from django.db.models.signals import pre_save
from django.dispatch import receiver
from .models import Farmer

@receiver(pre_save, sender=Farmer)
def auto_increment_tripoli_farmer_id(sender, instance, **kwargs):
    if instance.tripoli_farmer_id is None:  # Перевірка, чи поле не заповнене
        last_farmer = Farmer.objects.order_by('-tripoli_farmer_id').first()
        if last_farmer:
            instance.tripoli_farmer_id = last_farmer.tripoli_farmer_id + 1
        else:
            instance.tripoli_farmer_id = 1  # Починаємо з 1, якщо записів немає