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netbox-community-netbox/netbox/netbox/denormalized.py
2022-11-02 15:25:22 -04:00

59 lines
2.0 KiB
Python

import logging
from django.db.models.signals import post_save
from django.dispatch import receiver
from netbox.registry import registry
logger = logging.getLogger('netbox.denormalized')
def register(model, field_name, mappings):
"""
Register a denormalized model field to ensure that it is kept up-to-date with the related object.
Args:
model: The class being updated
field_name: The name of the field related to the triggering instance
mappings: Dictionary mapping of local to remote fields
"""
logger.debug(f'Registering denormalized field {model}.{field_name}')
field = model._meta.get_field(field_name)
rel_model = field.related_model
registry['denormalized_fields'][rel_model].append(
(model, field_name, mappings)
)
@receiver(post_save)
def update_denormalized_fields(sender, instance, created, raw, **kwargs):
"""
Check if the sender has denormalized fields registered, and update them as necessary.
"""
def _get_field_value(instance, field_name):
field = instance._meta.get_field(field_name)
return field.value_from_object(instance)
# Skip for new objects or those being populated from raw data
if created or raw:
return
# Look up any denormalized fields referencing this model from the application registry
for model, field_name, mappings in registry['denormalized_fields'].get(sender, []):
logger.debug(f'Updating denormalized values for {model}.{field_name}')
filter_params = {
field_name: instance.pk,
}
update_params = {
# Map the denormalized field names to the instance's values
denorm: _get_field_value(instance, origin) for denorm, origin in mappings.items()
}
# TODO: Improve efficiency here by placing conditions on the query?
# Update all the denormalized fields with the triggering object's new values
count = model.objects.filter(**filter_params).update(**update_params)
logger.debug(f'Updated {count} rows')