status': 400, **resp}\n    user = user[0]\n    if Attendee.objects.filter(user=user, event=event.attendance_event).count() != 0:\n        return {'message': f'{user} er allerede p\u00e5meldt {event.title}.', 'status': 400, **resp}\n\n    attendee = Attendee(user=user, event=event.attendance_event)\n    attendee.save()\n\n    resp = _get_event_context(event, resp)\n    return {'message': f'{user} ble meldt p\u00e5 {event}', 'status': 200, **resp}\n\n\ndef handle_remove_attendee(event: Event, attendee_id: int, admin_user: User):\n    resp = _get_event_context(event)\n    attendee = Attendee.objects.filter(pk=attendee_id)\n    if attendee.count() != 1:\n        return {'message': f'Fant ingen p\u00e5meldte med oppgitt ID ({attendee_id}).', 'status': 400, **resp}\n    attendee = attendee[0]\n    attendee.unattend(admin_user)\n\n    resp = _get_event_context(event, resp)\n    return {'message': f'{attendee.user} ble fjernet fra {attendee.event}', 'status': 200, **resp}\n", "path": "apps/events/dashboard/utils.py"}]}