migration 0195 is invertible again

heltour/tournament/migrations/0195_remove_registration_fields.py

@@ -1,6 +1,6 @@
 # Generated by Django 2.2.28 between 2023-03-12 17:28 and 2023-03-22 13:58
 
-from django.db import migrations
+from django.db import migrations, models
 
 
 class Migration(migrations.Migration):
@@ -9,7 +9,24 @@ class Migration(migrations.Migration):
         ('tournament', '0194_playerpairing_last_time_player_changed'),
     ]
 
+
     operations = [
+        # Altering some fields to add defaults before removing them, so the deletions are invertible
+        migrations.AlterField(
+            model_name='registration',
+            name='classical_rating',
+            field=models.PositiveIntegerField(verbose_name='rating', default=0),
+        ),
+        migrations.AlterField(
+            model_name='registration',
+            name='peak_classical_rating',
+            field=models.PositiveIntegerField(blank=True, null=True, verbose_name='peak rating', default=0),
+        ),
+        migrations.AlterField(
+            model_name='registration',
+            name='already_in_slack_group',
+            field=models.BooleanField(default=False),
+        ),
         migrations.RemoveField(
             model_name='registration',
             name='classical_rating',