46 lines
1.4 KiB
Python
46 lines
1.4 KiB
Python
# Caching accessor for the reverse of a ForeignKey relatinoship
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# Started by axiak on #django
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class FKAsOneToOne(object):
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def __init__(self, field, reverse = False, query = None):
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self.field = field
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self.reverse = reverse
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self.query = query
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def __get_attr(self, instance):
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if self.reverse:
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field_name = '%s_set' % self.field
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else:
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field_name = self.field
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return getattr(instance, field_name)
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def __get__(self, instance, Model):
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if not hasattr(instance, '_field_values'):
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instance._field_values = {}
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try:
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return instance._field_values[self.field]
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except KeyError:
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pass
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if self.reverse:
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value_set = self.__get_attr(instance).all()
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if self.query:
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value_set = value_set.filter(self.query)
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try:
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instance._field_values[self.field] = value_set[0]
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except IndexError:
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instance._field_values[self.field] = None
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else:
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instance._field_values[self.field] = self.__get_attr(instance)
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return instance._field_values[self.field]
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def __set__(self, instance, value):
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if self.reverse:
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# this is dangerous
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#other_instance = self.__get_attr(instance).all()[0]
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#setattr(other_instance, self.field, value)
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#other_instance.save()
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raise NotImplemented
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else:
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setattr(instance, self.field, value)
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