95 lines
3.0 KiB
Python
95 lines
3.0 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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`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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sorting_filters = ()
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# legacy support
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sortable_by = None
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sortable_foreign_key = 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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sortable_foreign_keys_length = len(sortable_foreign_keys)
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if sortable_foreign_keys_length > 1:
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raise MultipleSortableForeignKeyException(
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u'{0} may only have one SortableForeignKey'.format(self))
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elif sortable_foreign_keys_length == 1:
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self.__class__.sortable_foreign_key = sortable_foreign_keys[0]
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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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def _filter_objects(self, filters, extra_filters):
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if extra_filters:
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filters.update(extra_filters)
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if self.sortable_foreign_key:
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# sfk_obj == sortable foreign key instance
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sfk_obj = getattr(self, self.sortable_foreign_key.name)
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filters.update(
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{self.sortable_foreign_key.name: sfk_obj.id})
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try:
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obj = self._meta.model.objects.filter(**filters)[:1][0]
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except IndexError:
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obj = None
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return obj
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def get_next(self, extra_filters={}):
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return self._filter_objects({'order__gt': self.order},
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extra_filters)
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def get_previous(self, extra_filters={}):
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return self._filter_objects({'order__lt': self.order},
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extra_filters)
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