62 lines
1.8 KiB
Python
62 lines
1.8 KiB
Python
import sys
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from django.contrib.contenttypes.models import ContentType
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from django.db import DEFAULT_DB_ALIAS
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def reset_polymorphic_ctype(*models, **filters):
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"""
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Set the polymorphic content-type ID field to the proper model
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Sort the ``*models`` from base class to descending class,
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to make sure the content types are properly assigned.
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Add ``preserve_existing=True`` to skip models which already
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have a polymorphic content type.
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"""
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using = filters.pop('using', DEFAULT_DB_ALIAS)
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ignore_existing = filters.pop('ignore_existing', False)
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models = sort_by_subclass(*models)
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if ignore_existing:
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# When excluding models, make sure we don't ignore the models we
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# just assigned the an content type to. hence, start with child first.
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models = reversed(models)
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for new_model in models:
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new_ct = ContentType.objects.db_manager(using).get_for_model(new_model)
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qs = new_model.objects.db_manager(using)
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if ignore_existing:
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qs = qs.filter(polymorphic_ctype__isnull=True)
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if filters:
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qs = qs.filter(**filters)
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qs.update(polymorphic_ctype=new_ct)
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def _compare_mro(cls1, cls2):
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if cls1 is cls2:
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return 0
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try:
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index1 = cls1.mro().index(cls2)
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except ValueError:
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return -1 # cls2 not inherited by 1
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try:
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index2 = cls2.mro().index(cls1)
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except ValueError:
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return 1 # cls1 not inherited by 2
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return (index1 > index2) - (index1 < index2) # python 3 compatible cmp.
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def sort_by_subclass(*classes):
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"""
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Sort a series of models by their inheritance order.
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"""
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if sys.version_info[0] == 2:
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return sorted(classes, cmp=_compare_mro)
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else:
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from functools import cmp_to_key
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return sorted(classes, key=cmp_to_key(_compare_mro))
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