thrillwiki_django_no_react/companies/signals.py

from django.db.models.signals import post_save, post_delete
from django.dispatch import receiver
from django.db.utils import ProgrammingError
from parks.models import Park
from rides.models import Ride
from .models import Company, Manufacturer

@receiver([post_save, post_delete], sender=Park)
def update_company_stats(sender, instance, **kwargs):
    """Update company statistics when a park is added, modified, or deleted."""
    if instance.owner:
        try:
            # Update total parks
            total_parks = Park.objects.filter(owner=instance.owner).count()
            total_rides = Ride.objects.filter(park__owner=instance.owner).count()
            
            Company.objects.filter(id=instance.owner.id).update(
                total_parks=total_parks,
                total_rides=total_rides
            )
        except ProgrammingError:
            # If rides table doesn't exist yet, just update parks count
            total_parks = Park.objects.filter(owner=instance.owner).count()
            Company.objects.filter(id=instance.owner.id).update(
                total_parks=total_parks
            )

@receiver([post_save, post_delete], sender=Ride)
def update_manufacturer_stats(sender, instance, **kwargs):
    """Update manufacturer statistics when a ride is added, modified, or deleted."""
    if instance.manufacturer:
        try:
            # Update total rides and roller coasters
            total_rides = Ride.objects.filter(manufacturer=instance.manufacturer).count()
            total_roller_coasters = Ride.objects.filter(
                manufacturer=instance.manufacturer,
                category='RC'
            ).count()
            
            Manufacturer.objects.filter(id=instance.manufacturer.id).update(
                total_rides=total_rides,
                total_roller_coasters=total_roller_coasters
            )
        except ProgrammingError:
            pass  # Skip if rides table doesn't exist yet

@receiver(post_save, sender=Ride)
def update_company_ride_stats(sender, instance, **kwargs):
    """Update company ride statistics when a ride is added or modified."""
    if instance.park and instance.park.owner:
        try:
            total_rides = Ride.objects.filter(park__owner=instance.park.owner).count()
            Company.objects.filter(id=instance.park.owner.id).update(total_rides=total_rides)
        except ProgrammingError:
            pass  # Skip if rides table doesn't exist yet