Add 'wagtailcategories' to your INSTALLED_APPS.
In your app (eg: demo), you can add a category and register to wagtail admin interface.
from wagtailcategories.models import BaseCategory, register_category
@register_category
class ProductCategory(BaseCategory):
some_field = models.CharField(max_length=100)
class Meta:
verbose_name='Product Category'
verbose_name_plural='Product Categories'
# using south
./manage.py schemamigration demo --auto
# or django migrations
./manage.py makemigrations demo
# migrate
./manage.py migrate demo