Source code for scripts.unique_slugify
"""
See http://djangosnippets.org/snippets/690/
"""
import re
from django.template.defaultfilters import slugify
[docs]def unique_slugify(instance, value, slug_field_name='slug', queryset=None,
slug_separator='-', case='lower'):
"""
Calculates and stores a unique slug of ``value`` for an instance.
``slug_field_name`` should be a string matching the name of the field to
store the slug in (and the field to check against for uniqueness).
``queryset`` usually doesn't need to be explicitly provided - it'll default
to using the ``.all()`` queryset from the model's default manager.
"""
slug_field = instance._meta.get_field(slug_field_name)
slug = getattr(instance, slug_field.attname)
slug_len = slug_field.max_length
# Sort out the initial slug, limiting its length if necessary.
slug = slugify(value)
if case == 'upper':
slug = slug.upper()
if slug_len:
slug = slug[:slug_len]
slug = _slug_strip(slug, slug_separator)
original_slug = slug
# Create the queryset if one wasn't explicitly provided and exclude the
# current instance from the queryset.
if queryset is None:
queryset = instance.__class__._default_manager.all()
if instance.pk:
queryset = queryset.exclude(pk=instance.pk)
# Find a unique slug. If one matches, at '-2' to the end and try again
# (then '-3', etc).
next = 2
while not slug or queryset.filter(**{slug_field_name: slug}):
slug = original_slug
end = '%s%s' % (slug_separator, next)
if slug_len and len(slug) + len(end) > slug_len:
slug = slug[:slug_len-len(end)]
slug = _slug_strip(slug, slug_separator)
slug = '%s%s' % (slug, end)
next += 1
setattr(instance, slug_field.attname, slug)
def _slug_strip(value, separator='-'):
"""
Cleans up a slug by removing slug separator characters that occur at the
beginning or end of a slug.
If an alternate separator is used, it will also replace any instances of
the default '-' separator with the new separator.
"""
separator = separator or ''
if separator == '-' or not separator:
re_sep = '-'
else:
re_sep = '(?:-|%s)' % re.escape(separator)
# Remove multiple instances and if an alternate separator is provided,
# replace the default '-' separator.
if separator != re_sep:
value = re.sub('%s+' % re_sep, separator, value)
# Remove separator from the beginning and end of the slug.
if separator:
if separator != '-':
re_sep = re.escape(separator)
value = re.sub(r'^%s+|%s+$' % (re_sep, re_sep), '', value)
return value