class TruncMonth(expression, output_field=None, tzinfo=None, **extra) [source]
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kind = 'month'
These are logically equivalent to Trunc('date_field', kind). They truncate all parts of the date up to kind which allows grouping or filtering dates with less precision. expression can have an output_field of either DateField or DateTimeField.
Since DateFields don’t have a time component, only Trunc subclasses that deal with date-parts can be used with DateField:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | >>> from datetime import datetime>>> from django.db.models import Count>>> from django.db.models.functions import TruncMonth, TruncYear>>> from django.utils import timezone>>> start1 = datetime(2014, 6, 15, 14, 30, 50, 321, tzinfo=timezone.utc)>>> start2 = datetime(2015, 6, 15, 14, 40, 2, 123, tzinfo=timezone.utc)>>> start3 = datetime(2015, 12, 31, 17, 5, 27, 999, tzinfo=timezone.utc)>>> Experiment.objects.create(start_datetime=start1, start_date=start1.date())>>> Experiment.objects.create(start_datetime=start2, start_date=start2.date())>>> Experiment.objects.create(start_datetime=start3, start_date=start3.date())>>> experiments_per_year = Experiment.objects.annotate(... year=TruncYear('start_date')).values('year').annotate(... experiments=Count('id'))>>> for exp in experiments_per_year:... print(exp['year'], exp['experiments'])...2014-01-01 12015-01-01 2>>> import pytz>>> melb = pytz.timezone('Australia/Melbourne')>>> experiments_per_month = Experiment.objects.annotate(... month=TruncMonth('start_datetime', tzinfo=melb)).values('month').annotate(... experiments=Count('id'))>>> for exp in experiments_per_month:... print(exp['month'], exp['experiments'])...2015-06-01 00:00:00+10:00 12016-01-01 00:00:00+11:00 12014-06-01 00:00:00+10:00 1 |
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