I have a category kind of model (called Tag):
class Tag(models.Model):
    name = models.CharField(...)
    slug = models.SlugField(unique=True)
    #...
Used as m2m field in another model:
class Order(models.Model):
    user = models.ForeignKey(...)
    type = models.CharField(...)
    tag = models.ManyToManyField(Tag, blank=True)
Now, suppose an order is created and program wants to assign some tags to it automatically. Say, program wants to add Order.type to itsOrder.tag list. (Suppose Order.type happens to be same as a valid Tag.name)
I tried Order's post_save to no luck:
def order_post_save_reciever(sender, instance, *args, **kwargs):
    #..., disconnect, ...
    instance.tag.add(Tag.objects.filter(name=instance.type))
    instance.save()
    #.... reconnec, t.....
Apparently, I have to use signals, but I don't know how. Do you know how to add a tag here? Your help is much appreciated.
 
    