Hi,
I need an educated opinion on the following idea. It's supposed to
provide a (very-)weakly coupled architecture where any object that
inherits from ExtendableModel can be said to relate to one or many
objects that also inherit from it. This way I want to achieve at least
two things:
(1) No need to hard-code relationships
(2) As a consequence of (1) no need to reconstruct the tables every
time I want to add a new relationship
I think this is not a very bad idea, but maybe technically there are
better ways to implement this. Or, maybe, it IS a bad idea
altogether? :)
Also - how is it (if at all) possible to still use the admin interface
with this kind of architecture?
The code is below - thanks for any comments!
Thanks,
Igor
____________________________________________________
from django.db import models
from django.contrib.contenttypes import generic
from django.contrib.contenttypes.models import ContentType
class ExtendableModel(models.Model):
id = models.AutoField(primary_key=True)
extendable_content_type = models.ForeignKey(ContentType)
extendable_object_id = models.PositiveIntegerField()
extendable_content_object = generic.GenericForeignKey
('extension_content_type', 'extension_object_id')
def __init__(self, *args, **kwargs):
super(ExtendableModel, self).__init__(self, args, kwargs)
self.extendable_content_type_id = int
(ContentType.objects.get_for_model(self).id)
print type(self.extendable_content_type_id)
def get_related(self, model_class): # Returns objects of type
model_class that extend self
ContentType.objects.get_for_model(b)
return model_class.objects.filter(
extendable_content_type__pk=ContentType.objects.get_for_model
(self).id,
extendable_object_id=self.id)
____________________________________________________
Sample usage:
class Entry(ExtendableModel):
title = models.TextField(editable=False, blank=True)
...
class Event(ExtendableModel):
start_datetime = models.DateTimeField
(default=datetime.datetime.now)
end_datetime = models.DateTimeField(default=datetime.datetime.now)
____________________________________________________
entry = Entry(title="A blog post")
event = Event(start_datetime=somestime1, end_datetime_sometime2)
entry.associate(event) # suppose this is how actual object-to-object
relationships
# are added - haven't thought this
thru
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