Assume I have this model :
class Task(models.Model):
title = models.CharField()
Now I would like that a task may be relates to another
Yea you can do that, make the ForeignKey attribute a string:
class Task(models.Model):
title = models.CharField()
relates_to = ForeignKey(to='Task')
In depth, you can also cross reference an app's model by using the dot notation, e.g.
class Task(models.Model):
title = models.CharField()
relates_to = ForeignKey(to='.Task') # e.g. 'auth.User'