Question

There seem to be quite a few issues related to circular import errors just with models, but I seem to be getting a similar problem with my model and signal callbacks. I’m fairly new to Django, so in all likelihood it’s more to do with me not structuring my app correctly. Some code:

badges/models.py:

from django.db import models
from django.contrib.auth.models import User
from datetime import datetime
from tasks import badgeaward_callback

class Award(models.Model):
    user = models.ForeignKey(User)
    description = models.TextField(blank=False)
    award_date = models.DateTimeField('date awarded',default=datetime.now)

    def __unicode__(self):
        return self.description

class Points(models.Model):
    POINT_TYPES = (
        ('signup', 'Sign up'),
        ...etc...
    )
    user = models.ForeignKey(User)
    points = models.IntegerField()
    date = models.DateTimeField('date created',default=datetime.now)
    description = models.TextField(blank=False)
    data = models.TextField(blank=True)
    type = models.CharField(max_length=20,choices=POINT_TYPES)

    def __unicode__(self):
        return self.description

models.signals.post_save.connect(badgeaward_callback, sender=Award)

badges/tasks.py

from badges.models import Points

def badgeaward_callback(sender, **kwargs):
    award = kwargs.get('award')

    p = Points()
    p.points = 100
    p.type = 'badgeawarded'
    p.description = award.description
    p.user = award.user
    p.save()

So, models is importing badgeaward_callback (this is the error I get: cannot import name badgeaward_callback), but tasks is importing Points model – I assume this is the root cause of my error.

Any advice on how I should be structuring my app is much appreciated. Should I just put my badgesaward_callback into models.py? That works (well, no more error), but is it a good approach when later I may be adding quite a few more callback functions?

Answer 1

In terms of better structure, instead of tasks.py rename it signals.py and from models.py

models.signals.post_save.connect(badgeaward_callback, sender=Award)

move this line to signals.py at end. Then you don’t require the import from tasks import badgeaward_callback in models.py