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@w495
Forked from ludoo/aggregate_concat.py
Last active April 18, 2017 17:09
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Django aggregates GROUP_CONCAT support for MySQL
"""
From http://harkablog.com/inside-the-django-orm-aggregates.html
with a couple of fixes.
Usage: MyModel.objects.all().annotate(new_attribute=GroupConcat('related__attribute', separator=':')
"""
from django.db.models import Aggregate
from django.db.models.sql.aggregates import Aggregate as SQLAggregate
class GroupConcat(Aggregate):
def add_to_query(self, query, alias, col, source, is_summary):
aggregate = SQLGroupConcat(col, source=source, is_summary=is_summary, **self.extra)
query.aggregates[alias] = aggregate
class SQLGroupConcat(SQLAggregate):
sql_function = 'GROUP_CONCAT'
@property
def sql_template(self):
separator = self.extra.get('separator')
if separator:
return '%(function)s(%(field)s SEPARATOR "%(separator)s")'
else:
return '%(function)s(%(field)s)'
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