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from django.db import models
from django.utils.translation import ugettext_lazy as _
from django.utils.encoding import smart_unicode
CONTENT_TYPE_CACHE = {}
class ContentTypeManager(models.Manager):
def get_for_model(self, model):
"""
Returns the ContentType object for the given model, creating the
ContentType if necessary.
"""
opts = model._meta
key = (opts.app_label, opts.object_name.lower())
try:
ct = CONTENT_TYPE_CACHE[key]
except KeyError:
# The smart_unicode() is needed around opts.verbose_name_raw because it might
# be a django.utils.functional.__proxy__ object.
ct, created = self.model._default_manager.get_or_create(app_label=key[0],
model=key[1], defaults={'name': smart_unicode(opts.verbose_name_raw)})
CONTENT_TYPE_CACHE[key] = ct
return ct
def clear_cache(self):
"""
Clear out the content-type cache. This needs to happen during database
flushes to prevent caching of "stale" content type IDs (see
django.contrib.contenttypes.management.create_contenttypes for where
this gets called).
"""
global CONTENT_TYPE_CACHE
CONTENT_TYPE_CACHE = {}
class ContentType(models.Model):
name = models.CharField(maxlength=100)
app_label = models.CharField(maxlength=100)
model = models.CharField(_('python model class name'), maxlength=100)
objects = ContentTypeManager()
class Meta:
verbose_name = _('content type')
verbose_name_plural = _('content types')
db_table = 'django_content_type'
ordering = ('name',)
unique_together = (('app_label', 'model'),)
def __unicode__(self):
return self.name
def model_class(self):
"Returns the Python model class for this type of content."
from django.db import models
return models.get_model(self.app_label, self.model)
def get_object_for_this_type(self, **kwargs):
"""
Returns an object of this type for the keyword arguments given.
Basically, this is a proxy around this object_type's get_object() model
method. The ObjectNotExist exception, if thrown, will not be caught,
so code that calls this method should catch it.
"""
return self.model_class()._default_manager.get(**kwargs)
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