67 lines
2.1 KiB
Python
67 lines
2.1 KiB
Python
from django.contrib.contenttypes.models import ContentType
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from django.db import models
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from adminsortable.fields import SortableForeignKey
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class MultipleSortableForeignKeyException(Exception):
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def __init__(self, value):
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self.value = value
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def __str__(self):
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return repr(self.value)
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class Sortable(models.Model):
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"""
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Unfortunately, Django doesn't support using more than one AutoField
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in a model or this class could be simplified.
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`is_sortable` determines whether or not the Model is sortable by
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determining if the last value of `order` is greater than the default
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of 1, which should be present if there is only one object.
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`model_type_id` returns the ContentType.id for the Model that
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inherits Sortable
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`save` the override of save increments the last/highest value of
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order by 1
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"""
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order = models.PositiveIntegerField(editable=False, default=1,
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db_index=True)
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is_sortable = False
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# legacy support
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sortable_by = None
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class Meta:
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abstract = True
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ordering = ['order']
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@classmethod
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def model_type_id(cls):
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return ContentType.objects.get_for_model(cls).id
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def __init__(self, *args, **kwargs):
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super(Sortable, self).__init__(*args, **kwargs)
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# Validate that model only contains at most one SortableForeignKey
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sortable_foreign_keys = []
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for field in self._meta.fields:
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if isinstance(field, SortableForeignKey):
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sortable_foreign_keys.append(field)
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if len(sortable_foreign_keys) > 1:
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raise MultipleSortableForeignKeyException(
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u'{} may only have one SortableForeignKey'.format(self))
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def save(self, *args, **kwargs):
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if not self.id:
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try:
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self.order = self.__class__.objects.aggregate(
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models.Max('order'))['order__max'] + 1
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except (TypeError, IndexError):
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pass
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super(Sortable, self).save(*args, **kwargs)
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