mirror of
https://github.com/Hopiu/django-model-utils.git
synced 2026-03-16 20:00:23 +00:00
118 lines
3.8 KiB
Python
118 lines
3.8 KiB
Python
from datetime import datetime
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from django.db import models
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from django.contrib.contenttypes.models import ContentType
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from django.utils.translation import ugettext_lazy as _
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from django.db.models.fields import FieldDoesNotExist
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from django.core.exceptions import ImproperlyConfigured
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from model_utils.managers import QueryManager
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from model_utils.fields import AutoCreatedField, AutoLastModifiedField, \
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StatusField, MonitorField
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class InheritanceCastModel(models.Model):
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"""
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An abstract base class that provides a ``real_type`` FK to ContentType.
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For use in trees of inherited models, to be able to downcast
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parent instances to their child types.
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"""
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real_type = models.ForeignKey(ContentType, editable=False, null=True)
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def save(self, *args, **kwargs):
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if not self.id:
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self.real_type = self._get_real_type()
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super(InheritanceCastModel, self).save(*args, **kwargs)
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def _get_real_type(self):
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return ContentType.objects.get_for_model(type(self))
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def cast(self):
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return self.real_type.get_object_for_this_type(pk=self.pk)
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class Meta:
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abstract = True
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class TimeStampedModel(models.Model):
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"""
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An abstract base class model that provides self-updating
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``created`` and ``modified`` fields.
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"""
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created = AutoCreatedField(_('created'))
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modified = AutoLastModifiedField(_('modified'))
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class Meta:
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abstract = True
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class TimeFramedModel(models.Model):
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"""
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An abstract base class model that provides ``start``
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and ``end`` fields to record a timeframe.
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"""
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start = models.DateTimeField(_('start'), null=True, blank=True)
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end = models.DateTimeField(_('end'), null=True, blank=True)
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class Meta:
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abstract = True
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class StatusModel(models.Model):
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"""
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An abstract base class model with a ``status`` field that
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automatically uses a ``STATUS`` class attribute of choices, a
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``status_changed`` date-time field that records when ``status``
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was last modified, and an automatically-added manager for each
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status that returns objects with that status only.
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"""
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status = StatusField(_('status'))
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status_changed = MonitorField(_('status changed'), monitor='status')
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class Meta:
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abstract = True
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def add_status_query_managers(sender, **kwargs):
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"""
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Add a Querymanager for each status item dynamically.
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"""
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if not issubclass(sender, StatusModel):
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return
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for value, name in getattr(sender, 'STATUS', ()):
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try:
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sender._meta.get_field(name)
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raise ImproperlyConfigured("StatusModel: Model '%s' has a field "
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"named '%s' which conflicts with a "
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"status of the same name."
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% (sender.__name__, name))
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except FieldDoesNotExist:
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pass
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sender.add_to_class(value, QueryManager(status=value))
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def add_timeframed_query_manager(sender, **kwargs):
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"""
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Add a QueryManager for a specific timeframe.
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"""
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if not issubclass(sender, TimeFramedModel):
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return
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try:
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sender._meta.get_field('timeframed')
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raise ImproperlyConfigured("Model '%s' has a field named "
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"'timeframed' which conflicts with "
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"the TimeFramedModel manager."
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% sender.__name__)
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except FieldDoesNotExist:
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pass
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sender.add_to_class('timeframed', QueryManager(
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(models.Q(start__lte=datetime.now) | models.Q(start__isnull=True)) &
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(models.Q(end__gte=datetime.now) | models.Q(end__isnull=True))
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))
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models.signals.class_prepared.connect(add_status_query_managers)
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models.signals.class_prepared.connect(add_timeframed_query_manager)
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