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Developing
custom
QuerySet
methods
Chibisov
Gennady
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https://github.com/chibisov/events-site-example
!
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Model
methods
1. Instance
methods
2. Class
methods
3. QuerySet
methods
4. Manager
methods
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Instance
methods
class Event(models.Model): !
name = models.CharField(max_length=255)!
slug = models.SlugField(unique=True)!
date_start = models.DateTimeField()!
!
def __unicode__(self):!
return self.name !
!
@property!
def is_published(self):!
# uses current instance data!
return (self.date_start <=!
datetime.datetime.now())!
!
!
>>> yac2012 = Event.objects.get(slug='yac2012')!
>>> yac2012.__unicode__()!
'Yet another Conference 2012'!
>>> yac2012.is_published!
True!
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Class
methods
class Event(models.Model): !
name = models.CharField(max_length=255)!
slug = models.SlugField(unique=True)!
date_start = models.DateTimeField()!
!
@classmethod!
def get_fields_for_csv(cls):!
return ['name', 'slug']!
!
!
>>> Event.get_fields_for_csv()!
['name', 'slug']!
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QuerySet
methods
Event.objects.filter(id__lte=10).delete()!
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QuerySet
methods
Event.objects.all().get_or_create(…)!
Event.objects.all().create(…)!
Event.objects.all().bulk_create(…)
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Manager
methods
class RegionManager(models.Manager):!
def sync_with_geobase(self):!
for region in regions_from_geobase():!
try:!
region_instance = self.model.objects.get(geobase_id=region.id)!
# can modify any instance!
region_instance.name_ru = region.name!
region_instance.name_en = region.ename!
region_instance.save()!
except self.model.DoesNotExist:!
# can create new instances!
region_instance = self.model.objects.create(!
geobase_id=region, !
name_ru=region.name, !
name_en=region.ename!
)!
# can remove instance!
if region.is_deprecated:!
region_instance.delete()!
!
!
>>> Region.objects.sync_with_geobase()!
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Manager
methods
# app/management/commands/sync_with_geobase.py!
class Command(BaseCommand):!
help = u"""Syncs regions with geobase"""!
!
def handle(self, *args, **options):!
Region.objects.sync_with_geobase()!
!
!
$ ./manage.py sync_with_geobase!
!
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This
talk
1. Instance
methods
2. Class
methods
3. QuerySet
methods
4. Manager
methods
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What
for?
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What
for?
1. Readability
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Readability
L
events = Events.objects.all()!
# filter for current site type!
if settings.IS_INTERNAL_SITE:!
events = events.filter(!
Q(is_published_external=True) | !
Q(is_published_internal=True)!
)!
else:!
events = events.filter(!
is_published_for_external=True!
)!
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Readability
J
events = Events.objects.filter_for_current_site_type()!
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Readability
L
yac2012 = Events.objects.get(slug='yac2012')!
!
# is for current site type?!
if settings.IS_INTERNAL_SITE:!
is_for = (yac2012.is_published_for_internal !
and yac2012.is_published_for_external)!
else:!
is_for = yac2012.is_published_for_external!
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Readability
J
yac2012.is_for_current_site_type!
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What
for?
1. Readability
2. Reusability
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Reusability
J
class EventDetailView(DetailView): !
queryset = (Event.objects!
.filter_for_current_site_type())!
!
!
class EventListView(ListView):!
queryset = (Event.objects!
.filter_for_current_site_type())!
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First
manager
# apps/events/managers.py !
from datetime.datetime import now!
from django.db.models.query import QuerySet!
from django.db import models!
!
!
class EventQuerySet(QuerySet):!
def filter_by_published(self):!
return self.filter(date_start__lte=now())!
!
!
class EventManager(models.Manager):!
def get_query_set(self):!
return EventQuerySet(self.model, !
using=self._db)!
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First
manager
# apps/events/models.py!
from django.db import models!
from apps.events.managers import EventManager!
!
!
class Event(models.Model):!
name = models.CharField(max_length=255)!
slug = models.SlugField(unique=True)!
date_start = models.DateTimeField()!
!
objects = EventManager()!
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First
manager
>>> Event.objects.all().filter_by_published()!
!
[, !
]!
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Oops…
>>> Event.objects.filter_by_published()!
!
Traceback (most recent call last):!
File "", line 1, in !
AttributeError: 'EventManager' object has no
attribute 'filter_by_published'!
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Add
proxy
method
class EventManager(models.Manager):!
def get_query_set(self):!
return EventQuerySet(self.model, !
using=self._db)!
!
def filter_by_published(self):!
return (self.get_query_set()!
.filter_by_published())!
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Or
try
to
proxy
all
not
found
class EventManager(models.Manager):!
def get_query_set(self):!
return EventQuerySet(self.model, !
using=self._db)!
!
def __getattr__(self, name):!
if name.startswith('_'):!
raise AttributeError(name)!
else:!
return getattr(self.get_query_set(), !
name)!
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OK
>>> Event.objects.filter_by_published()!
!
[, !
]!
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More
docs.djangoproject.com/en/dev/topics/db/managers/!
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apps.events.models
class EventType(models.Model):!
"""!
Example: Yet Another Conference!
"""!
name = models.CharField(max_length=255)!
slug = models.SlugField(unique=True)!
is_moderated = models.BooleanField(default=False)!
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/events/
• Yet
another
Conference
• I.Subbotnik
• ECIR
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apps.events.models
class Event(models.Model):!
"""!
Example: Yac 2012!
"""!
name = models.CharField(max_length=255)!
slug = models.SlugField(unique=True)!
type = models.ForeignKey(EventType)!
date_start = models.DateTimeField()!
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/events/yac/
• Yac
2010
• Yac
2011
• Yac
2012
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/events/yac/2012/
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/events/
class EventTypeListView(ListView):!
queryset = EventType.objects.all()!
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/events/
• Yet
another
Conference
• I.Subbotnik
• ECIR
(not
moderated)
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EventType
QuerySet
method
class EventTypeQuerySet(QuerySet):!
def filter_by_published(self):!
return self.filter(is_moderated=True)!
!
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/events/
class EventTypeListView(ListView):!
queryset = (EventType.objects!
.filter_by_published())!
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/events/
• Yet
another
Conference
• I.Subbotnik
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/events/yac/
• Yac
2010
• Yac
2011
• Yac
2012
(too
early)
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Event
QuerySet
method
import datetime!
from datetime.datetime import now!
!
class EventQuerySet(QuerySet):!
def filter_by_it_time_to_publish(self):!
d = now() + datetime.timedelta(days=2)!
return self.filter(date_start__lte=d)!
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/events/yac/
class EventTypeDetailView(DetailView):!
queryset = (EventType.objects!
.filter_by_published())!
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/events/yac/
# /templates/events/eventtype_detail.html!
!
{% for e in object.event_set!
.filter_by_it_time_to_publish %}!
{{ e }}
! {% endfor %}!Slide 41
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/events/yac/
• Yac
2010
• Yac
2011
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/events/yac/2012/
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/events/yac/2012/
Show
if
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/events/yac/2012/
Show
if
• It
is
Tme
to
publish
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/events/yac/2012/
Show
if
• It
is
Tme
to
publish
• Yac
EventType
is
published
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/events/yac/2012/
else
404
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/events/yac/2012/
class EventDetailView(DetailView):!
queryset = (Event.objects!
.filter_by_it_time_to_publish())!
!
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/events/yac/2012/
class EventDetailView(DetailView):!
queryset = (Event.objects!
.filter_by_it_time_to_publish())!
!
def get_queryset(self):!
q = super(EventDetailView, !
self).get_queryset()!
return q.filter(type__is_moderated=True)!
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L
EventType.objects.filter_by_published()
not
reused
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/events/yac/2012/
class EventDetailView(DetailView):!
queryset = (Event.objects!
.filter_by_it_time_to_publish())!
!
def get_queryset(self):!
q = super(EventDetailView, !
self).get_queryset()!
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/events/yac/2012/
class EventDetailView(DetailView):!
queryset = (Event.objects!
.filter_by_it_time_to_publish())!
!
def get_queryset(self):!
q = super(EventDetailView, !
self).get_queryset()!
pks = (EventType.objects!
.filter_by_published()!
.values_list('pk', flat=True))!
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/events/yac/2012/
class EventDetailView(DetailView):!
queryset = (Event.objects!
.filter_by_it_time_to_publish())!
!
def get_queryset(self):!
q = super(EventDetailView, !
self).get_queryset()!
pks = (EventType.objects!
.filter_by_published()!
.values_list('pk', flat=True))!
return q.filter(type__pk__in=pks)!
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L
2
DB
queries
Ugly
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/events/yac/2012/
class EventDetailView(DetailView):!
queryset = (Event.objects!
.filter_by_published())!
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Pre\y
1
query
Reuse
filter_by_published
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HOW?
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Q
object
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class EventTypeQuerySet(QuerySet):!
def filter_by_published(self):!
return self.filter(Q(is_moderated=True))!
!
!
class EventQuerySet(QuerySet):!
...!
def filter_by_with_published_type(self):!
return self.filter(Q(type__is_moderated=True))!
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class EventTypeQuerySet(QuerySet):!
def filter_by_published(self):!
return self.filter(Q(is_moderated=True))!
!
!
class EventQuerySet(QuerySet):!
...!
def filter_by_with_published_type(self):!
return self.filter(Q(type__is_moderated=True))!
Diff
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class EventTypeConditions(object):!
@classmethod!
def is_published(cls):!
return Q(is_moderated=True)!
Move
Q
to
funcTon
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class EventTypeConditions(object):!
@classmethod!
def is_published(cls, prefix=None): !
return Q(is_moderated=True)!
Prefix
as
param
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class EventTypeConditions(object):!
@classmethod!
def is_published(cls, prefix=None):!
if prefix:!
field = '%s__is_moderated' % prefix!
else:!
field = 'is_moderated'!
!
return Q(is_moderated=True)!
Field
name
with
prefix
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class EventTypeConditions(object):!
@classmethod!
def is_published(cls, prefix=None):!
if prefix:!
field = '%s__is_moderated' % prefix!
else:!
field = 'is_moderated'!
!
return Q(**{field: True})!
Use
prefixed
field
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>>> EventTypeConditions.is_published()!
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>>> EventTypeConditions.is_published()!
Q(is_moderated=True)!
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>>> EventTypeConditions.is_published()!
Q(is_moderated=True)!
!
>>> EventTypeConditions.is_published(!
... prefix='type'!
... )!
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>>> EventTypeConditions.is_published()!
Q(is_moderated=True)!
!
>>> EventTypeConditions.is_published(!
... prefix='type'!
... )!
Q(type__is_moderated=True)!
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class EventTypeQuerySet(QuerySet):!
def filter_by_published(self):!
return self.filter(!
EventTypeConditions.is_published()!
)!
Use
it
for
EventType
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May
I?
class EventQuerySet(QuerySet):!
...!
def filter_by_with_published_type(self):!
return self.filter(!
EventTypeConditions.is_published(!
prefix='type’!
)!
)!
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NO
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NO
EventTypeCondiTons
is
for
EventType
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NO
EventTypeCondiTons
is
for
EventType
Create
EventCondiTons
for
Event
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class EventConditions(object):!
@classmethod!
def is_with_published_type(cls):!
event_prefix = 'type' !
return EventTypeConditions.is_published(!
prefix=event_prefix!
) !
Create
Event
condiTons
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class EventConditions(object):!
@classmethod!
def is_with_published_type(cls, prefix=None): !
event_prefix = 'type' !
return EventTypeConditions.is_published(!
prefix=event_prefix!
)!
Prefix
as
param
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class EventConditions(object):!
@classmethod!
def is_with_published_type(cls, prefix=None):!
event_prefix = 'type' !
if prefix:!
prefix = '%s__%s' % prefix, event_prefix!
else:!
prefix = event_prefix!
!
return EventTypeConditions.is_published(!
prefix=event_prefix!
)!
Add
prefix
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class EventConditions(object):!
@classmethod!
def is_with_published_type(cls, prefix=None):
event_prefix = 'type'!
if prefix:!
prefix = '%s__%s' % prefix, event_prefix!
else:!
prefix = event_prefix!
!
return EventTypeConditions.is_published(!
prefix=prefix!
)!
Use
prefix
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>>> EventConditions.is_with_published_type()!
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>>> EventConditions.is_with_published_type()!
Q(type__is_moderated=True)!
!
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>>> EventConditions.is_with_published_type()!
Q(type__is_moderated=True)!
!
>>> EventConditions.is_with_published_type(!
... prefix=’event’!
... )!
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>>> EventConditions.is_with_published_type()!
Q(type__is_moderated=True)!
!
>>> EventConditions.is_with_published_type(!
... prefix=’event’!
... )!
Q(event__type__is_moderated=True)!
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Use
it
for
Event
class EventQuerySet(QuerySet):!
...!
def filter_by_with_published_type(self):!
return self.filter(!
EventConditions.is_with_published_type()!
)!
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Lets
refactor
class EventQuerySet(QuerySet):!
...!
def filter_by_it_time_to_publish(self):!
d = now() + datetime.timedelta(days=2)!
return self.filter(date_start__lte=d)!
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class EventConditions(object):!
@classmethod!
def is_with_published_type(cls, prefix=None):!
...!
!
@classmethod!
def is_it_time_to_publish(cls, prefix=None): !
if prefix:!
field = '%s__date_start__lte' % prefix!
else:!
field = 'date_start__lte'!
!
d = now() + datetime.timedelta(days=2) !
return Q(**{field: d})!
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Aaer
refactor
class EventQuerySet(QuerySet):!
...!
def filter_by_it_time_to_publish(self):!
return self.filter(!
EventConditions.is_it_time_to_publish()!
)!
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Combining
methods
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class EventConditions(object):!
@classmethod!
def is_with_published_type(cls, prefix=None):!
...!
!
@classmethod!
def is_it_time_to_publish(cls, prefix=None): !
...!
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class EventConditions(object):!
@classmethod!
def is_with_published_type(cls, prefix=None):!
...!
!
@classmethod!
def is_it_time_to_publish(cls, prefix=None): !
...!
!
@classmethod!
def is_published(cls, prefix=None):!
return (!
cls.is_with_published_type(prefix) & !
cls.is_it_time_to_publish(prefix)!
)!
!
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>>> EventConditions.is_published()!
!
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>>> EventConditions.is_published()!
Q(date_start__lte=datetime(23,11,2012)) &!
Q(type__is_moderated=True)!
!
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>>> EventConditions.is_published()!
Q(date_start__lte=datetime(23,11,2012)) &!
Q(type__is_moderated=True)!
!
>>> EventConditions.is_published(!
... prefix=’event’!
... )!
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>>> EventConditions.is_published()!
Q(date_start__lte=datetime(23,11,2012)) &!
Q(type__is_moderated=True)!
!
>>> EventConditions.is_published(!
... prefix=’event’!
... )!
Q(event__date_start__lte=datetime(23,11,2012))&!
Q(event__type__is_moderated=True)!
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Model
instance
methods
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How
to
reuse
condiTons?
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How
to
reuse
condiTons?
class
Event(models.Model):
...
@property
def
is_with_published_type(self):
return
EventConditions.is_with_published_type(model_instance=self)
@property
def
is_it_time_to_publish(self):
return
EventConditions.is_it_time_to_publish(model_instance=self)
@property
def
is_published(self):
return
EventConditions.is_published(model_instance=self)!
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True
and
False
=
True
&
False
How
to
reuse
condiTons?
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True
or
False
=
True
|
False
How
to
reuse
condiTons?
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More
https://github.com/chibisov/events-site-example
!
/apps/accounts/models.py
/apps/accounts/managers.py
/apps/events/models.py
/apps/events/managers.py
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How
to
test
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Use
makers
• make_published
• make_not_published
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Use
makers
class TestEventIsPublished(TestConditionBase):!
def test_1(self):!
makers.event.make_with_published_type(self.instance)!
makers.event.make_it_time_to_publish(self.instance)!
!
self.assertConditionTrue(msg=msg)!
!
def test_2(self):!
makers.event.make_with_published_type(self.instance)!
makers.event.make_not_it_time_to_publish(self.instance)!
!
self.assertConditionFalse(msg=msg)!
!
def test_3(self):!
makers.event.make_it_time_to_publish(self.instance)!
makers.event.make_not_with_published_type(self.instance)!
!
self.assertConditionFalse(msg=msg)!
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More
https://github.com/chibisov/events-site-example
!
/apps/accounts/makers/
/apps/accounts/tests/condiTons/
/apps/events/makers/
/apps/events/tests/condiTons/
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class DistributionSendedConditions(object):!
@classmethod!
def is_ready_to_start_with_in_progress_status(cls, prefix=None):!
k = {!
'prefix': prefix!
}!
!
return (!
(cls.is_with_status(status='in_progress', **k)) &!
((cls.is_last_message_sended_more_than_5_minutes_ago(**k)) |!
(cls.is_not_has_messages(**k) & !
cls.is_started_sending_more_than_5_minutes_ago(**k)))!
)!
More
complex
condiTons
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Спасибо