Split remove_filter_model migration to prevent Postgres errors - fixes #2754

wagtail/wagtailimages/migrations/0014_remove_filter_model.py

@@ -1,56 +0,0 @@
-# -*- coding: utf-8 -*-
-from __future__ import unicode_literals
-
-from django.db import migrations, models
-
-
-def forwards_data_migration(apps, schema_editor):
-    Rendition = apps.get_model('wagtailimages', 'Rendition')
-    db_alias = schema_editor.connection.alias
-    # update doesn't work during migration, we have to do it one by one
-    for rendition in Rendition.objects.using(db_alias).select_related('filter').all():
-        rendition.filter2 = rendition.filter.spec
-        rendition.save()
-
-
-def reverse_data_migration(apps, schema_editor):
-    Rendition = apps.get_model('wagtailimages', 'Rendition')
-    Filter = apps.get_model('wagtailimages', 'Filter')
-    db_alias = schema_editor.connection.alias
-    renditions = Rendition.objects.using(db_alias).all()
-    for rendition in renditions:
-        # Ensure we don't create the same Filter twice
-        rendition.filter, _ = Filter.objects.get_or_create(spec=rendition.filter2)
-        rendition.save()
-
-
-class Migration(migrations.Migration):
-
-    dependencies = [
-        ('wagtailimages', '0013_make_rendition_upload_callable'),
-    ]
-
-    operations = [
-        # We create a new attribute to allow the data migration (filter -> filter2).
-        migrations.AddField(
-            model_name='Rendition',
-            name='filter2',
-            field=models.CharField(max_length=255, default=''),
-            preserve_default=False,
-        ),
-        # Allow NULL for backward operation to work (no temporary default value possible as the `spec` attribute is not null but also unique).
-        migrations.AlterField('rendition', 'filter', models.ForeignKey(on_delete=models.CASCADE, related_name='+', to='wagtailimages.Filter', null=True)),
-        # Remove unique constraint to allow the removal of `filter` field.
-        migrations.AlterUniqueTogether('rendition', set([])),
-        # Migrate data.
-        migrations.RunPython(forwards_data_migration, reverse_data_migration),
-        # We can now delete Filter for good.
-        migrations.RemoveField(model_name='Rendition', name='filter'),
-        migrations.DeleteModel('Filter'),
-        # And we can finally set the new attribute as `filter`.
-        migrations.RenameField(model_name='Rendition', old_name='filter2', new_name='filter'),
-        # Bug with mysql and postgresql, we need to add the index after the renaming (https://code.djangoproject.com/ticket/25530).
-        migrations.AlterField('rendition', 'filter', models.CharField(max_length=255, db_index=True)),
-        # We can now set back the unique constraint.
-        migrations.AlterUniqueTogether('rendition', set([('image', 'filter', 'focal_point_key')])),
-    ]

wagtail/wagtailimages/migrations/0014_remove_filter_model_1.py

@@ -0,0 +1,25 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('wagtailimages', '0013_make_rendition_upload_callable'),
+    ]
+
+    operations = [
+        # We create a new attribute to allow the data migration (filter -> filter2).
+        migrations.AddField(
+            model_name='Rendition',
+            name='filter2',
+            field=models.CharField(max_length=255, default=''),
+            preserve_default=False,
+        ),
+        # Allow NULL for backward operation to work (no temporary default value possible as the `spec` attribute is not null but also unique).
+        migrations.AlterField('rendition', 'filter', models.ForeignKey(on_delete=models.CASCADE, related_name='+', to='wagtailimages.Filter', null=True)),
+        # Remove unique constraint to allow the removal of `filter` field.
+        migrations.AlterUniqueTogether('rendition', set([])),
+    ]

wagtail/wagtailimages/migrations/0015_remove_filter_model_2.py

@@ -0,0 +1,36 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+def forwards_data_migration(apps, schema_editor):
+    Rendition = apps.get_model('wagtailimages', 'Rendition')
+    db_alias = schema_editor.connection.alias
+    # update doesn't work during migration, we have to do it one by one
+    for rendition in Rendition.objects.using(db_alias).select_related('filter').all():
+        rendition.filter2 = rendition.filter.spec
+        rendition.save()
+
+
+def reverse_data_migration(apps, schema_editor):
+    Rendition = apps.get_model('wagtailimages', 'Rendition')
+    Filter = apps.get_model('wagtailimages', 'Filter')
+    db_alias = schema_editor.connection.alias
+    renditions = Rendition.objects.using(db_alias).all()
+    for rendition in renditions:
+        # Ensure we don't create the same Filter twice
+        rendition.filter, _ = Filter.objects.get_or_create(spec=rendition.filter2)
+        rendition.save()
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('wagtailimages', '0014_remove_filter_model_1'),
+    ]
+
+    operations = [
+        # Migrate data.
+        migrations.RunPython(forwards_data_migration, reverse_data_migration),
+    ]

wagtail/wagtailimages/migrations/0016_remove_filter_model_3.py

@@ -0,0 +1,23 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('wagtailimages', '0015_remove_filter_model_2'),
+    ]
+
+    operations = [
+        # We can now delete Filter for good.
+        migrations.RemoveField(model_name='Rendition', name='filter'),
+        migrations.DeleteModel('Filter'),
+        # And we can finally set the new attribute as `filter`.
+        migrations.RenameField(model_name='Rendition', old_name='filter2', new_name='filter'),
+        # Bug with mysql and postgresql, we need to add the index after the renaming (https://code.djangoproject.com/ticket/25530).
+        migrations.AlterField('rendition', 'filter', models.CharField(max_length=255, db_index=True)),
+        # We can now set back the unique constraint.
+        migrations.AlterUniqueTogether('rendition', set([('image', 'filter', 'focal_point_key')])),
+    ]