Following the docs found here but I'm not receiving the signal. Is there more to add?
community/signals.py
from wagtail.core.signals import page_published
from wagtailPages.models import CommunityArticle
from notification.models import Notification
def notify_article_author(sender, **kwargs):
print("Processing page_published signal")
...
page_published.connect(notify_article_author, sender=CommunityArticle)
You need to make sure that the code is actually being loaded and run - usually this is done by registering the signal within the ready method of your AppConfig. (If you haven't already, you'll need to define default_app_config in __init__.py, as detailed at https://docs.djangoproject.com/en/stable/ref/applications/#for-application-authors .)
Related
In the docs for Django's System check framework it says:
Checks should be registered in a file that’s loaded when your application is loaded; for example, in the AppConfig.ready() method.
None of the examples on that page, or around the AppConfig.ready() method, show how to do this. Given a checking method like:
from django.core.checks import register, Tags
#register(Tags.compatibility)
def my_check(app_configs, **kwargs):
# ... perform compatibility checks and collect errors
return errors
How would you do this in/from the AppConfig.ready() method? Is one called from the other? Which file should the above method go in? Do you add #register(...) to the ready() method?
From reading the examples on this page about the Apps Registry and System Checks Framework, it seems there are (at least) two ways to add your own System Checks. To adapt that page's examples (assuming you're creating an app called myapp):
1) Create a myapp/checks.py file like this:
from django.apps import apps as camelot_apps
from django.core.checks import register, Warning
from django.core.checks import Tags as DjangoTags
class Tags(DjangoTags):
"""Do this if none of the existing tags work for you:
https://docs.djangoproject.com/en/1.8/ref/checks/#builtin-tags
"""
my_new_tag = 'my_new_tag'
#register(Tags.my_new_tag)
def check_taggit_is_installed(app_configs=None, **kwargs):
"Check that django-taggit is installed when usying myapp."
errors = []
try:
from taggit import models
except ImportError:
errors.append(
Warning(
"The django-taggit app is required to use myapp.",
hint=("Install django-taggit"),
# A unique ID so it's easier to find this warning:
id='myapp.W001',
)
)
return errors
And then in myapp/__init__.py (create it if it doesn't exist):
from . import checks
Running this should run that check above:
$ ./manage.py check myapp
2) Or, as I thought in my initial question, you can register that check in your AppConfig. So, keep the above code in myapp/check.py, but remove the #register(Tags.my_new_tag) line.
Then create myapp/apps.py containing this:
from django.core.checks import register
from .checks import Tags, check_taggit_is_installed
class MyappConfig(AppConfig):
name = 'myapp'
def ready(self):
super(MyappConfig, self).ready()
register(Tags.my_new_tag)(check_taggit_is_installed)
And alter myapps/__init__.py so it contains this:
from . import checks
default_app_config = 'myapp.apps.MyappConfig'
The first example seems simpler, with no need for a custom AppConfig.
Django recommends:
Checks should be registered in a file that’s loaded when your application is loaded; for example, in the AppConfig.ready() method.
Therefore, place the checks code in a checks.py file. Then simply in apps.py, as with signals:
from django.apps import AppConfig
class MyAppConfig(AppConfig):
name = 'MyApp'
verbose_name = "My App"
def ready(self):
# import myapp.signals
import myapp.checks
My guess is that you can just place this code in ready() method. For example of usage you can take a look at django.contrib.auth (or other contrib app). This app has check in checks.py file, that imported in apps.py and registered in ready() method: checks.py, apps.py.
I am trying to leverage the post_save function of Django Signals in combination with Celery tasks. After a new Message object is saved to the database, I want to evaluate if the instance has one of two attributes and if it does, call the 'send_sms_function' which is a Celery registered task.
tasks.py
from my_project.celery import app
#app.task
def send_sms_message(message):
# Do something
signals.py
from django.db.models.signals import post_save
from django.dispatch import receiver
import rollbar
rollbar.init('234...0932', 'production')
from dispatch.models import Message
from comm.tasks import send_sms_message
#receiver(post_save, sender=Message)
def send_outgoing_messages(sender, instance, **kwargs):
if instance.some_attribute == 'A' or instance.some_attribute == 'B':
try:
send_sms_message.delay(instance)
except:
rollbar.report_exc_info()
else:
pass
I'm testing this locally by running a Celery worker. When I am in the Django shell and call the Celery function, it works as expected. However when I save a Message instance to the database, the function does not work as expected: There is nothing posted to the task queue and I do not see any error messages.
What am I doing wrong?
This looks like a problem with serializing and/or your settings. When celery passes the message to your broker, it needs to have some representation of the data. Celery serializes the arguments you give a task but if you don't have it configured consistently with what you're passing (i.e. you have a mismatch where your broker is expecting JSON but you send it a pickled python object), tasks can fail simply because the worker can't easily decode what you're sending it. If you run the function in your shell (without the call to delay) it is called synchronously so there is no serialization or message passing.
In your settings you should be using the JSON serialization (unless you have a really good reason) but if not, then there could be something wrong with your pickling. You can always increase the log level to debug when you run celery to see more about serialization related errors with:
celery -A yourapp worker -l debug
When in doubt, use that print statement/function to make sure your signal receiver is running. If not, you can create an AppConfig class that imports your receivers in it's ready method or some other reasonable technique for making sure your receivers are being registered.
[opinion]
I would suggest doing something like this:
#receiver(post_save, sender=Message)
def send_outgoing_messages(sender, instance, **kwargs):
enqueue_message.delay(instance.id)
in yourmodule/tasks.py
#app.task
def enqueue_message(message_id):
msg = Message.object.get(id=message_id)
if msg.some_attribute in ('A', 'B'): # slick or
send_sms_message.delay(message_id)
You can always use Celery's composition techniques but here you have something that doesn't add more complexity to your request/response cycle.
[/opinion]
The expression if instance.some_attribute == 'A' or 'B' is probably your problem.
What you probably mean is:
if instance.some_attribute == 'A' or instance.some_attribute == 'B'
Or, how I would write it:
if instance.some_attribute in ('A', 'B')
you are calling the function synchronously instead of queuing it:
send_sms_message.delay(instance)
should queue the message
http://celery.readthedocs.org/en/latest/reference/celery.app.task.html#celery.app.task.Task.delay
http://celery.readthedocs.org/en/latest/userguide/calling.html#basics
#dgel also points out a logic error
I realize there are many other questions related to custom django signals that don't work, and believe me, I have read all of them several times with no luck for getting my personal situation to work.
Here's the deal: I'm using django-rq to manage a lengthy background process that is set off by a particular http request. When that background process is done, I want it to fire off a custom Django signal so that the django-rq can be checked for any job failure/exceptions.
Two applications, both on the INSTALLED_APPS list, are at the same level. Inside of app1 there is a file:
signals.py
import django.dispatch
file_added = django.dispatch.Signal(providing_args=["issueKey", "file"])
fm_job_done = django.dispatch.Signal(providing_args=["jobId"])
and also a file jobs.py
from app1 import signals
from django.conf import settings
jobId = 23
issueKey = "fake"
fileObj = "alsoFake"
try:
pass
finally:
signals.file_added.send(sender=settings.SIGNAL_SENDER,issueKey=issueKey,fileName=fileObj)
signals.fm_job_done.send(sender=settings.SIGNAL_SENDER,jobId=jobId)
then inside of app2, in views.py
from app1.signals import file_added, fm_job_done
from django.conf import settings
#Setup signal handlers
def fm_job_done_callback(sender, **kwargs):
print "hellooooooooooooooooooooooooooooooooooo"
logging.info("file manager job done signal fired")
def file_added_callback(sender, **kwargs):
print "hellooooooooooooooooooooooooooooooooooo"
logging.info("file added signal fired")
file_added.connect(file_added_callback,sender=settings.SIGNAL_SENDER,weak=False)
fm_job_done.connect(fm_job_done_callback,sender=settings.SIGNAL_SENDER,weak=False)
I don't get any feedback whatsoever though and am at a total loss. I know for fact that jobs.py is executing, and therefore also that the block of code that should be firing the signals is executing as well since it is in a finally block (no the try is not actually empty - I just put pass there for simplicity) Please feel free to ask for more information - I'll respond asap.
here is the solution for django > 2.0
settings.py:
change name of your INSTALLED_APPS from 'app2' to
'app2.apps.App2Config'
app2 -> apps.py:
from app1.signals import file_added, fm_job_done
Class App2Config(AppConfig):
name = 'app2'
def ready(self):
from .views import fm_job_done_callback, file_added_callback
file_added.connect(file_added_callback)
fm_job_done.connect(fm_job_done_callback)
use django receiver decorator
from django.dispatch import receiver
from app1.signals import file_added, fm_job_done
#receiver(fm_job_done)
def fm_job_done_callback(sender, **kwargs):
print "helloooooooooooooo"
#receiver(file_added)
def file_added_callback(sender, **kwargs):
print "helloooooooooooooo"
Also, I prefer to handle signals in models.py
I have the requirement that whenever there is a model get's added/changed/deleted, it should send a mail notification. The content will be more like the django_admin_log entries. I just need to extend this functionality in my model to send the mail. Any suggestions?
Django_log_admin will only track changes made in the admin interface. If the model is changed anywhere else, it will not update the log. However, if you are OK with just admin changes, then you can use a combination of django_log_admin and the post_save signal to do the trick. Put this in your management.py:
from django.db.models.signals import post_save
from django.dispatch import receiver
from django.contrib.admin.models import LogEntry
from django.core.mail import mail_admins
from django.template.loader import render_to_string
#will be triggered every time a LogEntry is saved i.e. every time an action is made.
#receiver(post_save, sender=LogEntry)
def send_notification_email(change, **kwargs):
mail_admins(subject="model %(model) has been changed by %(user)" %
{'model':change.content_type, 'user': change.user},
message = render_to_string('change_email.html', { 'change': change }) )
note to self: wow, django really includes all the batteries :D
You should look at Django's signals. In your case, you'll connect your handlers to the post_save and post_delete signals, for starters. Look through the built-in signal documentation for others you may want to tap. No need to hack into admin.
I've been struggling with this problem for 5 hours and I have a feeling it's a simple solution that I'm just overlooking.
I'm trying to tie in a third party module (Django Activity Stream) that uses a series of senders and receivers to post data about user activity to a database table. Everything is set up and installed correctly, but I get a 'Signal' Object has No Attribute 'Save' error when I try to run it.
I suspect the problem is in my syntax somewhere. I'm just getting started with Signals, so am probably overlooking something a veteran will spot immediately.
In views.py I have:
from django.db.models.signals import pre_save
from actstream import action ##This is the third-party app
from models import Bird
def my_handler(sender, **kwargs):
action.save(sender, verb='was saved')
#return HttpResponse("Working Great")
pre_save.connect(my_handler, sender=Bird)
def animal(request):
animal = Bird()
animal.name = "Douglas"
animal.save()
The Django Activity Stream app has this signals.py file:
from django.dispatch import Signal
action = Signal(providing_args=['actor','verb','target','description','timestamp'])
And then this models.py file:
from datetime import datetime
from operator import or_
from django.db import models
from django.db.models.query import QuerySet
from django.core.urlresolvers import reverse
from django.utils.translation import ugettext_lazy as _
from django.utils.timesince import timesince as timesince_
from django.contrib.contenttypes import generic
from django.contrib.contenttypes.models import ContentType
from django.contrib.auth.models import User
from actstream import action
...
def action_handler(verb, target=None, **kwargs):
actor = kwargs.pop('sender')
kwargs.pop('signal', None)
action = Action(actor_content_type=ContentType.objects.get_for_model(actor),
actor_object_id=actor.pk,
verb=unicode(verb),
public=bool(kwargs.pop('public', True)),
description=kwargs.pop('description', None),
timestamp=kwargs.pop('timestamp', datetime.now()))
if target:
action.target_object_id=target.pk
action.target_content_type=ContentType.objects.get_for_model(target)
action.save()
action.connect(action_handler, dispatch_uid="actstream.models")
Your main problem is in the discipline in maintaining coding style, or rather in this case, lack of. You will find that it is easier to identify problems in your code if you do not use the same name to refer to multiple things within the same module; give each object a unique, meaningful name, and refer to it using only that name.
The bottom line here is that the docs for that project contain bad code. This line:
action.save(sender, verb='was saved')
isn't ever going to work. The from actstream import action ultimately imports a signal from actstream.signals, and signals do not and never have had a save method. Especially not with such an odd signature of sender, verb.
At first I thought maybe the author had done something odd with subclassing Signal, but after looking at the rest of the codebase, that's just not the case. I'm not entirely sure what the intention of those docs was supposed to be, but the right thing to do in your handler will either be to save a new Action (imported from actstream.models) instance, or to do something with your model.
Sadly, the project's repository has a pretty sorry set of tests/examples, so without downloading and trying the app myself, I can't tell you what needs to happen there. You might try contacting the author or simply try finding a better-documented/better-maintained Activity Streams app.