kopia lustrzana https://github.com/rtts/django-simplecms
75 wiersze
2.3 KiB
Python
75 wiersze
2.3 KiB
Python
class EasilyMigratable:
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"""
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Mixin for model fields. Prevents the generation of migrations that
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don't affect the database.
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"""
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def deconstruct(self):
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name, path, args, kwargs = super().deconstruct()
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for field in [
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"blank",
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"choices",
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"editable",
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"help_text",
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"limit_choices_to",
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"related_name",
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"storage",
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"upload_to",
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"validators",
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"verbose_name",
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]:
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if field in kwargs:
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del kwargs[field]
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return name, path, args, kwargs
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class Numbered:
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"""
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Mixin for numbered models. Overrides the save() method to
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automatically renumber all instances returned by
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number_with_respect_to()
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"""
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def number_with_respect_to(self):
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return self.__class__.objects.all()
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def get_field_name(self):
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return self.__class__._meta.ordering[-1].lstrip("-")
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def _renumber(self):
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"""Renumbers the queryset while preserving the instance's number"""
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queryset = self.number_with_respect_to()
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field_name = self.get_field_name()
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this_nr = getattr(self, field_name)
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if this_nr is None:
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this_nr = len(queryset) + 1
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# The algorithm: loop over the queryset and set each object's
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# number to the counter. When an object's number equals the
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# number of this instance, set this instance's number to the
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# counter, increment the counter by 1, and finish the loop
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counter = 1
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inserted = False
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for other in queryset.exclude(pk=self.pk):
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other_nr = getattr(other, field_name)
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if counter >= this_nr and not inserted:
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setattr(self, field_name, counter)
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inserted = True
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counter += 1
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if other_nr != counter:
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setattr(other, field_name, counter)
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super(Numbered, other).save()
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counter += 1
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if not inserted:
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setattr(self, field_name, counter)
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def save(self, *args, **kwargs):
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self._renumber()
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super().save(*args, **kwargs)
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def delete(self, *args, **kwargs):
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setattr(self, self.get_field_name(), 9999) # hack
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self._renumber()
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super().delete(*args, **kwargs)
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