Link substitutions to week number and period.

biscuit/apps/chronos/migrations/0004_auto_20190821_1550.py

+# Generated by Django 2.2.4 on 2019-08-21 15:50
+
+import biscuit.apps.chronos.util
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('chronos', '0003_lesson_substitution'),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name='lessonperiod',
+            name='substitution',
+        ),
+        migrations.AddField(
+            model_name='lessonsubstitution',
+            name='lesson_period',
+            field=models.ForeignKey(default=1, on_delete=django.db.models.deletion.CASCADE, related_name='substitutions', to='chronos.LessonPeriod'),
+            preserve_default=False,
+        ),
+        migrations.AddField(
+            model_name='lessonsubstitution',
+            name='week',
+            field=models.IntegerField(default=biscuit.apps.chronos.util.current_week, verbose_name='Kalenderwoche'),
+        ),
+    ]

biscuit/apps/chronos/models.py

@@ -2,6 +2,8 @@ from django.core import validators
 from django.db import models
 from django.utils.translation import ugettext_lazy as _
 
+from .util import current_week
+
 
 class TimePeriod(models.Model):
     WEEKDAY_CHOICES = [
@@ -82,24 +84,25 @@ class LessonPeriod(models.Model):
 
     room = models.ForeignKey('Room', models.CASCADE, null=True)
 
-    substitution = models.OneToOneField('LessonSubstitution', models.CASCADE,
-                                        related_name='lesson_period', null=True)
+    def get_substitution(self, week=None):
+        wanted_week = week or current_week()
+        return self.substitutions.filter(week=wanted_week).first()
 
     def get_subject(self):
-        if self.substitution:
-            return self.substitution.subject
+        if self.get_substitution():
+            return self.get_substitution().subject
         else:
             return self.lesson.subject
 
     def get_teachers(self):
-        if self.substitution:
-            return self.substitution.teachers
+        if self.get_substitution():
+            return self.get_substitution().teachers
         else:
             return self.lesson.teachers
 
     def get_room(self):
-        if self.substitution:
-            return self.substitution.room
+        if self.get_substitution():
+            return self.get_substitution().room
         else:
             return self.room
 
@@ -108,6 +111,12 @@ class LessonPeriod(models.Model):
 
 
 class LessonSubstitution(models.Model):
+    week = models.IntegerField(verbose_name=_('Kalenderwoche'),
+                               default=current_week)
+
+    lesson_period = models.ForeignKey(
+        'LessonPeriod', models.CASCADE, 'substitutions')
+
     subject = models.ForeignKey(
         'Subject', on_delete=models.CASCADE,
         related_name='lesson_substitutions', null=True)

biscuit/apps/chronos/util.py

+from datetime import datetime
+
+
+def current_week():
+    return int(datetime.now().strftime('%V'))

biscuit/apps/chronos/views.py

@@ -9,6 +9,7 @@ from biscuit.core.decorators import admin_required
 from biscuit.core.models import Group, Person
 
 from .models import LessonPeriod, TimePeriod, Room
+from .util import current_week
 
 
 @login_required
@@ -73,5 +74,6 @@ def timetable(request):
     context['filter_descs'] = ', '.join(filter_descs)
     context['periods'] = TimePeriod.get_times_dict()
     context['weekdays'] = dict(TimePeriod.WEEKDAY_CHOICES)
+    context['current_week'] = current_week()
 
     return render(request, 'chronos/tt_week.html', context)