Use it like below:
totals = MyClass.aggregate(
is_enabled_yes=CountCase('is_enabled', when=True),
is_enabled_no=CountCase('is_enabled', when=False),
count_if=CountCase('id', case="another_field in ('a','b')", when=True),
)
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 | from django.db import models
class SQLCountCase(models.sql.aggregates.Aggregate):
is_ordinal = True
sql_function = 'COUNT'
sql_template = "%(function)s(CASE %(case)s WHEN %(when)s THEN 1 ELSE null END)"
def __init__(self, col, **extra):
if isinstance(extra['when'], basestring):
extra['when'] = "'%s'"%extra['when']
if not extra.get('case', None):
extra['case'] = '"%s"."%s"'%(extra['source'].model._meta.db_table, extra['source'].name)
if extra['when'] is None:
extra['when'] = True
extra['case'] += ' IS NULL '
super(SQLCountCase, self).__init__(col, **extra)
class CountCase(models.Aggregate):
name = 'COUNT'
def add_to_query(self, query, alias, col, source, is_summary):
aggregate = SQLCountCase(col, source=source, is_summary=is_summary, **self.extra)
query.aggregates[alias] = aggregate
|
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Comments
Fixed bug with NULL cases
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