Django中的通用一对一关系 [英] Generic one-to-one relation in Django
问题描述
我需要设置一对一的关系,也必须是通用的。可能你可以建议我一个更好的设计。到目前为止,我想到了以下模型:
I need to set up one-to-one relation which must also be generic. May be you can advice me a better design. So far I came up to the following models
class Event(models.Model):
# skip event related fields...
content_type = models.ForeignKey(ContentType)
object_id = models.PositiveIntegerField()
content_object = generic.GenericForeignKey('content_type', 'object_id')
class Meta:
unique_together = ('content_type', 'object_id')
class Action1(models.Model):
# skip action1 related fields...
events = generic.GenericRelation(Event, content_type_field='content_type', object_id_field='object_id')
@property
def event(self):
return self.events.get() # <<<<<< Is this reasonable?
class Action2(models.Model):...
在Django管理员在事件列表中我想收集所有的操作,从那里我想去管理页面的操作。是否可以避免在动作模型中创建事件
属性?有更好的解决方案吗?在单个定义中组合字段事件
和属性事件
将是很好的。我正在使用的项目使用Django 1.1
In Django Admin in event list I want to collect all actions, and from there I want go to admin pages for actions. Is it possible to avoid creating event
property in the action models? Is there a better solution? It would be nice to combine the field events
and the property event
in a single definition. The project I am working with uses Django 1.1
推荐答案
我最近遇到这个问题。你所做的一切都很好,但是您可以通过创建一个透明地反转关系的mixin来更广泛地使用它:
I recently came across this problem. What you have done is fine, but you can generalise it a little bit more by creating a mixin that reverses the relationship transparently:
class Event(models.Model):
content_type = models.ForeignKey(ContentType)
object_id = models.PositiveIntegerField()
content_object = generic.GenericForeignKey('content_type', 'object_id')
class Meta:
unique_together = ('content_type', 'object_id')
class EventMixin(object):
@property
def get_event(self):
ctype = ContentType.objects.get_for_model(self.__class__)
try:
event = Event.objects.get(content_type__pk = ctype.id, object_id=self.id)
except:
return None
return event
class Action1(EventMixin, models.Model):
# Don't need to mess up the models fields (make sure the mixing it placed before models.Model)
...
和
action = Action1.object.get(id=1)
event = action.get_event
您可能希望将缓存添加到反向关系中
You might want to add caching to the reverse relationship too
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