mirror of
https://github.com/Hopiu/django-imagekit.git
synced 2026-03-17 05:40:25 +00:00
123 lines
4.6 KiB
Python
123 lines
4.6 KiB
Python
from django.db.models.signals import post_init, post_save, post_delete
|
|
from django.utils.functional import wraps
|
|
from ..signals import source_created, source_changed, source_deleted
|
|
|
|
|
|
def ik_model_receiver(fn):
|
|
"""
|
|
A method decorator that filters out signals coming from models that don't
|
|
have fields that function as ImageFieldSpecSources
|
|
|
|
"""
|
|
@wraps(fn)
|
|
def receiver(self, sender, **kwargs):
|
|
if sender in (src.model_class for src in self._sources):
|
|
fn(self, sender=sender, **kwargs)
|
|
return receiver
|
|
|
|
|
|
class ModelSignalRouter(object):
|
|
"""
|
|
Handles signals dispatched by models and relays them to the spec sources
|
|
that represent those models.
|
|
|
|
"""
|
|
|
|
def __init__(self):
|
|
self._sources = []
|
|
uid = 'ik_spec_field_receivers'
|
|
post_init.connect(self.post_init_receiver, dispatch_uid=uid)
|
|
post_save.connect(self.post_save_receiver, dispatch_uid=uid)
|
|
post_delete.connect(self.post_delete_receiver, dispatch_uid=uid)
|
|
|
|
def add(self, source):
|
|
self._sources.append(source)
|
|
|
|
def init_instance(self, instance):
|
|
instance._ik = getattr(instance, '_ik', {})
|
|
|
|
def update_source_hashes(self, instance):
|
|
"""
|
|
Stores hashes of the source image files so that they can be compared
|
|
later to see whether the source image has changed (and therefore whether
|
|
the spec file needs to be regenerated).
|
|
|
|
"""
|
|
self.init_instance(instance)
|
|
instance._ik['source_hashes'] = dict((attname, hash(file_field))
|
|
for attname, file_field in self.get_field_dict(instance).items())
|
|
return instance._ik['source_hashes']
|
|
|
|
def get_field_dict(self, instance):
|
|
"""
|
|
Returns the source fields for the given instance, in a dictionary whose
|
|
keys are the field names and values are the fields themselves.
|
|
|
|
"""
|
|
return dict((src.image_field, getattr(instance, src.image_field)) for
|
|
src in self._sources if src.model_class is instance.__class__)
|
|
|
|
@ik_model_receiver
|
|
def post_save_receiver(self, sender, instance=None, created=False, raw=False, **kwargs):
|
|
if not raw:
|
|
self.init_instance(instance)
|
|
old_hashes = instance._ik.get('source_hashes', {}).copy()
|
|
new_hashes = self.update_source_hashes(instance)
|
|
for attname, file in self.get_field_dict(instance).items():
|
|
if created:
|
|
self.dispatch_signal(source_created, file, sender, instance,
|
|
attname)
|
|
elif old_hashes[attname] != new_hashes[attname]:
|
|
self.dispatch_signal(source_changed, file, sender, instance,
|
|
attname)
|
|
|
|
@ik_model_receiver
|
|
def post_delete_receiver(self, sender, instance=None, **kwargs):
|
|
for attname, file in self.get_field_dict(instance).items():
|
|
self.dispatch_signal(source_deleted, file, sender, instance, attname)
|
|
|
|
@ik_model_receiver
|
|
def post_init_receiver(self, sender, instance=None, **kwargs):
|
|
self.update_source_hashes(instance)
|
|
|
|
def dispatch_signal(self, signal, file, model_class, instance, attname):
|
|
"""
|
|
Dispatch the signal for each of the matching sources. Note that more
|
|
than one source can have the same model and image_field; it's important
|
|
that we dispatch the signal for each.
|
|
|
|
"""
|
|
for source in self._sources:
|
|
if source.model_class is model_class and source.image_field == attname:
|
|
info = dict(
|
|
source=source,
|
|
instance=instance,
|
|
field_name=attname,
|
|
)
|
|
signal.send(sender=source, source_file=file, info=info)
|
|
|
|
|
|
class ImageFieldSpecSource(object):
|
|
def __init__(self, model_class, image_field):
|
|
"""
|
|
Good design would dictate that this instance would be responsible for
|
|
watching for changes for the provided field. However, due to a bug in
|
|
Django, we can't do that without leaving abstract base models (which
|
|
don't trigger signals) in the lurch. So instead, we do all signal
|
|
handling through the signal router.
|
|
|
|
Related:
|
|
https://github.com/jdriscoll/django-imagekit/issues/126
|
|
https://code.djangoproject.com/ticket/9318
|
|
|
|
"""
|
|
self.model_class = model_class
|
|
self.image_field = image_field
|
|
signal_router.add(self)
|
|
|
|
def files(self):
|
|
for instance in self.model_class.objects.all():
|
|
yield getattr(instance, self.image_field)
|
|
|
|
|
|
signal_router = ModelSignalRouter()
|