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Arthur Hanson 149a496011 6347 Cache the number of each component type assigned to devices/VMs (#12632)
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Co-authored-by: Jeremy Stretch <jstretch@netboxlabs.com>
2023-07-25 09:39:05 -04:00

53 lines
1.9 KiB
Python

from collections import defaultdict
from django.core.management.base import BaseCommand
from django.db.models import Count, OuterRef, Subquery
from netbox.registry import registry
class Command(BaseCommand):
help = "Force a recalculation of all cached counter fields"
@staticmethod
def collect_models():
"""
Query the registry to find all models which have one or more counter fields. Return a mapping of counter fields
to related query names for each model.
"""
models = defaultdict(dict)
for model, field_mappings in registry['counter_fields'].items():
for field_name, counter_name in field_mappings.items():
fk_field = model._meta.get_field(field_name) # Interface.device
parent_model = fk_field.related_model # Device
related_query_name = fk_field.related_query_name() # 'interfaces'
models[parent_model][counter_name] = related_query_name
return models
def update_counts(self, model, field_name, related_query):
"""
Perform a bulk update for the given model and counter field. For example,
update_counts(Device, '_interface_count', 'interfaces')
will effectively set
Device.objects.update(_interface_count=Count('interfaces'))
"""
self.stdout.write(f'Updating {model.__name__} {field_name}...')
subquery = Subquery(
model.objects.filter(pk=OuterRef('pk')).annotate(_count=Count(related_query)).values('_count')
)
return model.objects.update(**{
field_name: subquery
})
def handle(self, *model_names, **options):
for model, mappings in self.collect_models().items():
for field_name, related_query in mappings.items():
self.update_counts(model, field_name, related_query)
self.stdout.write(self.style.SUCCESS('Finished.'))