Create activity optionally based on instance attribute values

[umair-tp]

I have a model as following:

class UserMoodLog(TimeStampedModel, Activity):
    user = models.ForeignKey('users.User', on_delete=models.CASCADE)
    is_happy = models.BooleanField(_("is happy"), default=False)

I want to create activity associated to this model on it's creation only when is_happy=True. I tried overriding create_activity() and call super create_activity() only when is_happy=True but a activity must be returned from that, otherwise this line

stream-django/stream_django/managers.py

Line 64 in 9f5fcce

result = feed.add_activity(activity)

will throw error, as activity is None (because when is_happy=False I am not calling super create_activity() and thus None is returned by overridden create_activity())

Can someone please point me towards the right direction ?