feat: store and update last_visit in person model

app/base/migrations/0005_person_last_visit.py

@@ -0,0 +1,48 @@
+# Generated by Django 4.2 on 2023-06-08 08:07
+
+from django.db import migrations
+from app.base.forms.fields import DateField
+from datetime import date
+
+
+def calc_last_visit(apps, schema_editor):
+    Person = apps.get_model('base', 'Person')
+    Booking = apps.get_model('base', 'Booking')
+    CourseVisit = apps.get_model('base', 'CourseVisit')
+
+    max_dates = {}
+    zero = date.fromtimestamp(0)
+
+    for (pk, day) in Booking.objects.values_list('user', 'begin_time__date'):
+        max_dates[pk] = max(day, max_dates.get(pk, zero))
+
+    for (pk1, pk2, day) in CourseVisit.objects.values_list(
+            'participant', 'teacher', 'date'):
+        max_dates[pk1] = max(day, max_dates.get(pk1, zero))
+        max_dates[pk2] = max(day, max_dates.get(pk2, zero))
+
+    for person in Person.objects.all():
+        person.last_visit = max(person.created, max_dates.get(person.pk, zero))
+        person.save()
+
+
+def noop(apps, schema_editor):
+    pass  # allow reverse migrate because field will be just deleted
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('base', '0004_person_created_merge_street'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='person',
+            name='last_visit',
+            field=DateField(verbose_name='Letzter Besuch', editable=False,
+                            default=date.fromtimestamp(0)),
+            preserve_default=False,
+        ),
+        migrations.RunPython(calc_last_visit, noop),
+    ]