make Category.slug unique

README.rst

@@ -13,6 +13,12 @@ Django Categories grew out of our need to provide a basic hierarchical taxonomy
 
 As a news site, our stories, photos, and other content get divided into "sections" and we wanted all the apps to use the same set of sections. As our needs grew, the Django Categories grew in the functionality it gave to category handling within web pages.
 
+=======
+New in 2.0
+==========
+
+*  Category.slug becomes unique. You must remove all duplicates in category slugs before running migrations.
+
 New in 1.4
 ==========
 

categories/base.py

@@ -44,7 +44,7 @@ class CategoryBase(MPTTModel):
         verbose_name=_('parent'),
     )
     name = models.CharField(max_length=100, verbose_name=_('name'))
-    slug = models.SlugField(verbose_name=_('slug'))
+    slug = models.SlugField(verbose_name=_('slug'), unique=True)
     active = models.BooleanField(default=True, verbose_name=_('active'))
 
     objects = CategoryManager()

categories/migrations/0003_auto_20181005_1559.py

@@ -0,0 +1,18 @@
+# Generated by Django 2.0.9 on 2018-10-05 13:59
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('categories', '0002_auto_20170217_1111'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='category',
+            name='slug',
+            field=models.SlugField(unique=True, verbose_name='slug'),
+        ),
+    ]