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6347 Cache the number of each component type assigned to devices/VMs (#12632)
--------- Co-authored-by: Jeremy Stretch <jstretch@netboxlabs.com>
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from collections import defaultdict
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from django.core.management.base import BaseCommand
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from django.db.models import Count, OuterRef, Subquery
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from netbox.registry import registry
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class Command(BaseCommand):
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help = "Force a recalculation of all cached counter fields"
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@staticmethod
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def collect_models():
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"""
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Query the registry to find all models which have one or more counter fields. Return a mapping of counter fields
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to related query names for each model.
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"""
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models = defaultdict(dict)
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for model, field_mappings in registry['counter_fields'].items():
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for field_name, counter_name in field_mappings.items():
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fk_field = model._meta.get_field(field_name) # Interface.device
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parent_model = fk_field.related_model # Device
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related_query_name = fk_field.related_query_name() # 'interfaces'
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models[parent_model][counter_name] = related_query_name
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return models
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def update_counts(self, model, field_name, related_query):
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"""
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Perform a bulk update for the given model and counter field. For example,
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update_counts(Device, '_interface_count', 'interfaces')
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will effectively set
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Device.objects.update(_interface_count=Count('interfaces'))
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"""
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self.stdout.write(f'Updating {model.__name__} {field_name}...')
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subquery = Subquery(
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model.objects.filter(pk=OuterRef('pk')).annotate(_count=Count(related_query)).values('_count')
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)
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return model.objects.update(**{
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field_name: subquery
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})
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def handle(self, *model_names, **options):
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for model, mappings in self.collect_models().items():
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for field_name, related_query in mappings.items():
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self.update_counts(model, field_name, related_query)
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self.stdout.write(self.style.SUCCESS('Finished.'))
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