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import shortuuid
import sys
from django.db.models import CharField
class ShortUUIDField(CharField):
"""
A field which stores a Short UUID value in base57 format. This may also have
the Boolean attribute 'auto' which will set the value on initial save to a
new UUID value (calculated using shortuuid's default (uuid4)). Note that while all
UUIDs are expected to be unique we enforce this with a DB constraint.
"""
def __init__(self, auto=True, *args, **kwargs):
self.auto = auto
# We store UUIDs in base57 format, which is fixed at 22 characters.
kwargs['max_length'] = 22
if auto:
# Do not let the user edit UUIDs if they are auto-assigned.
kwargs['editable'] = False
kwargs['blank'] = True
# kwargs['unique'] = True # if you want to be paranoid, set unique=True in your instantiation of the field.
super(ShortUUIDField, self).__init__(*args, **kwargs)
def pre_save(self, model_instance, add):
"""
This is used to ensure that we auto-set values if required.
See CharField.pre_save
"""
value = super(ShortUUIDField, self).pre_save(model_instance, add)
if self.auto and not value:
# Assign a new value for this attribute if required.
if sys.version_info < (3, 0):
value = unicode(shortuuid.uuid())
else:
value = str(shortuuid.uuid())
setattr(model_instance, self.attname, value)
return value
def formfield(self, **kwargs):
if self.auto:
return None
return super(ShortUUIDField, self).formfield(**kwargs)
try:
from south.modelsinspector import add_introspection_rules
add_introspection_rules([], [r"^shortuuidfield\.fields\.ShortUUIDField"])
except ImportError:
pass
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