Resolve "Do not allow to add personal notes for cancelled lessons"

Closes #82 (closed)

aleksis/apps/alsijil/migrations/0002_excuse_type.py

+# Generated by Django 3.0.8 on 2020-07-10 10:46
+
+import django.contrib.postgres.fields.jsonb
+import django.contrib.sites.managers
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("sites", "0002_alter_domain_unique"),
+        ("alsijil", "0001_initial"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="ExcuseType",
+            fields=[
+                (
+                    "id",
+                    models.AutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                (
+                    "extended_data",
+                    django.contrib.postgres.fields.jsonb.JSONField(
+                        default=dict, editable=False
+                    ),
+                ),
+                (
+                    "short_name",
+                    models.CharField(
+                        max_length=255, unique=True, verbose_name="Short name"
+                    ),
+                ),
+                (
+                    "name",
+                    models.CharField(max_length=255, unique=True, verbose_name="Name"),
+                ),
+                (
+                    "site",
+                    models.ForeignKey(
+                        default=1,
+                        editable=False,
+                        on_delete=django.db.models.deletion.CASCADE,
+                        to="sites.Site",
+                    ),
+                ),
+            ],
+            options={
+                "verbose_name": "Excuse type",
+                "verbose_name_plural": "Excuse types",
+                "ordering": ["name"],
+            },
+            managers=[("objects", django.contrib.sites.managers.CurrentSiteManager()),],
+        ),
+        migrations.AddField(
+            model_name="personalnote",
+            name="excuse_type",
+            field=models.ForeignKey(
+                blank=True,
+                null=True,
+                on_delete=django.db.models.deletion.SET_NULL,
+                to="alsijil.ExcuseType",
+                verbose_name="Excuse type",
+            ),
+        ),
+    ]