"""

base abstract models

"""

import uuid

from concurrency.fields import AutoIncVersionField

from django.db import models

from django.utils.translation import ugettext_lazy as _

class ModelManager(models.Manager):

    def get_by_natural_key(self, ext_id):

        return self.get(ext_id=ext_id)

class Model(models.Model):

    objects = ModelManager()

    created = models.DateTimeField(auto_now_add=True, verbose_name=_('Model|created'))

    updated = models.DateTimeField(auto_now=True, verbose_name=_('Model|updated'))

    ext_id = models.UUIDField(unique=True, default=uuid.uuid4, verbose_name=_('Model|ext_id'))

    version = AutoIncVersionField(verbose_name=_('Model|version'))

    def natural_key(self):

        return (self.ext_id, )

    class Meta:

        abstract = True