你可以通过手动创建消息和收件人之间的连接表来使用通用关系来实现此目的：
from django.db import models
from django.contrib.contenttypes import generic
from django.contrib.contenttypes.models import ContentType
class Client(models.Model):
city = models.CharField(max_length=16)
# These aren't required, but they'll allow you do cool stuff
# like "person.sent_messages.all()" to get all messages sent
# by that person, and "person.received_messages.all()" to
# get all messages sent to that person.
# Well...sort of, since "received_messages.all()" will return
# a queryset of "MessageRecipient" instances.
sent_messages = generic.GenericRelation('Message',
content_type_field='sender_content_type',
object_id_field='sender_id'
)
received_messages = generic.GenericRelation('MessageRecipient',
content_type_field='recipient_content_type',
object_id_field='recipient_id'
)
class Meta:
abstract = True
class PersonClient(Client):
first_name = models.CharField(max_length=16)
last_name = models.CharField(max_length=16)
gender = models.CharField(max_length=1)
def __unicode__(self):
return u'%s %s' % (self.last_name, self.first_name)
class CompanyClient(Client):
name = models.CharField(max_length=32)
tax_no = models.PositiveIntegerField()
def __unicode__(self):
return self.name
class Message(models.Model):
sender_content_type = models.ForeignKey(ContentType)
sender_id = models.PositiveIntegerField()
sender = generic.GenericForeignKey('sender_content_type', 'sender_id')
msg_body = models.CharField(max_length=1024)
def __unicode__(self):
return u'%s...' % self.msg_body[:25]
class MessageRecipient(models.Model):
message = models.ForeignKey(Message)
recipient_content_type = models.ForeignKey(ContentType)
recipient_id = models.PositiveIntegerField()
recipient = generic.GenericForeignKey('recipient_content_type', 'recipient_id')
def __unicode__(self):
return u'%s sent to %s' % (self.message, self.recipient)
你将像这样使用以上模型：
>>> person1 = PersonClient.objects.create(first_name='Person', last_name='One', gender='M')
>>> person2 = PersonClient.objects.create(first_name='Person', last_name='Two', gender='F')
>>> company = CompanyClient.objects.create(name='FastCompany', tax_no='4220')
>>> company_ct = ContentType.objects.get_for_model(CompanyClient)
>>> person_ct = ContentType.objects.get_for_model(person1) # works for instances too.
# Now we create a message:
>>> msg = Message.objects.create(sender_content_type=person_ct, sender_id=person1.pk, msg_body='Hey, did any of you move my cheese?')
# and send it to a coupla recipients:
>>> MessageRecipient.objects.create(message=msg, recipient_content_type=person_ct, recipient_id=person2.pk)
>>> MessageRecipient.objects.create(message=msg, recipient_content_type=company_ct, recipient_id=company.pk)
>>> MessageRecipient.objects.count()
2
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