Django post_syncdb signal handler not getting called?

Question

I have a myapp/management/__init__.py that is registering a post_syncdb handler like so:

from django.db.models import signals
from features import models as features

def create_features(app, created_models, verbosity, **kwargs):
    print "Creating features!"
    # Do stuff...

signals.post_syncdb.connect(create_features, sender=features)

I've verified the following:

Both features and myapp are in settings.INSTALLED_APPS
myapp.management is getting loaded prior to the syncdb running (verified via a print statement at the module level)
The features app is getting processed by syncdb, and it is emitting a post_syncdb signal (verified by examining syncdb's output with --verbosity=2.
I'm using the exact same idiom for another pair of apps, and that handler is called correctly. I've compared the two modules and found no relevant differences between the invocations.

However, myapp.management.create_features is never called. What am I missing?

This question is from 2010. See here for a solution valid in year 2016: http://stackoverflow.com/a/32446857/633961 — guettli, Oct 19 '16 at 09:57

score 3 · Accepted Answer · answered Dec 09 '10 at 00:49

3

try putting it in your models.py

answered Dec 09 '10 at 00:49

Paulo

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2

This will technically work, I suppose, so I'll accept it as an answer, but this really belongs somewhere in the management hierarchy, as per the documentation: http://docs.djangoproject.com/en/dev/ref/signals/#post-syncdb – David Eyk Jan 15 '11 at 16:41
This answer is from 2010. See here for a solution valid in year 2016: http://stackoverflow.com/a/32446857/633961 – guettli Oct 19 '16 at 09:58

score 1 · Answer 2 · answered Nov 10 '11 at 11:24

Just came across the same issue, and the way I solved it was to remove the sender from function arguments and check for it inside the callback function.

from django.db.models import signals
from features import models as features

def create_features(app, created_models, verbosity, **kwargs):
    print "Creating features!"
    if app != features #this will work as it compares models module instances
        return
    # Do stuff...

signals.post_syncdb.connect(create_features)

That way you can keep them in your management module like Django docs suggest. I agree that it should work like you suggested. You could probably dig into the implementation of the Signal class in django.dispatch.

score 0 · Answer 3 · edited Jun 20 '20 at 09:12

The point is in the sender. Your custom callback is called only if sender worked out. In my case the sender was db.models and it is not worked out if syncdb called not the first time, i.o. the synced models are exist in database. In the documents it is written, but do not putted a proper emphasis.

sender

The models module that was just installed. That is, if syncdb just installed an app called "foo.bar.myapp", sender will be the foo.bar.myapp.models module.

So my solution was drop the database and install my app again.

Django post_syncdb signal handler not getting called?

3 Answers3