Add a migration script to fix duplicated categories during database setup

src/agenda_culturel/migrations/0108_remove_duplicated_categories.py

@@ -0,0 +1,44 @@
+# Generated by Django 4.2.9 on 2024-11-11 10:15
+
+from django.db import migrations
+
+
+def remove_duplicated_categories(apps, schema_editor):
+    Category = apps.get_model("agenda_culturel", "Category")
+    CategorisationRule = apps.get_model("agenda_culturel", "CategorisationRule")
+    Event = apps.get_model("agenda_culturel", "Event")
+
+
+    catnames = list(set([c.name for c in Category.objects.all()]))
+
+    # for each category name
+    for cname in catnames:
+        # check if it exists more than one category
+        if Category.objects.filter(name=cname).count() > 1:
+            cats = Category.objects.filter(name=cname).order_by("pk")
+            nbs = [Event.objects.filter(category=c).count() + CategorisationRule.objects.filter(category=c).count() for c in cats]
+
+            # if only one category with this name has elements
+            if len([n for n in nbs if n != 0]) == 1:
+                # remove all categories without elements
+                for n, c in zip(nbs, cats):
+                    if n == 0:
+                        c.delete()
+            else:
+                # otherwise, remove all but the last one (by ID)
+                for c in cats[0:-1]:
+                    c.delete()
+
+
+def do_nothing(apps, schema_editor):
+    pass
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('agenda_culturel', '0107_strip_aliases'),
+    ]
+
+    operations = [
+        migrations.RunPython(remove_duplicated_categories, reverse_code=do_nothing)
+    ]