mirror of
https://github.com/Hopiu/django-model-utils.git
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27 lines
841 B
Python
27 lines
841 B
Python
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from django.db import models
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from django.contrib.contenttypes.models import ContentType
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class InheritanceCastModel(models.Model):
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"""
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An abstract base class that provides a ``real_type`` FK to ContentType.
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For use in trees of inherited models, to be able to downcast
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parent instances to their child types.
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"""
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real_type = models.ForeignKey(ContentType, editable=False, null=True)
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def save(self, *args, **kwargs):
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if not self.id:
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self.real_type = self._get_real_type()
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super(InheritanceCastModel, self).save(*args, **kwargs)
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def _get_real_type(self):
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return ContentType.objects.get_for_model(type(self))
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def cast(self):
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return self.real_type.get_object_for_this_type(pk=self.pk)
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class Meta:
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abstract = True
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