Hi, did you got any response or did you managed to solve your problem? I've just started to search for a UUIDField, and it would be great to have proper uuid columns for postgres.
If so do you plan to commit it to django_extensions? Thanks, Viktor On 2008 dec. 16, 22:53, gordyt <gor...@gmail.com> wrote: > Howdy Folks! > > I wanted to be able to have UUID primary keys for certain models. > I found the implementation done by the django_extensions project > (http://code.google.com/p/django-command-extensions/) and it works > fine > as is. > > But I wanted to be able to have a UUIDField that stored its values in > an > actual 'uuid' column if we were using PostgreSQL. For all other > databases > it would use the same char(36) field as in the original > implementation. > This was for performance reasons, by the way. > > So listed below was my attempt at creating a UUIDField (based on the > django_extensions one) that would do that. It works great in every > situation EXCEPT if I am working with a model that inherits from > another > model. > > Before I go any further, let me say that I've posted all of this > on a web site so that it can be seen with nicer formatting than what > is > possible in a newsgroup post. The URL for that page is: > > http://www.gordontillman.info/computers/41-django/94-django-uuidfield... > > -- or -- > > http://tinyurl.com/6rnsya > > I've included the complete UUIDField definition, some sample models, > and a small test case. > > Here is an interesting part. The to_python() method of the UUIDField > is supposed to return an instance of uuid.UUID. This is my original > implementation of that method: > > def to_python(self, value): > if not value: > return None > if isinstance(value, uuid.UUID): > return value > # attempt to parse a UUID > return uuid.UUID(smart_unicode(value)) > > This original implementation words great unless I'm working with a > model that inherits from a base model that uses the UUIDField as its > primary key. If I change the implementation to this then the test > case > passes, both for the base model and the inherited model. But of > course > now it is returning a string, not a uuid.UUID value. > > def to_python(self, value): > if not value: > return None > if isinstance(value, uuid.UUID): > return smart_unicode(value) > else: > return value > > I was wondering if anyone could suggest an improvement to my > UUIDField implementation so that (1) to_python() returns a proper > uuid.UUID instance and (2) I can still use 'uuid' columns in > databases that support it. > > It's possible there is a bug in the part of the Django code that > deals with inherited models, but I'm sure it's way more likely > that there is a bug in my UUIDField! > > ---------- begin UUIDField ---------- > import uuid > > from django.forms.util import ValidationError > from django import forms > from django.db import models > from django.utils.encoding import smart_unicode > from django.utils.translation import ugettext_lazy > > class UUIDVersionError(Exception): > pass > > class UUIDField(models.Field): > """Encode and stores a Python uuid.UUID in a manner that is > appropriate > for the given datatabase that we are using. > > For sqlite3 or MySQL we save it as a 36-character string value > For PostgreSQL we save it as a uuid field > > This class supports type 1, 2, 4, and 5 UUID's. > """ > __metaclass__ = models.SubfieldBase > > _CREATE_COLUMN_TYPES = { > 'postgresql_psycopg2': 'uuid', > 'postgresql': 'uuid' > } > > def __init__(self, verbose_name=None, name=None, auto=True, > version=1, > node=None, clock_seq=None, namespace=None, **kwargs): > """Contruct a UUIDField. > > @param verbose_name: Optional verbose name to use in place of > what > Django would assign. > @param name: Override Django's name assignment > @param auto: If True, create a UUID value if one is not > specified. > @param version: By default we create a version 1 UUID. > @param node: Used for version 1 UUID's. If not supplied, then > the > uuid.getnode() function is called to obtain it. This can > be slow. > @param clock_seq: Used for version 1 UUID's. If not supplied > a random > 14-bit sequence number is chosen > @param namespace: Required for version 3 and version 5 UUID's. > @param name: Required for version4 and version 5 UUID's. > > See Also: > - Python Library Reference, section 18.16 for more > information. > - RFC 4122, "A Universally Unique IDentifier (UUID) URN > Namespace" > > If you want to use one of these as a primary key for a Django > model, do this:: > id = UUIDField(primary_key=True) > This will currently I{not} work with Jython because PostgreSQL > support > in Jython is not working for uuid column types. > """ > self.max_length = 36 > kwargs['max_length'] = self.max_length > if auto: > kwargs['blank'] = True > kwargs.setdefault('editable', False) > > self.auto = auto > self.version = version > if version==1: > self.node, self.clock_seq = node, clock_seq > elif version==3 or version==5: > self.namespace, self.name = namespace, name > > super(UUIDField, self).__init__(verbose_name=verbose_name, > name=name, **kwargs) > > def create_uuid(self): > if not self.version or self.version==4: > return uuid.uuid4() > elif self.version==1: > return uuid.uuid1(self.node, self.clock_seq) > elif self.version==2: > raise UUIDVersionError("UUID version 2 is not supported.") > elif self.version==3: > return uuid.uuid3(self.namespace, self.name) > elif self.version==5: > return uuid.uuid5(self.namespace, self.name) > else: > raise UUIDVersionError("UUID version %s is not valid." % > self.version) > > def db_type(self): > from django.conf import settings > return UUIDField._CREATE_COLUMN_TYPES.get > (settings.DATABASE_ENGINE, > "char(%s)" % self.max_length) > > def to_python(self, value): > """Return a uuid.UUID instance from the value returned by the > database.""" > # > # This is the proper way... But this doesn't work correctly > when > # working with an inherited model > # > if not value: > return None > if isinstance(value, uuid.UUID): > return value > # attempt to parse a UUID > return uuid.UUID(smart_unicode(value)) > > # > # If I do the following (returning a String instead of a UUID > # instance), everything works. > # > > #if not value: > # return None > #if isinstance(value, uuid.UUID): > # return smart_unicode(value) > #else: > # return value > > def pre_save(self, model_instance, add): > if self.auto and add: > value = self.create_uuid() > setattr(model_instance, self.attname, value) > else: > value = super(UUIDField, self).pre_save(model_instance, > add) > if self.auto and not value: > value = self.create_uuid() > setattr(model_instance, self.attname, value) > return value > > def get_db_prep_value(self, value): > """Casts uuid.UUID values into the format expected by the back > end > for use in queries""" > if isinstance(value, uuid.UUID): > return smart_unicode(value) > return value > > def value_to_string(self, obj): > val = self._get_val_from_obj(obj) > if val is None: > data = '' > else: > data = smart_unicode(val) > return data > > def formfield(self, **kwargs): > defaults = { > 'form_class': forms.CharField, > 'max_length': self.max_length > } > defaults.update(kwargs) > return super(UUIDField, self).formfield(**defaults) > ---------- end UUIDField ---------- > > ---------- begin sample models ---------- > > from django.db import models > from fields import UUIDField > > class Customer(models.Model): > MAX_NAME_LEN = 200 > id = UUIDField(primary_key=True) > name = models.CharField(max_length=MAX_NAME_LEN) > > class User(models.Model): > MAX_FIRST_NAME = 32 > MAX_LAST_NAME = 32 > MAX_USERNAME = 32 > > id = UUIDField(primary_key=True) > customer = models.ForeignKey(Customer) > first_name = models.CharField(max_length=MAX_FIRST_NAME) > last_name = models.CharField(max_length=MAX_LAST_NAME) > username = models.CharField(max_length=MAX_USERNAME) > password = models.CharField(max_length=128, blank=True) > > class Teacher(User): > email = models.EmailField() > admin = models.BooleanField(default=False) > ---------- end sample models ---------- > > ---------- begin sample test ---------- > import logging > import random > import unittest > import time > import sys > from models import * > > class InheritanceTestCase(unittest.TestCase): > """ > python manage.py test hb7t.InheritanceTestCase > """ > > def runTest(self): > c = Customer(name='cust1') > c.save() > u = User(customer=c, first_name='f', last_name='l', > username='fl', > password='p') > u.save() > self.assertEqual(1, Customer.objects.count()) > self.assertEqual(1, User.objects.count()) > self.assertEqual(0, Teacher.objects.count()) > > t = Teacher(customer=c, first_name='g', last_name='t', > username='gt', > password='p', email=...@test.com') > # Everything passes up to this point, whether or not to_python > () returns > # a uuid.UUID value OR a string value > # But t.save() fails if to_python() returns a uuid.UUID value > t.save() > self.assertEqual(1, Customer.objects.count()) > self.assertEqual(2, User.objects.count()) > self.assertEqual(1, Teacher.objects.count()) > > c.delete() > self.assertEqual(0, Customer.objects.count()) > self.assertEqual(0, User.objects.count()) > self.assertEqual(0, Teacher.objects.count()) > > ---------- end sample test ---------- > > ERROR: runTest (kindle.hb7t.tests.InheritanceTestCase) > ---------------------------------------------------------------------- > Traceback (most recent call last): > File "/home/gordy/projects/kindle/../kindle/hb7t/tests.py", line > 118, in runTest > t.save() > File "/usr/local/lib/python2.5/site-packages/django/db/models/ > base.py", line 328, in save > self.save_base(force_insert=force_insert, > force_update=force_update) > File "/usr/local/lib/python2.5/site-packages/django/db/models/ > base.py", line 375, in save_base > manager.filter(pk=pk_val).extra(select={'a': 1}).values > ('a').order_by())): > File "/usr/local/lib/python2.5/site-packages/django/db/models/ > query.py", line 191, in __nonzero__ > iter(self).next() > File "/usr/local/lib/python2.5/site-packages/django/db/models/ > query.py", line 185, in _result_iter > self._fill_cache() > File "/usr/local/lib/python2.5/site-packages/django/db/models/ > query.py", line 618, in _fill_cache > self._result_cache.append(self._iter.next()) > File "/usr/local/lib/python2.5/site-packages/django/db/models/ > query.py", line 659, in iterator > for row in self.query.results_iter(): > File "/usr/local/lib/python2.5/site-packages/django/db/models/sql/ > query.py", line 203, in results_iter > for rows in self.execute_sql(MULTI): > File "/usr/local/lib/python2.5/site-packages/django/db/models/sql/ > query.py", line 1756, in execute_sql > cursor.execute(sql, params) > ProgrammingError: can't adapt --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. 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