agendas: clean db unique constraint for event slug (#41180)

chrono/agendas/migrations/0041_clean_event_slug_unicity.py

@@ -0,0 +1,38 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+import django
+from django.db import migrations
+
+
+def clean_constraint(apps, schema_editor):
+    Event = apps.get_model('agendas', 'Event')
+    if django.VERSION < (2, 0):
+        model = Event
+    else:
+        model = 'agendas_event'
+    # remove _like index added for unicity if exists
+    index_to_remove = schema_editor._create_index_name(model, ['slug'], suffix='_like')
+    index_names = schema_editor._constraint_names(Event, ['slug'], index=True)
+    for index_name in index_names:
+        if index_name == index_to_remove:
+            schema_editor.execute(
+                schema_editor._delete_constraint_sql(schema_editor.sql_delete_index, Event, index_name)
+            )
+    # remove unique constraint if exists
+    constraint_names = schema_editor._constraint_names(Event, ['slug'], unique=True)
+    for constraint_name in constraint_names:
+        schema_editor.execute(
+            schema_editor._delete_constraint_sql(schema_editor.sql_delete_unique, Event, constraint_name)
+        )
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('agendas', '0040_timeperiod_agenda'),
+    ]
+
+    operations = [
+        migrations.RunPython(clean_constraint, migrations.RunPython.noop),
+    ]