forms.py

class BandGenreForm(ModelForm):
	class Meta:
		model = BandGenre
		fields = ('genre',)

model.py

class Genre(models.Model):  
    name = models.CharField(max_length=765)
    class Meta:
        db_table = u'genre'

    def __unicode__(self):
        return u'%s' % (self.name)

class BandGenre(models.Model):
    band = models.ForeignKey(Band, unique=True)
    genre = models.ManyToManyField(Genre)
    created = models.DateTimeField(auto_now_add=True, null=True, blank=True)
    edited = models.DateTimeField(auto_now=True, null=True, blank=True)
    class Meta:
        db_table = u'band_genre'

    def __unicode__(self):
        return u'%s <-> %s' % (self.band, self.genre)

view.py

def EditBandDetail(request, band_id, template='band_detail.html'):
    try:
        band = get_object_or_404(Band, pk=band_id)
        genre = get_object_or_404(BandGenre, pk=band_id)
    except Band.DoesNotExist:
        raise Http404(u'Not found')

    genre_form = BandGenreForm()

    if request.POST:
        genre_form = BandGenreForm(request.POST, initial=genre)
        if genre_form.is_valid():
            genre_form.save()
            return HttpResponseRedirect('/lookup/')
        else:
            genre_form = BandGenreForm()

    context = Context({
        'band': band,
        'genre': genre,
        'genre_form': genre_form,
    })
    
    return render(request, template, context)