Register m2m changed event.

models.py

# Voir https://docs.djangoproject.com/fr/3.0/ref/signals/#m2m-changed pour plus d'infos

@receiver(m2m_changed, sender = VisiteMedicale.animaux.through)
def visite_medicale_save_action(sender, instance, **kwargs):
    if reverse:
        # Cas de popi.visite_medicale_set.remove(sterilisation_20200413)
        animaux = [instance]
        visite_medicale = model.objects.get(pk__in=pk_set)
    else:
        # Cas de sterilisation_20200413.animaux.add(Popi)
        animaux = model.objects.filter(pk__in=pk_set).all()
        visite_medicale = instance
        
    type_visite = visite_medicale.type_visite
    print("Type visite : " + type_visite + "\n")
    sys.stdout.flush()
    if type_visite in (TypeVisiteVetoChoice.STE.name, TypeVisiteVetoChoice.VAC.name):
        sys.stdout.flush()
        for animal in animaux:
            print("Animal : " + animal.nom + "\n")
            sys.stdout.flush()
            if type_visite == TypeVisiteVetoChoice.STE.name:
                animal.sterilise = OuiNonChoice.OUI.name
            elif instance.type_visite == TypeVisiteVetoChoice.VAC.name:
                animal.vaccine = OuiNonChoice.OUI.name
                animal.date_dernier_vaccin = instance.date
            animal.save()