AKPreference/models.py

+from django.db import models
+from django.utils.translation import gettext_lazy as _
+
+from AKModel.models import AK, AKRequirement, Event
+
+
+class EventParticipant(models.Model):
+    """ A participant describes a person taking part in an event."""
+
+    class Meta:
+        verbose_name = _('Participant')
+        verbose_name_plural = _('Participants')
+        ordering = ['name']
+
+    name = models.CharField(max_length=64, blank=True, verbose_name=_('Nickname'),
+                            help_text=_('Name to identify a participant by (in case of questions from the organizers)'))
+    institution = models.CharField(max_length=128, blank=True, verbose_name=_('Institution'), help_text=_('Uni etc.'))
+
+    event = models.ForeignKey(to=Event, on_delete=models.CASCADE, verbose_name=_('Event'),
+                              help_text=_('Associated event'))
+
+    requirements = models.ManyToManyField(to=AKRequirement, blank=True, verbose_name=_('Requirements'),
+                                          help_text=_("Participant's Requirements"))
+
+    def __str__(self) -> str:
+        string = _("Anonymous {pk}").format(pk=self.pk) if not self.name else self.name
+        if self.institution:
+            string += f" ({self.institution})"
+        return string
+
+    @property
+    def availabilities(self):
+        """
+        Get all availabilities associated to this EventParticipant
+        :return: availabilities
+        :rtype: QuerySet[Availability]
+        """
+        return "Availability".objects.filter(participant=self)
+
+    def get_time_constraints(self) -> list[str]:
+        """Construct list of required time constraint labels."""
+        # local import to prevent cyclic import
+        # pylint: disable=import-outside-toplevel
+        from AKModel.availability.models import Availability
+
+        avails = self.availabilities.all()
+        participant_required_prefs = AKPreference.objects.filter(
+            event=self.event,
+            participant=self,
+            preference=AKPreference.PreferenceLevel.REQUIRED,
+        )
+
+        if (
+            avails
+            and not Availability.is_event_covered(self.event, avails)
+            and participant_required_prefs.exists()
+        ):
+            # participant has restricted availability and is actually required for AKs
+            return [f"availability-participant-{self.pk}"]
+
+        return []
+
+    def get_room_constraints(self) -> list[str]:
+        """Construct list of required room constraint labels."""
+        return list(self.requirements.values_list("name", flat=True).order_by())
+
+    @property
+    def export_preferences(self):
+        """Preferences of this participant with positive score."""
+        return (
+            AKPreference.objects
+            .filter(
+                participant=self, preference__gt=0
+            )
+            .order_by()
+            .select_related('ak')
+            .prefetch_related('ak__akslot_set')
+        )
+
+
+class AKPreference(models.Model):
+    """Model representing the preference of a participant to an AK."""
+
+    class Meta:
+        verbose_name = _('AK Preference')
+        verbose_name_plural = _('AK Preferences')
+        unique_together = [['event', 'participant', 'ak']]
+        ordering = ["-timestamp"]
+
+    event = models.ForeignKey(to=Event, on_delete=models.CASCADE, verbose_name=_('Event'),
+                              help_text=_('Associated event'))
+
+    participant = models.ForeignKey(to=EventParticipant, on_delete=models.CASCADE, verbose_name=_('Participant'),
+                              help_text=_('Participant this preference belongs to'))
+
+    ak = models.ForeignKey(to=AK, on_delete=models.CASCADE, verbose_name=_('AK'),
+                           help_text=_('AK this preference belongs to'))
+
+    class PreferenceLevel(models.IntegerChoices):
+        """
+        Possible preference values
+        """
+        IGNORE = 0, _('Ignore')
+        PREFER = 1, _('Interested')
+        STRONG_PREFER = 2, _("Great interest")
+        REQUIRED = 3, _("Required")
+
+    preference = models.PositiveSmallIntegerField(verbose_name=_('Preference'), choices=PreferenceLevel.choices,
+                                             help_text=_('Preference level for the AK'),
+                                             blank=False,
+                                             default=PreferenceLevel.IGNORE)
+
+    timestamp = models.DateTimeField(auto_now_add=True, verbose_name=_('Timestamp'), help_text=_('Time of creation'))
+
+    def __str__(self) -> str:
+        return f"Preference {self.get_preference_display()} [of '{self.participant}' for AK '{self.ak}']"
+
+    @property
+    def required(self) -> bool:
+        """Whether this preference is a 'REQUIRED'"""
+        return self.preference == self.PreferenceLevel.REQUIRED
+
+    @property
+    def preference_score(self) -> int:
+        """Score of this preference for the solver"""
+        return self.preference if self.preference != self.PreferenceLevel.REQUIRED else -1

AKPreference/serializers.py

+from rest_framework import serializers
+
+from AKModel.models import AKSlot
+from AKModel.serializers import StringListField
+from AKPreference.models import AKPreference, EventParticipant
+
+class ExportAKPreferenceSerializer(serializers.ModelSerializer):
+    """Export serializer for AKPreference objects.
+
+    Used to serialize AKPreference objects for the export to a solver.
+    Part of the implementation of the format of the KoMa solver:
+    https://github.com/Die-KoMa/ak-plan-optimierung/wiki/Input-&-output-format#input--output-format
+    """
+
+    class Meta:
+        model = AKPreference
+        fields = ["required", "preference_score"]
+        read_only_fields = ["required", "preference_score"]
+
+
+class ExportAKPreferencePerSlotSerializer(serializers.BaseSerializer):
+    """Export serializer to associate AKPreferences with the AK's AKSlot objects.
+
+    The AKPreference model stores the preference per AK object.
+    The solver however needs the serialization to be *per AKSlot*, i.e.
+    we need to 'repeat' all preferences for each slot of an AK.
+
+    Part of the implementation of the format of the KoMa solver:
+    https://github.com/Die-KoMa/ak-plan-optimierung/wiki/Input-&-output-format#input--output-format
+    """
+
+    def create(self, validated_data):
+        raise ValueError("`ExportAKPreferencePerSlotSerializer` is read-only.")
+
+    def to_internal_value(self, data):
+        raise ValueError("`ExportAKPreferencePerSlotSerializer` is read-only.")
+
+    def update(self, instance, validated_data):
+        raise ValueError("`ExportAKPreferencePerSlotSerializer` is read-only.")
+
+    def to_representation(self, instance):
+        preference_queryset = instance
+
+        def _insert_akslot_id(serialization_dict: dict, slot: AKSlot) -> dict:
+            """Insert id of the slot into the dict and return it."""
+
+            # The naming scheme of the solver is confusing.
+            # Our 'AKSlot' corresponds to the 'AK' of the solver,
+            # so `ak_id` is the id of the corresponding AKSlot.
+            serialization_dict["ak_id"] = slot.pk
+            return serialization_dict
+
+        return_lst = []
+        for pref in preference_queryset:
+            pref_serialization = ExportAKPreferenceSerializer(pref).data
+            return_lst.extend([
+                _insert_akslot_id(pref_serialization, slot)
+                for slot in pref.ak.akslot_set.all()
+            ])
+        return return_lst
+
+
+class ExportParticipantInfoSerializer(serializers.ModelSerializer):
+    """Serializer of EventParticipant objects for the 'info' field.
+
+    Used in `ExportParticipantSerializer` to serialize EventParticipant objects
+    for the export to a solver. Part of the implementation of the
+    format of the KoMa solver:
+    https://github.com/Die-KoMa/ak-plan-optimierung/wiki/Input-&-output-format#input--output-format
+    """
+    name = serializers.CharField(source="__str__")
+
+    class Meta:
+        model = EventParticipant
+        fields = ["name"]
+        read_only_fields = ["name"]
+
+
+class ExportParticipantSerializer(serializers.ModelSerializer):
+    """Export serializer for EventParticipant objects.
+
+    Used to serialize EventParticipant objects for the export to a solver.
+    Part of the implementation of the format of the KoMa solver:
+    https://github.com/Die-KoMa/ak-plan-optimierung/wiki/Input-&-output-format#input--output-format
+    """
+
+    room_constraints = StringListField(source="get_room_constraints")
+    time_constraints = StringListField(source="get_time_constraints")
+    preferences = ExportAKPreferencePerSlotSerializer(source="export_preferences")
+    info = ExportParticipantInfoSerializer(source="*")
+
+    class Meta:
+        model = EventParticipant
+        fields = ["id", "info", "room_constraints", "time_constraints", "preferences"]
+        read_only_fields = ["id", "info", "room_constraints", "time_constraints", "preferences"]

AKPreference/templates/AKPreference/poll.html

+{% extends 'AKPreference/poll_base.html' %}
+
+{% load i18n %}
+{% load django_bootstrap5 %}
+{% load fontawesome_6 %}
+{% load static %}
+{% load tz %}
+{% load static %}
+
+
+{% block title %}{% trans "AKs" %}: {{ event.name }} - {% trans "Preferences" %}{% endblock %}
+
+{% block imports %}
+    {% include "AKModel/load_fullcalendar_availabilities.html" %}
+
+    <link rel="stylesheet" type='text/css' href="{% static 'common/css/poll.css' %}">
+
+    <script>
+        {% get_current_language as LANGUAGE_CODE %}
+
+        document.addEventListener('DOMContentLoaded', function () {
+            createAvailabilityEditors(
+                '{{ event.timezone }}',
+                '{{ LANGUAGE_CODE }}',
+                '{{ event.start | timezone:event.timezone | date:"Y-m-d H:i:s" }}',
+                '{{ event.end | timezone:event.timezone | date:"Y-m-d H:i:s" }}'
+            );
+        });
+    </script>
+{% endblock %}
+
+{% block breadcrumbs %}
+    {% include "AKPreference/poll_breadcrumbs.html" %}
+    <li class="breadcrumb-item active">{% trans "AK Preference Poll" %}</li>
+{% endblock %}
+
+{% block content %}
+    {% include "messages.html" %}
+
+    {% block headline %}
+        <h2>{% trans 'AK Preference Poll' %}</h2>
+    {% endblock %}
+    <form method="POST" class="post-form">{% csrf_token %}
+        {% block form_contents %}
+            {% bootstrap_form participant_form %}
+            <section>
+                <h3>{% trans "Your AK preferences" %}</h3>
+
+                <p>{% trans "Please enter your preferences." %}</p>
+
+                {{ formset.management_form }}
+
+                <div class="container radio-flex">
+                    {% for category, forms in grouped_forms %}
+                        <details open>
+                            <summary
+                                    class="ak-category-header">{{ category.name }}</summary>
+                            <div class="row row-cols-1 row-cols-lg-2">
+                                {% for innerform in forms %}
+                                    {% bootstrap_form_errors innerform type='non_fields' %}
+                                    {% for field in innerform.hidden_fields %}
+                                        {{ field }}
+                                    {% endfor %}
+                                    <div class="container radio-group col">
+                                        <div class="container radio-info">
+                                            <details>
+                                                <summary class="ak-header">{{ innerform.preference.label }}
+                                                    {% if innerform.ak_obj.reso %}
+                                                        <span class="badge bg-dark rounded-pill"
+                                                              title="{% trans 'Intends to submit a resolution' %}">{% fa6_icon "scroll" 'fas' %}</span>
+                                                    {% endif %}
+                                                </summary>
+                                                <p>{{ innerform.ak_obj.description }}</p>
+                                                {% if innerform.ak_obj.owners_list %}
+                                                    <p>{% trans "Responsible" %}: {{ innerform.ak_obj.owners_list }}</p>
+                                                {% endif %}
+                                                {% if show_types %}
+                                                    <p>
+                                                    {% for aktype in innerform.ak_obj.types.all %}
+                                                        <span class="badge bg-light">{{ aktype.name }}</span>&nbsp;
+                                                    {% endfor %}
+                                                    </p>
+                                                {% endif %}
+                                                {% if innerform.ak_obj.reso %}
+                                                    <!-- TODO: reso as an icon -->
+                                                    <p><i>{% trans "Intends to submit a resolution" %}.</i></p>
+                                                {% endif %}
+                                            </details>
+                                        </div>
+                                        {% bootstrap_field innerform.preference show_label=False show_help=False field_class="pref-cls" %}
+                                    </div>
+                                {% endfor %}
+                            </div>
+                        </details>
+                    {% endfor %}
+                </div>
+            </section>
+        {% endblock %}
+
+        <h2 class="text-warning mb-4 text-end">{% trans "Careful: after saving your preferences, you cannot edit them again!" %}</h2>
+
+        <button type="submit" class="save btn btn-primary float-end">
+            {% fa6_icon "check" 'fas' %} {% trans "Submit" %}
+        </button>
+
+        <button type="reset" class="btn btn-danger">
+            {% fa6_icon "undo-alt" 'fas' %} {% trans "Reset Form" %}
+        </button>
+
+        <a href="{% url 'dashboard:dashboard_event' slug=event.slug %}" class="btn btn-secondary">
+            {% fa6_icon "times" 'fas' %} {% trans "Cancel" %}
+        </a>
+    </form>
+{% endblock %}
+
+{% block bottom_script %}
+    <script src="{% static 'common/vendor/chosen-js/chosen.jquery.js' %}"></script>
+    <script>
+        $(function () {
+            $('.chosen-select').chosen();
+        });
+    </script>
+{% endblock %}

AKPreference/templates/AKPreference/poll_base.html

+{% extends "base.html" %}
+
+{% load fontawesome_6 %}
+{% load i18n %}
+
+{% block breadcrumbs %}
+    {% include "AKPreference/poll_breadcrumbs.html" %}
+{% endblock %}
+
+{% block footer_custom %}
+    {% if event.contact_email %}
+        <h4>
+            <a href="mailto:{{ event.contact_email }}">{% fa6_icon "envelope" 'fas' %} {% trans "Write to organizers of this event for questions and comments" %}</a>
+        </h4>
+    {% endif %}
+{% endblock %}

AKPreference/templates/AKPreference/poll_breadcrumbs.html

+{% load tags_AKModel %}
+
+<li class="breadcrumb-item">
+    {% if 'AKDashboard'|check_app_installed %}
+        <a href="{% url 'dashboard:dashboard' %}">AKPlanning</a>
+    {% else %}
+        AKPlanning
+    {% endif %}
+</li>
+<li class="breadcrumb-item">
+    {% if 'AKDashboard'|check_app_installed %}
+        <a href="{% url 'dashboard:dashboard_event' slug=event.slug %}">{{ event }}</a>
+    {% else %}
+        {{ event }}
+    {% endif %}
+</li>

AKPreference/templates/AKPreference/poll_not_configured.html

+{% extends 'AKPreference/poll_base.html' %}
+
+{% load i18n %}
+{% load fontawesome_6 %}
+{% load static %}
+
+{% block title %}{% trans "AKs" %}: {{ event.name }} - {% trans "AK Preference Poll" %}{% endblock %}
+
+{% block breadcrumbs %}
+    {% include "AKPreference/poll_breadcrumbs.html" %}
+    <li class="breadcrumb-item active">{% trans "AK Preference Poll" %}</li>
+{% endblock %}
+
+{% block content %}
+    <h1>{{ event.name }}</h1>
+
+    {% include "messages.html" %}
+
+    <div class="alert alert-warning" style="margin-top:20px;margin-bottom: 20px;">
+            {% trans "System is not yet configured for AK preference polling. Please try again later." %}
+        </div>
+{% endblock %}

AKPreference/tests.py

+from django.urls import reverse
+from django.test import TestCase
+
+from AKModel.models import Event
+from AKModel.tests.test_views import BasicViewTests
+
+class PollViewTests(BasicViewTests, TestCase):
+    """
+    Tests for AKPreference Poll
+    """
+    fixtures = ['model.json']
+    APP_NAME = 'poll'
+
+    def test_poll_redirect(self):
+        """
+        Test: Make sure that user is redirected from poll to dashboard when poll is hidden
+        """
+        event = Event.objects.get(slug='kif42')
+        _, url_poll = self._name_and_url(('poll', {'event_slug': event.slug}))
+        url_dashboard = reverse("dashboard:dashboard_event", kwargs={"slug": event.slug})
+
+        event.poll_hidden = True
+        event.save()
+
+        self.client.logout()
+        response = self.client.get(url_poll)
+
+        self.assertRedirects(response, url_dashboard,
+                             msg_prefix=f"Redirect away from poll not working ({url_poll} -> {url_dashboard})")
+
+        self.client.force_login(self.staff_user)
+        response = self.client.get(url_poll)
+
+        self.assertEqual(
+            response.status_code,
+            200,
+            msg=f"{url_poll} broken",
+        )
+
+        self.assertTemplateUsed(response, "AKPreference/poll.html", msg_prefix="Poll is not visible for staff user")

AKPreference/urls.py

+from django.urls import include, path
+
+from . import views
+
+app_name = "poll"
+
+urlpatterns = [
+    path(
+        "<slug:event_slug>/poll/",
+        include(
+            [
+                path("", views.PreferencePollCreateView.as_view(), name="poll"),
+            ]
+        ),
+    ),
+]

AKPreference/views.py

+import json
+from itertools import groupby
+
+from django import forms
+from django.contrib import messages
+from django.contrib.messages.views import SuccessMessageMixin
+from django.shortcuts import redirect
+from django.urls import reverse_lazy
+from django.utils.translation import gettext_lazy as _
+from django.views.generic import FormView
+
+from AKModel.availability.models import Availability
+from AKModel.availability.serializers import AvailabilityFormSerializer
+from AKModel.metaviews.admin import EventSlugMixin
+from AKModel.models import AK
+from AKPreference.models import AKPreference
+from .forms import EventParticipantForm
+
+
+class PreferencePollCreateView(EventSlugMixin, SuccessMessageMixin, FormView):
+    """
+    View: Show a form to register the AK preference of a participant.
+
+    The form creates the `EventParticipant` instance as well as the
+    AKPreferences for each AK of the event.
+
+    For the creation of the event participant, a `EventParticipantForm` is used.
+    For the preferences, a ModelFormset is created.
+    """
+
+    form_class = forms.Form
+    model = AKPreference
+    form_class = forms.modelform_factory(
+            model=AKPreference, fields=["preference", "ak", "event"]
+    )
+    template_name = "AKPreference/poll.html"
+    success_message = _("AK preferences were registered successfully")
+
+    def _create_modelformset(self):
+        return forms.modelformset_factory(
+                model=AKPreference,
+                fields=["preference", "ak", "event"],
+                widgets={
+                    "ak": forms.HiddenInput,
+                    "event": forms.HiddenInput,
+                    "preference": forms.RadioSelect,
+                },
+                extra=0,
+        )
+
+    def get(self, request, *args, **kwargs):
+        s = super().get(request, *args, **kwargs)
+        # Don't show preference form when event is not active or poll is hidden -> redirect to dashboard
+        if not self.event.active or (self.event.poll_hidden and not request.user.is_staff):
+            return redirect(self.get_success_url())
+        return s
+
+    def get_success_url(self):
+        return reverse_lazy(
+                "dashboard:dashboard_event", kwargs={"slug": self.event.slug}
+        )
+
+    def get_context_data(self, **kwargs):
+        context = super().get_context_data(**kwargs)
+        ak_set = (
+            AK.objects.filter(event=self.event)
+            .order_by()
+            .all()
+            .prefetch_related('owners')
+        )
+        initial_lst = [
+            {"ak": ak, "event": self.event} for ak in ak_set
+        ]
+
+        context["formset"] = self._create_modelformset()(
+                queryset=AKPreference.objects.none(),
+                initial=initial_lst,
+        )
+        context["formset"].extra = len(initial_lst)
+
+        for form, init in zip(context["formset"], initial_lst, strict=True):
+            form.fields["preference"].label = init["ak"].name
+            form.fields["preference"].help_text = (
+                    "Description: " + init["ak"].description
+            )
+            form.ak_obj = init["ak"]
+
+        sorted_forms = sorted(
+                context["formset"],
+                key=lambda f: (f.ak_obj.category.name, f.ak_obj.id)
+        )
+        grouped_forms = [
+            (category, list(forms))
+            for category, forms in groupby(sorted_forms, key=lambda f: f.ak_obj.category)
+        ]
+        context["grouped_forms"] = grouped_forms
+        availabilities_serialization = AvailabilityFormSerializer(
+                (
+                    [Availability.with_event_length(event=self.event)],
+                    self.event,
+                )
+        )
+
+        context["participant_form"] = EventParticipantForm(
+                initial={
+                    "event": self.event,
+                    "availabilities": json.dumps(availabilities_serialization.data),
+                }
+        )
+        context['show_types'] = self.event.aktype_set.count() > 0
+        return context
+
+    def post(self, request, *args, **kwargs):
+        self._load_event()
+        model_formset_cls = self._create_modelformset()
+        formset = model_formset_cls(request.POST)
+        participant_form = EventParticipantForm(
+                data=request.POST, initial={"event": self.event}
+        )
+        if formset.is_valid() and participant_form.is_valid():
+            return self.form_valid(form=(formset, participant_form))
+        return self.form_invalid(form=(formset, participant_form))
+
+    def form_valid(self, form):
+        try:
+            formset, participant_form = form
+            participant = participant_form.save()
+            instances = formset.save(commit=False)
+            for instance in instances:
+                instance.participant = participant
+                instance.save()
+            success_message = self.get_success_message(participant_form.cleaned_data)
+            if success_message:
+                messages.success(self.request, success_message)
+        except:
+            messages.error(
+                    self.request,
+                    _(
+                            "Something went wrong. Your preferences were not saved. "
+                            "Please try again or contact the organizers."
+                    ),
+            )
+            return self.form_invalid(form=form)
+        return redirect(self.get_success_url())

AKScheduling/admin.py

-# Register your models here.

AKScheduling/api.py

+from django.contrib.auth.mixins import LoginRequiredMixin
+from django.http import JsonResponse
+from django.shortcuts import get_object_or_404
+from django.urls import reverse
+from django.utils import timezone
+from django.views.generic import ListView
+from rest_framework import viewsets, mixins, serializers, permissions
+
+from AKModel.availability.models import Availability
+from AKModel.models import Room, AKSlot, ConstraintViolation, DefaultSlot
+from AKModel.metaviews.admin import EventSlugMixin
+
+
+class ResourceSerializer(serializers.ModelSerializer):
+    """
+    REST Framework Serializer for Rooms to produce format required for fullcalendar resources
+    """
+    class Meta:
+        model = Room
+        fields = ['id', 'title']
+
+    title = serializers.SerializerMethodField('transform_title')
+
+    @staticmethod
+    def transform_title(obj):
+        """
+        Adapt title, add capacity information if room has a restriction (capacity is not -1)
+        """
+        if obj.capacity > 0:
+            return f"{obj.title} [{obj.capacity}]"
+        return obj.title
+
+
+class ResourcesViewSet(EventSlugMixin, mixins.ListModelMixin, viewsets.GenericViewSet):
+    """
+    API View: Rooms (resources to schedule for in fullcalendar)
+
+    Read-only, adaption to fullcalendar format through :class:`ResourceSerializer`
+    """
+    permission_classes = (permissions.DjangoModelPermissions,)
+    serializer_class = ResourceSerializer
+
+    def get_queryset(self):
+        return Room.objects.filter(event=self.event).order_by('location', 'name')
+
+
+class EventsView(LoginRequiredMixin, EventSlugMixin, ListView):
+    """
+    API View: Slots (events to schedule in fullcalendar)
+
+    Read-only, JSON formatted response is created manually since it requires a bunch of "custom" fields that have
+    different names compared to the normal model or are not present at all and need to be computed to create the
+    required format for fullcalendar.
+    """
+    model = AKSlot
+
+    def get_queryset(self):
+        return super().get_queryset().select_related('ak').filter(
+            event=self.event, room__isnull=False, start__isnull=False
+        )
+
+    def render_to_response(self, context, **response_kwargs):
+        return JsonResponse(
+            [{
+                "slotID": slot.pk,
+                "title": f'{slot.ak.short_name}:\n{slot.ak.owners_list}',
+                "description": slot.ak.details,
+                "resourceId": slot.room.id,
+                "start": timezone.localtime(slot.start, self.event.timezone).strftime("%Y-%m-%d %H:%M:%S"),
+                "end": timezone.localtime(slot.end, self.event.timezone).strftime("%Y-%m-%d %H:%M:%S"),
+                "backgroundColor": slot.ak.category.color,
+                "borderColor":
+                    "#2c3e50" if slot.fixed
+                    else '#e74c3c' if slot.constraintviolation_set.count() > 0
+                    else slot.ak.category.color,
+                "constraint": 'roomAvailable',
+                "editable": not slot.fixed,
+                'url': str(reverse('admin:AKModel_akslot_change', args=[slot.pk])),
+            } for slot in context["object_list"]],
+            safe=False,
+            **response_kwargs
+        )
+
+
+class RoomAvailabilitiesView(LoginRequiredMixin, EventSlugMixin, ListView):
+    """
+    API view: Availabilities of rooms
+
+    Read-only, JSON formatted response is created manually since it requires a bunch of "custom" fields that have
+    different names compared to the normal model or are not present at all and need to be computed to create the
+    required format for fullcalendar.
+    """
+    model = Availability
+    context_object_name = "availabilities"
+
+    def get_queryset(self):
+        return super().get_queryset().filter(event=self.event, room__isnull=False)
+
+    def render_to_response(self, context, **response_kwargs):
+        return JsonResponse(
+            [{
+                "title": "",
+                "resourceId": a.room.id,
+                "start": timezone.localtime(a.start, self.event.timezone).strftime("%Y-%m-%d %H:%M:%S"),
+                "end": timezone.localtime(a.end, self.event.timezone).strftime("%Y-%m-%d %H:%M:%S"),
+                "display": 'background',
+                "groupId": 'roomAvailable',
+            } for a in context["availabilities"]],
+            safe=False,
+            **response_kwargs
+        )
+
+
+class DefaultSlotsView(LoginRequiredMixin, EventSlugMixin, ListView):
+    """
+    API view: default slots
+
+    Read-only, JSON formatted response is created manually since it requires a bunch of "custom" fields that have
+    different names compared to the normal model or are not present at all and need to be computed to create the
+    required format for fullcalendar.
+    """
+    model = DefaultSlot
+    context_object_name = "default_slots"
+
+    def get_queryset(self):
+        return super().get_queryset().filter(event=self.event)
+
+    def render_to_response(self, context, **response_kwargs):
+        all_room_ids = [r.pk for r in self.event.room_set.all()]
+        return JsonResponse(
+            [{
+                "title": "",
+                "resourceIds": all_room_ids,
+                "start": timezone.localtime(a.start, self.event.timezone).strftime("%Y-%m-%d %H:%M:%S"),
+                "end": timezone.localtime(a.end, self.event.timezone).strftime("%Y-%m-%d %H:%M:%S"),
+                "display": 'background',
+                "groupId": 'defaultSlot',
+                "backgroundColor": '#69b6d4'
+            } for a in context["default_slots"]],
+            safe=False,
+            **response_kwargs
+        )
+
+
+class EventSerializer(serializers.ModelSerializer):
+    """
+    REST framework serializer to adapt between AKSlot model and the event format of fullcalendar
+    """
+    class Meta:
+        model = AKSlot
+        fields = ['id', 'start', 'end', 'roomId']
+
+    start = serializers.DateTimeField()
+    end = serializers.DateTimeField()
+    roomId = serializers.IntegerField(source='room.pk')
+
+    def update(self, instance, validated_data):
+        # Ignore timezone of input (treat it as timezone-less) and set the event timezone
+        # By working like this, the client does not need to know about timezones, since every timestamp it deals with
+        # has the timezone offsets already applied
+        start = timezone.make_aware(timezone.make_naive(validated_data.get('start')), instance.event.timezone)
+        end = timezone.make_aware(timezone.make_naive(validated_data.get('end')), instance.event.timezone)
+        instance.start = start
+        # Also, adapt from start & end format of fullcalendar to our start & duration model
+        diff = end - start
+        instance.duration = round(diff.days * 24 + (diff.seconds / 3600), 2)
+
+        # Updated room if needed (pk changed -- otherwise, no need for an additional database lookup)
+        new_room_id = validated_data.get('room')["pk"]
+        if instance.room is None or instance.room.pk != new_room_id:
+            instance.room = get_object_or_404(Room, pk=new_room_id)
+
+        instance.save()
+        return instance
+
+
+class EventsViewSet(EventSlugMixin, mixins.UpdateModelMixin, viewsets.GenericViewSet):
+    """
+    API view: Update scheduling of a slot (event in fullcalendar format)
+
+    Write-only (will however reply with written values to PUT request)
+    """
+    permission_classes = (permissions.DjangoModelPermissions,)
+    serializer_class = EventSerializer
+
+    def get_object(self):
+        return get_object_or_404(AKSlot, pk=self.kwargs["pk"])
+
+    def get_queryset(self):
+        return AKSlot.objects.filter(event=self.event)
+
+
+class ConstraintViolationSerializer(serializers.ModelSerializer):
+    """
+    REST Framework Serializer for constraint violations
+    """
+    class Meta:
+        model = ConstraintViolation
+        fields = ['pk', 'type_display', 'aks', 'ak_slots', 'ak_owner', 'room', 'requirement', 'category', 'comment',
+                  'timestamp_display', 'manually_resolved', 'level_display', 'details', 'edit_url']
+
+
+class ConstraintViolationsViewSet(EventSlugMixin, mixins.ListModelMixin, viewsets.GenericViewSet):
+    """
+    API View: Constraint Violations of an event
+
+    Read-only, fields and model selected in :class:`ConstraintViolationSerializer`
+    """
+    permission_classes = (permissions.DjangoModelPermissions,)
+    serializer_class = ConstraintViolationSerializer
+
+    def get_queryset(self):
+        # Optimize query to reduce database load
+        return (ConstraintViolation.objects.select_related('event', 'room')
+                .prefetch_related('aks', 'ak_slots', 'ak_owner', 'requirement', 'category')
+                .filter(event=self.event).order_by('manually_resolved', '-type', '-timestamp'))

AKScheduling/apps.py

@@ -2,4 +2,7 @@ from django.apps import AppConfig
 
 
 class AkschedulingConfig(AppConfig):
+    """
+    App configuration (default, only specifies name of the app)
+    """
     name = 'AKScheduling'

AKScheduling/forms.py

+from django import forms
+from django.utils.translation import gettext_lazy as _
+
+from AKModel.models import AK
+
+
+class AKInterestForm(forms.ModelForm):
+    """
+    Form for quickly changing the interest count and notes of an AK
+    """
+    required_css_class = 'required'
+
+    class Meta:
+        model = AK
+        fields = ['interest',
+                  'notes',
+                  ]
+
+
+class AKAddSlotForm(forms.Form):
+    """
+    Form to create a new slot for an existing AK directly from scheduling view
+    """
+    start = forms.CharField(label=_("Start"), disabled=True)
+    end = forms.CharField(label=_("End"), disabled=True)
+    duration = forms.CharField(label=_("Duration"), disabled=True)
+    room = forms.IntegerField(label=_("Room"), disabled=True, widget=forms.HiddenInput())
+    room_name = forms.CharField(label=_("Room"), disabled=True)
+
+    def __init__(self, event):
+        super().__init__()
+        self.fields['ak'] = forms.ModelChoiceField(event.ak_set.all(), label=_("AK"))

AKScheduling/locale/de_DE/LC_MESSAGES/django.po

+# SOME DESCRIPTIVE TITLE.
+# Copyright (C) YEAR THE PACKAGE'S COPYRIGHT HOLDER
+# This file is distributed under the same license as the PACKAGE package.
+# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
+#
+#, fuzzy
+msgid ""
+msgstr ""
+"Project-Id-Version: PACKAGE VERSION\n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: 2025-06-18 12:09+0000\n"
+"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
+"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
+"Language-Team: LANGUAGE <LL@li.org>\n"
+"Language: \n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+
+#: AKScheduling/forms.py:24
+msgid "Start"
+msgstr "Start"
+
+#: AKScheduling/forms.py:25
+msgid "End"
+msgstr "Ende"
+
+#: AKScheduling/forms.py:26
+msgid "Duration"
+msgstr "Dauer"
+
+#: AKScheduling/forms.py:27 AKScheduling/forms.py:28
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:172
+msgid "Room"
+msgstr "Raum"
+
+#: AKScheduling/forms.py:32
+msgid "AK"
+msgstr "AK"
+
+#: AKScheduling/models.py:92
+#, python-format
+msgid ""
+"Not enough space for AK interest (Interest: %(interest)d, Capacity: "
+"%(capacity)d)"
+msgstr ""
+"Nicht genug Platz für AK-Interesse (Interesse: %(interest)d, Kapazität: "
+"%(capacity)d)"
+
+#: AKScheduling/models.py:106
+#, python-format
+msgid ""
+"Space is too close to AK interest (Interest: %(interest)d, Capacity: "
+"%(capacity)d)"
+msgstr ""
+"Verfügbarer Platz zu dicht an Interesse (Interesse: %(interest)d, Kapazität: "
+"%(capacity)d)"
+
+#: AKScheduling/templates/admin/AKScheduling/constraint_violations.html:11
+msgid "Constraint Violations for"
+msgstr ""
+
+#: AKScheduling/templates/admin/AKScheduling/constraint_violations.html:44
+#: AKScheduling/templates/admin/AKScheduling/constraint_violations.html:105
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:241
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:378
+msgid "No violations"
+msgstr "Keine Verletzungen"
+
+#: AKScheduling/templates/admin/AKScheduling/constraint_violations.html:82
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:347
+msgid "Violation(s)"
+msgstr "Verletzung(en)"
+
+#: AKScheduling/templates/admin/AKScheduling/constraint_violations.html:85
+msgid "Auto reload?"
+msgstr "Automatisch neu laden?"
+
+#: AKScheduling/templates/admin/AKScheduling/constraint_violations.html:89
+msgid "Reload now"
+msgstr "Jetzt neu laden"
+
+#: AKScheduling/templates/admin/AKScheduling/constraint_violations.html:95
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:229
+msgid "Violation"
+msgstr "Verletzung"
+
+#: AKScheduling/templates/admin/AKScheduling/constraint_violations.html:96
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:372
+msgid "Problem"
+msgstr "Problem"
+
+#: AKScheduling/templates/admin/AKScheduling/constraint_violations.html:97
+msgid "Details"
+msgstr "Details"
+
+#: AKScheduling/templates/admin/AKScheduling/constraint_violations.html:98
+msgid "Since"
+msgstr "Seit"
+
+#: AKScheduling/templates/admin/AKScheduling/constraint_violations.html:111
+#: AKScheduling/templates/admin/AKScheduling/manage_tracks.html:256
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:333
+#: AKScheduling/templates/admin/AKScheduling/special_attention.html:58
+#: AKScheduling/templates/admin/AKScheduling/unscheduled.html:34
+msgid "Event Status"
+msgstr "Event-Status"
+
+#: AKScheduling/templates/admin/AKScheduling/constraint_violations.html:113
+msgid "Scheduling"
+msgstr "Scheduling"
+
+#: AKScheduling/templates/admin/AKScheduling/interest.html:32
+msgid "Submit"
+msgstr "Abschicken"
+
+#: AKScheduling/templates/admin/AKScheduling/manage_tracks.html:11
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:21
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:330
+msgid "Scheduling for"
+msgstr "Scheduling für"
+
+#: AKScheduling/templates/admin/AKScheduling/manage_tracks.html:135
+msgid "Name of new ak track"
+msgstr "Name des neuen AK-Tracks"
+
+#: AKScheduling/templates/admin/AKScheduling/manage_tracks.html:151
+msgid "Could not create ak track"
+msgstr "Konnte neuen AK-Track nicht anlegen"
+
+#: AKScheduling/templates/admin/AKScheduling/manage_tracks.html:177
+msgid "Could not update ak track name"
+msgstr "Konnte Namen des AK-Tracks nicht ändern"
+
+#: AKScheduling/templates/admin/AKScheduling/manage_tracks.html:183
+msgid "Do you really want to delete this ak track?"
+msgstr "Soll dieser AK-Track wirklich gelöscht werden?"
+
+#: AKScheduling/templates/admin/AKScheduling/manage_tracks.html:197
+msgid "Could not delete ak track"
+msgstr "AK-Track konnte nicht gelöscht werden"
+
+#: AKScheduling/templates/admin/AKScheduling/manage_tracks.html:216
+msgid "Manage AK Tracks"
+msgstr "AK-Tracks verwalten"
+
+#: AKScheduling/templates/admin/AKScheduling/manage_tracks.html:217
+msgid "Add ak track"
+msgstr "AK-Track hinzufügen"
+
+#: AKScheduling/templates/admin/AKScheduling/manage_tracks.html:222
+msgid "AKs without track"
+msgstr "AKs ohne Track"
+
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:106
+msgid "Day (Horizontal)"
+msgstr "Tag (horizontal)"
+
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:113
+msgid "Day (Vertical)"
+msgstr "Tag (vertikal)"
+
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:124
+msgid "Event (Horizontal)"
+msgstr "Event (horizontal)"
+
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:133
+msgid "Event (Vertical)"
+msgstr "Event (vertikal)"
+
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:272
+msgid "Please choose AK"
+msgstr "Bitte AK auswählen"
+
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:292
+msgid "Could not create slot"
+msgstr "Konnte Slot nicht anlegen"
+
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:308
+msgid "Add slot"
+msgstr "Slot hinzufügen"
+
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:316
+msgid "Add"
+msgstr "Hinzufügen"
+
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:317
+msgid "Cancel"
+msgstr "Abbrechen"
+
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:344
+msgid "Unscheduled"
+msgstr "Nicht gescheduled"
+
+#: AKScheduling/templates/admin/AKScheduling/scheduling.html:371
+msgid "Level"
+msgstr "Level"
+
+#: AKScheduling/templates/admin/AKScheduling/special_attention.html:14
+msgid "AKs with public notes"
+msgstr "AKs mit öffentlichen Kommentaren"
+
+#: AKScheduling/templates/admin/AKScheduling/special_attention.html:24
+msgid "AKs without availabilities"
+msgstr "AKs ohne Verfügbarkeiten"
+
+#: AKScheduling/templates/admin/AKScheduling/special_attention.html:33
+msgid "Create default availabilities"
+msgstr "Standardverfügbarkeiten anlegen"
+
+#: AKScheduling/templates/admin/AKScheduling/special_attention.html:36
+msgid "AK wishes with slots"
+msgstr "AK-Wünsche mit Slots"
+
+#: AKScheduling/templates/admin/AKScheduling/special_attention.html:46
+msgid "Delete slots for wishes"
+msgstr ""
+
+#: AKScheduling/templates/admin/AKScheduling/special_attention.html:48
+msgid "AKs without slots"
+msgstr "AKs ohne Slots"
+
+#: AKScheduling/templates/admin/AKScheduling/status/cvs.html:6
+msgid ""
+"\n"
+"            <h3>Constraint Violation</h3>\n"
+"            "
+msgid_plural ""
+"\n"
+"            <h3>Constraint Violations</h3>\n"
+"        "
+msgstr[0] ""
+"\n"
+"            <h3>Constraintverletzung</h3>\n"
+"            "
+msgstr[1] ""
+"\n"
+"            <h3>Constraintverletzungen</h3>\n"
+"        "
+
+#: AKScheduling/templates/admin/AKScheduling/unscheduled.html:7
+msgid "Unscheduled AK Slots"
+msgstr "Noch nicht geschedulte AK-Slots"
+
+#: AKScheduling/templates/admin/AKScheduling/unscheduled.html:11
+msgid "Count"
+msgstr "Anzahl"
+
+#: AKScheduling/views.py:152
+msgid "Interest updated"
+msgstr "Interesse aktualisiert"
+
+#: AKScheduling/views.py:210
+msgid "Wishes"
+msgstr "Wünsche"
+
+#: AKScheduling/views.py:228
+msgid "Cleanup: Delete unscheduled slots for wishes"
+msgstr "Aufräumen: Noch nicht geplante Slots für Wünsche löschen"
+
+#: AKScheduling/views.py:235
+#, python-brace-format
+msgid ""
+"The following {count} unscheduled slots of wishes will be deleted:\n"
+"\n"
+" {slots}"
+msgstr ""
+"Die folgenden {count} noch nicht geplanten Slots von Wünschen werden "
+"gelöscht:\n"
+"\n"
+" {slots}"
+
+#: AKScheduling/views.py:242
+msgid "Unscheduled slots for wishes successfully deleted"
+msgstr "Noch nicht geplante Slots für Wünsche erfolgreich gelöscht"
+
+#: AKScheduling/views.py:256
+msgid "Create default availabilities for AKs"
+msgstr "Standardverfügbarkeiten für AKs anlegen"
+
+#: AKScheduling/views.py:263
+#, python-brace-format
+msgid ""
+"The following {count} AKs don't have any availability information. Create "
+"default availability for them:\n"
+"\n"
+" {aks}"
+msgstr ""
+"Die folgenden {count} AKs haben keine Verfügbarkeitsinformationen. "
+"Standardverfügbarkeiten für sie anlegen:\n"
+"\n"
+" {aks}"
+
+#: AKScheduling/views.py:283
+#, python-brace-format
+msgid "Could not create default availabilities for AK: {ak}"
+msgstr "Konnte keine Verfügbarkeit anlegen für AK: {ak}"
+
+#: AKScheduling/views.py:288
+#, python-brace-format
+msgid "Created default availabilities for {count} AKs"
+msgstr "Standardverfügbarkeiten für {count} AKs angelegt"
+
+#: AKScheduling/views.py:299
+msgid "Constraint Violations"
+msgstr "Constraintverletzungen"
+
+#~ msgid "Constraint violations for"
+#~ msgstr "Constraintverletzungen für"
+
+#~ msgid "AKs requiring special attention for"
+#~ msgstr "AKs die besondere Aufmerksamkeit erfordern für"
+
+#~ msgid "Enter interest"
+#~ msgstr "Interesse eingeben"
+
+#~ msgid "Bitte AK auswählen"
+#~ msgstr "Please sel"
+
+#~ msgid "Cannot load current violations from server"
+#~ msgstr "Kann die aktuellen Verletzungen nicht vom Server laden"

AKScheduling/models.py

-# Create your models here.
+# This file mainly contains signal receivers, which follow a very strong interface, having e.g., a sender attribute
+# that is hardly used by us. Nevertheless, to follow the django receiver coding style and since changes might
+# cause issues when loading fixtures or model dumps, it is not wise to replace that attribute with "_".
+# Therefore, the check that finds unused arguments is disabled for this whole file:
+# pylint: disable=unused-argument
+
+from django.db.models.signals import post_save, m2m_changed, pre_delete
+from django.dispatch import receiver
+from django.utils.translation import gettext_lazy as _
+
+from AKModel.availability.models import Availability
+from AKModel.models import AK, AKSlot, Room, Event, ConstraintViolation
+
+
+def update_constraint_violations(new_violations, existing_violations_to_check):
+    """
+    Update existing constraint violations (subset for which new violations were computed) based on these new violations.
+    This will add all new violations without a match, preserve the matching ones
+    and delete the obsolete ones (those without a match from the newly calculated violations).
+
+    :param new_violations: list of new (not yet saved) violations that exist after the last change
+    :type new_violations: list[ConstraintViolation]
+    :param existing_violations_to_check: list of related violations currently in the db
+    :type existing_violations_to_check: list[ConstraintViolation]
+    """
+    for new_violation in new_violations:
+        found_match = False
+        for existing_violation in existing_violations_to_check:
+            if existing_violation.matches(new_violation):
+                # Remove from existing violations set since it should stay in db
+                existing_violations_to_check.remove(existing_violation)
+                found_match = True
+                break
+
+        # Only save new violation if no match was found
+        if not found_match:
+            new_violation.save()
+
+    # Cleanup obsolete violations (ones without matches computed under current conditions)
+    for outdated_violation in existing_violations_to_check:
+        outdated_violation.delete()
+
+
+def update_cv_reso_deadline_for_slot(slot):
+    """
+    Update constraint violation AK_AFTER_RESODEADLINE for given slot
+
+    :param slot: slot to check/update
+    :type slot: AKSlot
+    """
+    event = slot.event
+
+    # Update only if reso_deadline exists
+    # if event was changed and reso_deadline is removed, CVs will be deleted by event changed handler
+    # Update only has to be done for already scheduled slots with reso intention
+    if slot.ak.reso and slot.event.reso_deadline and slot.start:
+        violation_type = ConstraintViolation.ViolationType.AK_AFTER_RESODEADLINE
+        new_violations = []
+
+        # Violation?
+        if slot.end > event.reso_deadline:
+            c = ConstraintViolation(
+                type=violation_type,
+                level=ConstraintViolation.ViolationLevel.VIOLATION,
+                event=event,
+            )
+            c.aks_tmp.add(slot.ak)
+            c.ak_slots_tmp.add(slot)
+            new_violations.append(c)
+        update_constraint_violations(new_violations, list(slot.constraintviolation_set.filter(type=violation_type)))
+
+
+def check_capacity_for_slot(slot: AKSlot):
+    """
+    Check whether this slot violates the capacity requirement
+
+    :param slot: slot to check
+    :type slot: AKSlot
+    :return: Violation (if any) or None
+    :rtype: ConstraintViolation or None
+    """
+
+    # If slot is scheduled in a room and interest was specified
+    if slot.room and slot.room.capacity >= 0 and slot.ak.interest >= 0:
+        # Create a violation if interest exceeds room capacity
+        if slot.room.capacity < slot.ak.interest:
+            c = ConstraintViolation(
+                type=ConstraintViolation.ViolationType.ROOM_CAPACITY_EXCEEDED,
+                level=ConstraintViolation.ViolationLevel.VIOLATION,
+                event=slot.event,
+                room=slot.room,
+                comment=_("Not enough space for AK interest (Interest: %(interest)d, Capacity: %(capacity)d)")
+                        % {'interest': slot.ak.interest, 'capacity': slot.room.capacity},
+            )
+            c.ak_slots_tmp.add(slot)
+            c.aks_tmp.add(slot.ak)
+            return c
+
+        # Create a warning if interest is close to room capacity
+        if slot.room.capacity < slot.ak.interest + 5 or slot.room.capacity < slot.ak.interest * 1.25:
+            c = ConstraintViolation(
+                type=ConstraintViolation.ViolationType.ROOM_CAPACITY_EXCEEDED,
+                level=ConstraintViolation.ViolationLevel.WARNING,
+                event=slot.event,
+                room=slot.room,
+                comment=_("Space is too close to AK interest (Interest: %(interest)d, Capacity: %(capacity)d)")
+                        % {'interest': slot.ak.interest, 'capacity': slot.room.capacity}
+            )
+            c.ak_slots_tmp.add(slot)
+            c.aks_tmp.add(slot.ak)
+            return c
+
+    return None
+
+
+@receiver(post_save, sender=AK)
+def ak_changed_handler(sender, instance: AK, **kwargs):
+    """
+    Signal receiver: Check for violations after AK changed
+
+    Changes might affect: Reso intention, Category, Interest
+    """
+    # TODO Reso intention changes
+
+    # Check room capacities
+    violation_type = ConstraintViolation.ViolationType.ROOM_CAPACITY_EXCEEDED
+    new_violations = []
+    for slot in instance.akslot_set.all():
+        cv = check_capacity_for_slot(slot)
+        if cv is not None:
+            new_violations.append(cv)
+
+    existing_violations_to_check = list(instance.constraintviolation_set.filter(type=violation_type))
+    update_constraint_violations(new_violations, existing_violations_to_check)
+
+
+@receiver(m2m_changed, sender=AK.owners.through)
+def ak_owners_changed_handler(sender, instance: AK, action: str, **kwargs):
+    """
+    Signal receiver: Owners of AK changed
+    """
+    # Only signal after change (post_add, post_delete, post_clear) are relevant
+    if not action.startswith("post"):
+        return
+
+    event = instance.event
+
+    # Owner(s) changed: Might affect multiple AKs by the same owner(s) at the same time
+    violation_type = ConstraintViolation.ViolationType.OWNER_TWO_SLOTS
+    new_violations = []
+
+    slots_of_this_ak: [AKSlot] = instance.akslot_set.filter(start__isnull=False)
+
+    # For all owners (after recent change)...
+    for owner in instance.owners.all():
+        # ...find other slots that might be overlapping...
+
+        for ak in owner.ak_set.all():
+            # ...find overlapping slots...
+            if ak != instance:
+                for slot in slots_of_this_ak:
+                    for other_slot in ak.akslot_set.filter(start__isnull=False):
+                        if slot.overlaps(other_slot):
+                            # ...and create a temporary violation if necessary...
+                            c = ConstraintViolation(
+                                type=violation_type,
+                                level=ConstraintViolation.ViolationLevel.VIOLATION,
+                                event=event,
+                                ak_owner=owner
+                            )
+                            c.aks_tmp.add(instance)
+                            c.aks_tmp.add(other_slot.ak)
+                            c.ak_slots_tmp.add(slot)
+                            c.ak_slots_tmp.add(other_slot)
+                            new_violations.append(c)
+
+    # ... and compare to/update list of existing violations of this type
+    # belonging to the AK that was recently changed (important!)
+    existing_violations_to_check = list(instance.constraintviolation_set.filter(type=violation_type))
+    # print(existing_violations_to_check)
+    update_constraint_violations(new_violations, existing_violations_to_check)
+
+
+@receiver(m2m_changed, sender=AK.conflicts.through)
+def ak_conflicts_changed_handler(sender, instance: AK, action: str, **kwargs):
+    """
+    Signal receiver: Conflicts of AK changed
+    """
+    # Only signal after change (post_add, post_delete, post_clear) are relevant
+    if not action.startswith("post"):
+        return
+
+    event = instance.event
+
+    # Conflict(s) changed: Might affect multiple AKs that are conflicts of each other
+    violation_type = ConstraintViolation.ViolationType.AK_CONFLICT_COLLISION
+    new_violations = []
+
+    slots_of_this_ak: [AKSlot] = instance.akslot_set.filter(start__isnull=False)
+    conflicts_of_this_ak: [AK] = instance.conflicts.all()
+
+    # Loop over all existing conflicts
+    for ak in conflicts_of_this_ak:
+        if ak != instance:
+            for other_slot in ak.akslot_set.filter(start__isnull=False):
+                for slot in slots_of_this_ak:
+                    # ...find overlapping slots...
+                    if slot.overlaps(other_slot):
+                        # ...and create a temporary violation if necessary...
+                        c = ConstraintViolation(
+                            type=violation_type,
+                            level=ConstraintViolation.ViolationLevel.VIOLATION,
+                            event=event,
+                        )
+                        c.aks_tmp.add(instance)
+                        c.ak_slots_tmp.add(slot)
+                        c.ak_slots_tmp.add(other_slot)
+                        new_violations.append(c)
+
+    # ... and compare to/update list of existing violations of this type
+    # belonging to the AK that was recently changed (important!)
+    existing_violations_to_check = list(instance.constraintviolation_set.filter(type=violation_type))
+    # print(existing_violations_to_check)
+    update_constraint_violations(new_violations, existing_violations_to_check)
+
+
+@receiver(m2m_changed, sender=AK.prerequisites.through)
+def ak_prerequisites_changed_handler(sender, instance: AK, action: str, **kwargs):
+    """
+    Signal receiver: Prerequisites of AK changed
+    """
+    # Only signal after change (post_add, post_delete, post_clear) are relevant
+    if not action.startswith("post"):
+        return
+
+    event = instance.event
+
+    # Prerequisite(s) changed: Might affect multiple AKs that should have a certain order
+    violation_type = ConstraintViolation.ViolationType.AK_BEFORE_PREREQUISITE
+    new_violations = []
+
+    slots_of_this_ak: [AKSlot] = instance.akslot_set.filter(start__isnull=False)
+    prerequisites_of_this_ak: [AK] = instance.prerequisites.all()
+
+    # Loop over all prerequisites
+    for ak in prerequisites_of_this_ak:
+        if ak != instance:
+            for other_slot in ak.akslot_set.filter(start__isnull=False):
+                for slot in slots_of_this_ak:
+                    # ...find overlapping slots...
+                    if other_slot.end > slot.start:
+                        # ...and create a temporary violation if necessary...
+                        c = ConstraintViolation(
+                            type=violation_type,
+                            level=ConstraintViolation.ViolationLevel.VIOLATION,
+                            event=event,
+                        )
+                        c.aks_tmp.add(instance)
+                        c.ak_slots_tmp.add(slot)
+                        c.ak_slots_tmp.add(other_slot)
+                        new_violations.append(c)
+
+    # ... and compare to/update list of existing violations of this type
+    # belonging to the AK that was recently changed (important!)
+    existing_violations_to_check = list(instance.constraintviolation_set.filter(type=violation_type))
+    # print(existing_violations_to_check)
+    update_constraint_violations(new_violations, existing_violations_to_check)
+
+
+@receiver(m2m_changed, sender=AK.requirements.through)
+def ak_requirements_changed_handler(sender, instance: AK, action: str, **kwargs):
+    """
+    Signal receiver: Requirements of AK changed
+    """
+    # Only signal after change (post_add, post_delete, post_clear) are relevant
+    if not action.startswith("post"):
+        return
+
+    event = instance.event
+
+    # Requirement(s) changed: Might affect slots and rooms
+    violation_type = ConstraintViolation.ViolationType.REQUIRE_NOT_GIVEN
+    new_violations = []
+
+    slots_of_this_ak: [AKSlot] = instance.akslot_set.filter(start__isnull=False)
+
+    # For all requirements (after recent change)...
+    for slot in slots_of_this_ak:
+
+        room = slot.room
+        if room is None:
+            continue
+        room_requirements = room.properties.all()
+
+        for requirement in instance.requirements.all():
+
+            if not requirement in room_requirements:
+                # ...and create a temporary violation if necessary...
+                c = ConstraintViolation(
+                    type=violation_type,
+                    level=ConstraintViolation.ViolationLevel.VIOLATION,
+                    event=event,
+                    requirement=requirement,
+                    room=room,
+                )
+                c.aks_tmp.add(instance)
+                c.ak_slots_tmp.add(slot)
+                new_violations.append(c)
+
+    # ... and compare to/update list of existing violations of this type
+    # belonging to the AK that was recently changed (important!)
+    existing_violations_to_check = list(instance.constraintviolation_set.filter(type=violation_type))
+    # print(existing_violations_to_check)
+    update_constraint_violations(new_violations, existing_violations_to_check)
+
+
+@receiver(post_save, sender=AKSlot)
+def akslot_changed_handler(sender, instance: AKSlot, **kwargs):
+    """
+    Signal receiver: AKSlot changed
+
+    Changes might affect: Duplicate parallel, Two in room, Resodeadline
+    """
+    # TODO Consider rewriting this very long and complex method to resolve several (style) issues:
+    # pylint: disable=too-many-nested-blocks,too-many-locals,too-many-branches,too-many-statements
+    event = instance.event
+
+    # == Check for two parallel slots by one of the owners ==
+
+    violation_type = ConstraintViolation.ViolationType.OWNER_TWO_SLOTS
+    new_violations = []
+
+    if instance.start:
+        # For all owners (after recent change)...
+        for owner in instance.ak.owners.all():
+            # ...find other slots that might be overlapping...
+
+            for ak in owner.ak_set.all():
+                # ...find overlapping slots...
+                if ak != instance.ak:
+                    for other_slot in ak.akslot_set.filter(start__isnull=False):
+                        if instance.overlaps(other_slot):
+                            # ...and create a temporary violation if necessary...
+                            c = ConstraintViolation(
+                                type=violation_type,
+                                level=ConstraintViolation.ViolationLevel.VIOLATION,
+                                event=event,
+                                ak_owner=owner
+                            )
+                            c.aks_tmp.add(instance.ak)
+                            c.aks_tmp.add(other_slot.ak)
+                            c.ak_slots_tmp.add(instance)
+                            c.ak_slots_tmp.add(other_slot)
+                            new_violations.append(c)
+
+    # ... and compare to/update list of existing violations of this type
+    # belonging to the AK that was recently changed (important!)
+    existing_violations_to_check = list(instance.constraintviolation_set.filter(type=violation_type))
+    # print(existing_violations_to_check)
+    update_constraint_violations(new_violations, existing_violations_to_check)
+
+    # == Check for two aks in the same room at the same time ==
+
+    violation_type = ConstraintViolation.ViolationType.ROOM_TWO_SLOTS
+    new_violations = []
+
+    # For all slots in this room...
+    if instance.room and instance.start:
+        for other_slot in instance.room.akslot_set.filter(start__isnull=False):
+            if other_slot != instance:
+                # ... find overlapping slots...
+                if instance.overlaps(other_slot):
+                    # ...and create a temporary violation if necessary...
+                    c = ConstraintViolation(
+                        type=violation_type,
+                        level=ConstraintViolation.ViolationLevel.WARNING,
+                        event=event,
+                        room=instance.room
+                    )
+                    c.aks_tmp.add(instance.ak)
+                    c.aks_tmp.add(other_slot.ak)
+                    c.ak_slots_tmp.add(instance)
+                    c.ak_slots_tmp.add(other_slot)
+                    new_violations.append(c)
+
+    # ... and compare to/update list of existing violations of this type
+    # belonging to the slot that was recently changed (important!)
+    existing_violations_to_check = list(instance.constraintviolation_set.filter(type=violation_type))
+    # print(existing_violations_to_check)
+    update_constraint_violations(new_violations, existing_violations_to_check)
+
+    # == Check for reso ak after reso deadline ==
+
+    update_cv_reso_deadline_for_slot(instance)
+
+    # == Check for two slots of the same AK at the same time (warning) ==
+
+    violation_type = ConstraintViolation.ViolationType.AK_SLOT_COLLISION
+    new_violations = []
+
+    if instance.start:
+        # For all other slots of this ak...
+        for other_slot in instance.ak.akslot_set.filter(start__isnull=False):
+            if other_slot != instance:
+                # ... find overlapping slots...
+                if instance.overlaps(other_slot):
+                    # ...and create a temporary violation if necessary...
+                    c = ConstraintViolation(
+                        type=violation_type,
+                        level=ConstraintViolation.ViolationLevel.WARNING,
+                        event=event,
+                    )
+                    c.aks_tmp.add(instance.ak)
+                    c.ak_slots_tmp.add(instance)
+                    c.ak_slots_tmp.add(other_slot)
+                    new_violations.append(c)
+
+    # ... and compare to/update list of existing violations of this type
+    # belonging to the slot that was recently changed (important!)
+    existing_violations_to_check = list(instance.constraintviolation_set.filter(type=violation_type))
+    update_constraint_violations(new_violations, existing_violations_to_check)
+
+    # == Check for slot outside availability ==
+
+    # An AK's availability changed: Might affect AK slots scheduled outside the permitted time
+    violation_type = ConstraintViolation.ViolationType.SLOT_OUTSIDE_AVAIL
+    new_violations = []
+
+    if instance.start:
+        availabilities_of_this_ak: [Availability] = instance.ak.availabilities.all()
+
+        covered = False
+
+        for availability in availabilities_of_this_ak:
+            covered = availability.start <= instance.start and availability.end >= instance.end
+            if covered:
+                break
+        if not covered:
+            c = ConstraintViolation(
+                type=violation_type,
+                level=ConstraintViolation.ViolationLevel.VIOLATION,
+                event=event
+            )
+            c.aks_tmp.add(instance.ak)
+            c.ak_slots_tmp.add(instance)
+            new_violations.append(c)
+
+    # ... and compare to/update list of existing violations of this type
+    # belonging to the AK that was recently changed (important!)
+    existing_violations_to_check = list(instance.constraintviolation_set.filter(type=violation_type))
+    # print(existing_violations_to_check)
+    update_constraint_violations(new_violations, existing_violations_to_check)
+
+    # == Check for requirement not fulfilled by room ==
+
+    # Room(s) changed: Might affect slots and rooms
+    violation_type = ConstraintViolation.ViolationType.REQUIRE_NOT_GIVEN
+    new_violations = []
+
+    if instance.room:
+
+        room_requirements = instance.room.properties.all()
+
+        for requirement in instance.ak.requirements.all():
+
+            if requirement not in room_requirements:
+                # ...and create a temporary violation if necessary...
+                c = ConstraintViolation(
+                    type=violation_type,
+                    level=ConstraintViolation.ViolationLevel.VIOLATION,
+                    event=event,
+                    requirement=requirement,
+                    room=instance.room,
+                )
+                c.aks_tmp.add(instance.ak)
+                c.ak_slots_tmp.add(instance)
+                new_violations.append(c)
+
+    # ... and compare to/update list of existing violations of this type
+    # belonging to the AK that was recently changed (important!)
+    existing_violations_to_check = list(instance.constraintviolation_set.filter(type=violation_type))
+    # print(existing_violations_to_check)
+    update_constraint_violations(new_violations, existing_violations_to_check)
+
+    # == check for simultaneous slots of conflicting AKs ==
+
+    violation_type = ConstraintViolation.ViolationType.AK_CONFLICT_COLLISION
+    new_violations = []
+
+    if instance.start:
+        conflicts_of_this_ak: [AK] = instance.ak.conflicts.all()
+
+        for ak in conflicts_of_this_ak:
+            if ak != instance.ak:
+                for other_slot in ak.akslot_set.filter(start__isnull=False):
+                    # ...find overlapping slots...
+                    if instance.overlaps(other_slot):
+                        # ...and create a temporary violation if necessary...
+                        c = ConstraintViolation(
+                            type=violation_type,
+                            level=ConstraintViolation.ViolationLevel.VIOLATION,
+                            event=event,
+                        )
+                        c.aks_tmp.add(instance.ak)
+                        c.ak_slots_tmp.add(instance)
+                        c.ak_slots_tmp.add(other_slot)
+                        new_violations.append(c)
+
+    # ... and compare to/update list of existing violations of this type
+    # belonging to the AK that was recently changed (important!)
+    existing_violations_to_check = list(instance.ak.constraintviolation_set.filter(type=violation_type))
+    # print(existing_violations_to_check)
+    update_constraint_violations(new_violations, existing_violations_to_check)
+
+    # == check for missing prerequisites ==
+
+    violation_type = ConstraintViolation.ViolationType.AK_BEFORE_PREREQUISITE
+    new_violations = []
+
+    if instance.start:
+        prerequisites_of_this_ak: [AK] = instance.ak.prerequisites.all()
+
+        for ak in prerequisites_of_this_ak:
+            if ak != instance.ak:
+                for other_slot in ak.akslot_set.filter(start__isnull=False):
+                    # ...find slots in the wrong order...
+                    if other_slot.end > instance.start:
+                        # ...and create a temporary violation if necessary...
+                        c = ConstraintViolation(
+                            type=violation_type,
+                            level=ConstraintViolation.ViolationLevel.VIOLATION,
+                            event=event,
+                        )
+                        c.aks_tmp.add(instance.ak)
+                        c.ak_slots_tmp.add(instance)
+                        c.ak_slots_tmp.add(other_slot)
+                        new_violations.append(c)
+
+    # ... and compare to/update list of existing violations of this type
+    # belonging to the AK that was recently changed (important!)
+    existing_violations_to_check = list(instance.ak.constraintviolation_set.filter(type=violation_type))
+    # print(existing_violations_to_check)
+    update_constraint_violations(new_violations, existing_violations_to_check)
+
+    # == Check for room capacity ==
+    cv = check_capacity_for_slot(instance)
+    new_violations = [cv] if cv is not None else []
+
+    # Compare to/update list of existing violations of this type for this slot
+    existing_violations_to_check = list(
+        instance.constraintviolation_set.filter(type=ConstraintViolation.ViolationType.ROOM_CAPACITY_EXCEEDED)
+    )
+    update_constraint_violations(new_violations, existing_violations_to_check)
+
+
+@receiver(pre_delete, sender=AKSlot)
+def akslot_deleted_handler(sender, instance: AKSlot, **kwargs):
+    """
+    Signal receiver: AKSlot deleted
+
+    Manually clean up or remove constraint violations that belong to this slot since there is no cascade deletion
+    for many2many relationships. Explicitly listening for AK deletion signals is not necessary since they will
+    transitively trigger this signal and we always set both AK and AKSlot references in a constraint violation
+    """
+    # print(f"{instance} deleted")
+
+    for cv in instance.constraintviolation_set.all():
+        # Make sure not delete CVs that e.g., show three parallel slots in a single room
+        if cv.ak_slots.count() <= 2:
+            cv.delete()
+
+
+@receiver(post_save, sender=Room)
+def room_changed_handler(sender, instance: Room, **kwargs):
+    """
+    Signal receiver: Room changed
+
+    Changes might affect: Room size
+    """
+    # Check room capacities
+    violation_type = ConstraintViolation.ViolationType.ROOM_CAPACITY_EXCEEDED
+    new_violations = []
+    for slot in instance.akslot_set.all():
+        cv = check_capacity_for_slot(slot)
+        if cv is not None:
+            new_violations.append(cv)
+
+    existing_violations_to_check = list(instance.constraintviolation_set.filter(type=violation_type))
+    update_constraint_violations(new_violations, existing_violations_to_check)
+
+
+@receiver(m2m_changed, sender=Room.properties.through)
+def room_requirements_changed_handler(sender, instance: Room, action: str, **kwargs):
+    """
+    Signal Receiver: Requirements of room changed
+    """
+    # Only signal after change (post_add, post_delete, post_clear) are relevant
+    if not action.startswith("post"):
+        return
+
+    # event = instance.event
+    # TODO React to changes
+
+
+@receiver(post_save, sender=Availability)
+def availability_changed_handler(sender, instance: Availability, **kwargs):
+    """
+    Signal receiver: Availalability changed
+
+    Changes might affect: category availability, AK availability, Room availability
+    """
+    event = instance.event
+
+    # An AK's availability changed: Might affect AK slots scheduled outside the permitted time
+    if instance.ak:
+        violation_type = ConstraintViolation.ViolationType.SLOT_OUTSIDE_AVAIL
+        new_violations = []
+
+        availabilities_of_this_ak: [Availability] = instance.ak.availabilities.all()
+        slots_of_this_ak: [AKSlot] = instance.ak.akslot_set.filter(start__isnull=False)
+
+        for slot in slots_of_this_ak:
+            covered = False
+            for availability in availabilities_of_this_ak:
+                covered = availability.start <= slot.start and availability.end >= slot.end
+                if covered:
+                    break
+            if not covered:
+                c = ConstraintViolation(
+                    type=violation_type,
+                    level=ConstraintViolation.ViolationLevel.VIOLATION,
+                    event=event
+                )
+                c.aks_tmp.add(instance.ak)
+                c.ak_slots_tmp.add(slot)
+                new_violations.append(c)
+
+        # ... and compare to/update list of existing violations of this type
+        # belonging to the AK that was recently changed (important!)
+        existing_violations_to_check = list(instance.ak.constraintviolation_set.filter(type=violation_type))
+        # print(existing_violations_to_check)
+        update_constraint_violations(new_violations, existing_violations_to_check)
+
+
+@receiver(post_save, sender=Event)
+def event_changed_handler(sender, instance: Event, **kwargs):
+    """
+    Signal receiver: Event changed
+
+    Changes might affect: Reso deadline
+    """
+    # Check for reso ak after reso deadline (which might have changed)
+    if instance.reso_deadline:
+        for slot in instance.akslot_set.filter(start__isnull=False, ak__reso=True):
+            update_cv_reso_deadline_for_slot(slot)
+    else:
+        # No reso deadline, delete all violations
+        violation_type = ConstraintViolation.ViolationType.AK_AFTER_RESODEADLINE
+        existing_violations_to_check = list(instance.constraintviolation_set.filter(type=violation_type))
+        update_constraint_violations([], existing_violations_to_check)

AKScheduling/static/AKScheduling/js/scheduling.js

+function loadCVs(url, callback_success, callback_error) {
+    $.ajax({
+        url: url,
+        type: 'GET',
+        success: callback_success,
+        error: callback_error
+    });
+}
+
+const default_cv_callback_error = function(response) {
+   alert("{% trans 'Cannot load current violations from server' %}");
+}

AKScheduling/static/AKScheduling/vendor/dragula/dragula.css

+.gu-mirror {
+  position: fixed !important;
+  margin: 0 !important;
+  z-index: 9999 !important;
+  opacity: 0.8;
+  -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=80)";
+  filter: alpha(opacity=80);
+}
+.gu-hide {
+  display: none !important;
+}
+.gu-unselectable {
+  -webkit-user-select: none !important;
+  -moz-user-select: none !important;
+  -ms-user-select: none !important;
+  user-select: none !important;
+}
+.gu-transit {
+  opacity: 0.2;
+  -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=20)";
+  filter: alpha(opacity=20);
+}