Update multiple objects at once in Django?

Question

I am using Django 1.9. I have a Django table that represents the value of a particular measure, by organisation by month, with raw values and percentiles:

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Answer 1

As of Django 2.2, you can use the bulk_update() queryset method to efficiently update the given fields on the provided model instances, generally with one query:

objs = [
    Entry.objects.create(headline='Entry 1'),
    Entry.objects.create(headline='Entry 2'),
]
objs[0].headline = 'This is entry 1'
objs[1].headline = 'This is entry 2'
Entry.objects.bulk_update(objs, ['headline'])

In older versions of Django you could use update() with Case/When, e.g.:

from django.db.models import Case, When

Entry.objects.filter(
    pk__in=headlines  # `headlines` is a pk -> headline mapping
).update(
    headline=Case(*[When(pk=entry_pk, then=headline)
                    for entry_pk, headline in headlines.items()]))