make datamigration for non-unique slugs, test the migration

categories/migrations/0005_unique_category_slug.py

@@ -2,14 +2,32 @@
 
 from django.db import migrations, models
 
+from categories.models import Category
+
+
+def make_slugs_unique(apps, schema_editor):
+    duplicates = Category.tree.values("slug").annotate(slug_count=models.Count("slug")).filter(slug_count__gt=1)
+    category_objs = []
+    for duplicate in duplicates:
+        slug = duplicate["slug"]
+        categories = Category.tree.filter(slug=slug)
+        count = categories.count()
+        i = 0
+        for category in categories.all():
+            if i != 0:
+                category.slug = "{}-{}".format(slug, str(i).zfill(len(str(count))))
+                category_objs.append(category)
+            i += 1
+    Category.objects.bulk_update(category_objs, ["slug"])
+
 
 class Migration(migrations.Migration):
-
     dependencies = [
         ("categories", "0004_auto_20200517_1832"),
     ]
 
     operations = [
+        migrations.RunPython(make_slugs_unique, reverse_code=migrations.RunPython.noop),
         migrations.AlterField(
             model_name="category",
             name="slug",

categories/tests/test_migrations.py

@@ -0,0 +1,42 @@
+import sys
+
+if sys.version_info >= (3, 0):
+    from django_test_migrations.contrib.unittest_case import MigratorTestCase
+
+    class TestMigrations(MigratorTestCase):
+        migrate_from = ("categories", "0004_auto_20200517_1832")
+        migrate_to = ("categories", "0005_unique_category_slug")
+
+        def prepare(self):
+            Category = self.old_state.apps.get_model("categories", "Category")
+            Category.tree.create(slug="foo", lft=0, rght=0, tree_id=0, level=0)
+            Category.tree.create(slug="foo", lft=0, rght=0, tree_id=0, level=0)
+            Category.tree.create(slug="foo", lft=0, rght=0, tree_id=0, level=0)
+            for i in range(1, 12):
+                Category.tree.create(slug="bar", lft=0, rght=0, tree_id=0, level=0)
+            Category.tree.create(slug="baz", lft=0, rght=0, tree_id=0, level=0)
+            assert Category.tree.count() == 15
+
+        def test_unique_slug_migration(self):
+            Category = self.new_state.apps.get_model("categories", "Category")
+
+            self.assertListEqual(
+                list(Category.tree.values_list("slug", flat=True)),
+                [
+                    "foo",
+                    "foo-1",
+                    "foo-2",
+                    "bar",
+                    "bar-01",
+                    "bar-02",
+                    "bar-03",
+                    "bar-04",
+                    "bar-05",
+                    "bar-06",
+                    "bar-07",
+                    "bar-08",
+                    "bar-09",
+                    "bar-10",
+                    "baz",
+                ],
+            )

tox.ini

@@ -37,6 +37,11 @@ deps=
     pillow
     ipdb
     codecov
+    django-test-migrations
+    django21: django-test-migrations<=1.2.0
+    django22: django-test-migrations<=1.2.0
+    django3: django-test-migrations<=1.2.0
+    django31: django-test-migrations<=1.2.0
     -r{toxinidir}/requirements.txt
 
 commands=