Исходный код django.contrib.postgres.aggregates.general

from django.contrib.postgres.fields import ArrayField
from django.db.models import Aggregate, BooleanField, JSONField, Value

from .mixins import OrderableAggMixin

__all__ = [
    'ArrayAgg', 'BitAnd', 'BitOr', 'BoolAnd', 'BoolOr', 'JSONBAgg', 'StringAgg',
]


[документация]class ArrayAgg(OrderableAggMixin, Aggregate):
    function = 'ARRAY_AGG'
    template = '%(function)s(%(distinct)s%(expressions)s %(ordering)s)'
    allow_distinct = True

    @property
    def output_field(self):
        return ArrayField(self.source_expressions[0].output_field)

    def convert_value(self, value, expression, connection):
        if not value:
            return []
        return value


[документация]class BitAnd(Aggregate):
    function = 'BIT_AND'


[документация]class BitOr(Aggregate):
    function = 'BIT_OR'


[документация]class BoolAnd(Aggregate):
    function = 'BOOL_AND'
    output_field = BooleanField()


[документация]class BoolOr(Aggregate):
    function = 'BOOL_OR'
    output_field = BooleanField()


[документация]class JSONBAgg(OrderableAggMixin, Aggregate):
    function = 'JSONB_AGG'
    template = '%(function)s(%(distinct)s%(expressions)s %(ordering)s)'
    allow_distinct = True
    output_field = JSONField()

    def convert_value(self, value, expression, connection):
        if not value:
            return '[]'
        return value


[документация]class StringAgg(OrderableAggMixin, Aggregate):
    function = 'STRING_AGG'
    template = '%(function)s(%(distinct)s%(expressions)s %(ordering)s)'
    allow_distinct = True

    def __init__(self, expression, delimiter, **extra):
        delimiter_expr = Value(str(delimiter))
        super().__init__(expression, delimiter_expr, **extra)

    def convert_value(self, value, expression, connection):
        if not value:
            return ''
        return value