102 lines
3.0 KiB
Python
102 lines
3.0 KiB
Python
from __future__ import unicode_literals
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import django
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from django.db import models
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from django.utils.translation import ugettext_lazy as _
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from django.core.exceptions import ImproperlyConfigured
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if django.VERSION >= (1, 9, 0):
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from django.db.models.functions import Now
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now = Now()
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else:
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from django.utils.timezone import now
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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 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, display in getattr(sender, 'STATUS', ()):
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if _field_exists(sender, value):
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raise ImproperlyConfigured(
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"StatusModel: Model '%s' has a field named '%s' which "
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"conflicts with a status of the same name."
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% (sender.__name__, value)
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)
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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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if _field_exists(sender, 'timeframed'):
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raise ImproperlyConfigured(
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"Model '%s' has a field named 'timeframed' "
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"which conflicts with the TimeFramedModel manager."
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% sender.__name__
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)
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sender.add_to_class('timeframed', QueryManager(
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(models.Q(start__lte=now) | models.Q(start__isnull=True)) &
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(models.Q(end__gte=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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def _field_exists(model_class, field_name):
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return field_name in [f.attname for f in model_class._meta.local_fields]
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