Modelos Many to Many

models.py

class Banner(AuditableModel):
    image = models.ImageField(verbose_name="Archivo", upload_to="banner/original")
    position = models.IntegerField("Orden", default=0) 
    name = models.CharField("Nombre", max_length=120, blank=True) 
    url = models.CharField("Enlace", max_length=220, blank=True)
    
    def url_normal(self):
        url  = "{0}/banner/normal/{1}".format(settings.MEDIA_URL, self.image)
        return url
    
    class Meta:
        """ ."""
        verbose_name = u'Banner'
        verbose_name_plural = u'Banners'
        ordering = ['position']

class Seccion(AuditableModel):
    name = models.CharField("Nombre", max_length=120)
    nick = models.CharField("Identificador", max_length=120)
    url = models.CharField("Enlace", max_length=220, blank=True)
    descrip = models.TextField("Descripción", blank=True)
    position = models.IntegerField("Orden", default=0)
    banner = models.ManyToManyField(Banner, verbose_name=u"Banners",through='SeccionBanner' ) 
    
    parent_category = models.ForeignKey("self", 
                                        verbose_name=u"Seccion superior",
                                        blank=True,
                                        null=True) 
    
    class Meta:
        """ ."""
        verbose_name = u'Seccion'
        verbose_name_plural = u'Secciones'
        ordering = ['position'] 
        
    def __unicode__(self): 
        # print self
        # full = ' %s' % ( self.name )self.parent_category.name if self.parent_category.name else ''
        full = ' %s' % ( self.name )
        return full