Usually users' profiles are stored in single model. When there are multiple user types, separation is made by some field like user_type.
Situation is a little more complicated when different data is needed for each user type.
Of course it's better when all users have same type and are granted different permissions. But since we got task to have separate user types - we'll have to solve it.
Simple solution
The most obvious solution is to make base profile with type identifier, which will pull needed model instance:
request.user.get_profile().get_final_profile()But I don't really like this solution. Firstly, get_final_profile method is basically a big switch-case. Secondly - we must not forget to call extra method.
I wanted to simply write request.user.profile ans get needed profile instance. This is possible by combining two known tricks - Upcast and AutoOneToOneField.
Upcast
Allows to get sublass instance from base class instance.
AutoOneToOneField
Allows creating related objects on request. This field is not needed per se, only idea. Taking AutoOneToOneField as a base, it's easy to create a new one that calls upcast when related objects is requested.
Solution
class UpCastModel(models.Model):
"""
Base class for models that are ment to be inherited.
Introduces upcast method that returns child instance.
"""
final_type = models.ForeignKey(ContentType, editable=False)
def save(self, args, **kwargs):
if not self.pk:
self.final_type = ContentType.objects.get_for_model(type(self))
super(UpCastModel, self).save(args, **kwargs)
def upcast(self):
if not hasattr(self, '_upcast'):
if self.final_type.model_class == self.class:
self._upcast = self
else:
self._upcast = self.final_type.get_object_for_this_type(id=self.pk)
return self._upcast
class Meta:
abstract = True
class UpCastSingleRelatedObjectDescriptor(SingleRelatedObjectDescriptor):
def get(self, instance, instance_type=None):
parent = super(
UpCastSingleRelatedObjectDescriptor, self
).get(instance, instance_type)
return parent.upcast()
class UpCastOneToOneField(models.OneToOneField):
"""
UpCastOneToOneField gets child of related object.
"""
def contribute_to_related_class(self, cls, related):
setattr(
cls, related.get_accessor_name(),
UpCastSingleRelatedObjectDescriptor(related)
)
Now profile looks like this:
class BaseProfile(UpcastModel):
user = UpCastOneToOneField(User)
class BoyProfile(BaseProfile):
pass
class GirlProfile(CitizenProfile):
passIn order to get users, profile, we just need to write requst.user.profile.
Subscribe for the news and updates
Programmatic generation of PDF files is a frequent task when developing applications that can export reports, bills, or questionnaires. In this article, we will consider three common tools for creating PDFs, including their installation and converting principles.
Protection of WEB App is of paramount importance and it should be afforded the same level of security as the intellectual rights or private property. I'm going to cover how to protect your web app.
In this article we'll research how to pass custom markup to Angular components and how to create different types of dynamic components.
This article is aimed for beginners, who are trying to choose between Ruby on Rails and Django. Let’s see which is fastest and why.
In this article I will tell you how to create an interactive interface with a widely customized visual look and different filtering to view reports.
It appears that not everyone knows that in python you can create classes dynamically without metaclasses. I'll show an example of how to do it.So we've learned how to use custom QuerySet to chain requests:Article.objects.old().public()Now we need to make it work for related objects:user.articles.old().public()This is done using use_for_related_fields, but it needs a little trick.