71 lines
2.6 KiB
Python
71 lines
2.6 KiB
Python
from __future__ import unicode_literals
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import logging
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from django.contrib.contenttypes.fields import GenericForeignKey
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from django.contrib.contenttypes.models import ContentType
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from django.db import models
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from django.db.models import Max
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from django.utils.encoding import python_2_unicode_compatible
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from django.utils.translation import ugettext_lazy as _
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from .managers import TransformationManager
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from .transformations import BaseTransformation
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from .validators import YAMLValidator
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logger = logging.getLogger(__name__)
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@python_2_unicode_compatible
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class Transformation(models.Model):
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"""
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Model that stores the transformation and transformation arguments
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for a given object
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Fields:
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* order - Order of a Transformation - In case there are multiple
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transformations for an object, this field list the order at which
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they will be execute.
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* arguments - Arguments of a Transformation - An optional field to hold a
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transformation argument. Example: if a page is rotated with the Rotation
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transformation, this field will show by how many degrees it was rotated.
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"""
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content_type = models.ForeignKey(on_delete=models.CASCADE, to=ContentType)
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object_id = models.PositiveIntegerField()
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content_object = GenericForeignKey('content_type', 'object_id')
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order = models.PositiveIntegerField(
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blank=True, db_index=True, default=0, help_text=_(
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'Order in which the transformations will be executed. If left '
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'unchanged, an automatic order value will be assigned.'
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), verbose_name=_('Order')
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)
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name = models.CharField(
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choices=BaseTransformation.get_transformation_choices(),
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max_length=128, verbose_name=_('Name')
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)
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arguments = models.TextField(
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blank=True, help_text=_(
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'Enter the arguments for the transformation as a YAML '
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'dictionary. ie: {"degrees": 180}'
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), validators=[YAMLValidator()], verbose_name=_('Arguments')
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)
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objects = TransformationManager()
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class Meta:
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ordering = ('order',)
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unique_together = ('content_type', 'object_id', 'order')
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verbose_name = _('Transformation')
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verbose_name_plural = _('Transformations')
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def __str__(self):
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return self.get_name_display()
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def save(self, *args, **kwargs):
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if not self.order:
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last_order = Transformation.objects.filter(
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content_type=self.content_type, object_id=self.object_id
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).aggregate(Max('order'))['order__max']
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if last_order is not None:
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self.order = last_order + 1
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super(Transformation, self).save(*args, **kwargs)
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