Problem with ForeignKey to an abstract class
Ferran
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Hello everyone,
I want to have foreign keys to parent model on a manytomany
intermediate table (through) to have unique entries for that domain.
The problem is i want this parent model class to be an abstract one,
because i don't ever want to instantiate it, using DomainOwned or
DomainPending instead.
The error i'm getting is this:
File "/home/ferran/0_ubilibet/intranet/domains/models.py", line 48,
in ContactType
domain = models.ForeignKey(DomainUbi)
File
"/usr/lib/python2.7/site-packages/django/db/models/fields/related.py",
line 808, in __init__
assert not to._meta.abstract, "%s cannot define a relation with
abstract class %s" % (self.__class__.__name__, to._meta.object_name)
AssertionError: ForeignKey cannot define a relation with abstract
class DomainUbi
On both the foreignkeys to DomainUbi on models ContactType and
AssociatedNameServer.
I've thought maybe i can implement contacts and ns fields in both
DomainOwned and DomainPending, using generic relationships, but it
does not seems right to me.
Can anyone help me on this, please?
- ---
class DomainMinimal(models.Model):
sld = models.CharField(
max_length=63
)
tld = models.ForeignKey(common.Tld)
name = property('_domain_name')
def _domain_name(self):
return u'%s.%s' % (self.sld, self.tld)
def __unicode__(self):
return self.name
class Meta:
abstract = True
class DomainUbi(DomainMinimal):
owner = models.ForeignKey(contacts.Contact, related_name='Owner')
contacts = models.ManyToManyField(contacts.Contact,
through='ContactType')
ns = models.ManyToManyField('NameServer',
through='AssociatedNameServer')
period = models.IntegerField(validators=[MaxValueValidator(10)])
class Meta:
abstract = True
class DomainOwned(DomainUbi):
crdate = models.DateField()
exdate = models.DateField()
class DomainPending(DomainUbi):
status = None # just an example, now
class ContactType(models.Model):
contact = models.ForeignKey(contacts.Contact)
domain = models.ForeignKey(DomainUbi)
role = models.CharField(
max_length=10,
choices = (
('admin', 'Administratiu'),
('billing', 'Facturacio'),
('tech', 'Tecnic'),
)
)
class Meta:
unique_together = ('contact', 'domain', 'role')
class AssociatedNameServer(models.Model):
ns = models.ForeignKey('NameServer')
domain = models.ForeignKey(DomainUbi)
priority = models.IntegerField(
validators=[MaxValueValidator(4)]
)
def __unicode__(self):
return "%s (%s)" % (self.ns.host, self.ns.ip)
class Meta:
unique_together = ('ns', 'domain', 'priority')
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Ferran
Hash: SHA256
On 01/12/10 12:48, Ferran wrote:
> I've thought maybe i can implement contacts and ns fields in both
> DomainOwned and DomainPending, using generic relationships, but it
> does not seems right to me.
Shame on me.
This is the right way to do it, the only way, in fact.
I really want django to solve it with his own magic, but... no.
My solution:
# class DomainUbi
change:
contacts = models.ManyToManyField(
contacts.Contact,
through='ContactType'
)
to:
contacts = GenericRelation('ContactType')
# class ContactType
change:
domain = models.ForeignKey(DomainUbi)
to:
content_type = models.ForeignKey(ContentType)
object_id = models.PositiveIntegerField()
content_object = GenericForeignKey()
change:
unique_together = ('contact', 'domain', 'role')
to:
unique_together = ('contact', 'role', 'content_type', 'object_id')
Thank you!
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Marc Aymerich
Marc