PostgreSQL specific aggregation functions¶

ArrayAgg¶

class ArrayAgg(expression, distinct=False, filter=None, default=None, ordering=(), **extra)¶

Returns a list of values, including nulls, concatenated into an array, or default if there are no values.

distinct¶

An optional boolean argument that determines if array values will be distinct. Defaults to False.

ordering¶

An optional string of a field name (with an optional "-" prefix which indicates descending order) or an expression (or a tuple or list of strings and/or expressions) that specifies the ordering of the elements in the result list.

Examples:

"some_field"
"-some_field"
from django.db.models import F

F("some_field").desc()

버전 4.0부터 폐지됨: If there are no rows and default is not provided, ArrayAgg returns an empty list instead of None. This behavior is deprecated and will be removed in Django 5.0. If you need it, explicitly set default to Value([]).

BitAnd¶

class BitAnd(expression, filter=None, default=None, **extra)¶

Returns an int of the bitwise AND of all non-null input values, or default if all values are null.

BitOr¶

class BitOr(expression, filter=None, default=None, **extra)¶

Returns an int of the bitwise OR of all non-null input values, or default if all values are null.

BitXor¶

class BitXor(expression, filter=None, default=None, **extra)¶

Returns an int of the bitwise XOR of all non-null input values, or default if all values are null. It requires PostgreSQL 14+.

BoolAnd¶

class BoolAnd(expression, filter=None, default=None, **extra)¶

Returns True, if all input values are true, default if all values are null or if there are no values, otherwise False.

Usage example:

class Comment(models.Model):
    body = models.TextField()
    published = models.BooleanField()
    rank = models.IntegerField()

>>> from django.db.models import Q
>>> from django.contrib.postgres.aggregates import BoolAnd
>>> Comment.objects.aggregate(booland=BoolAnd("published"))
{'booland': False}
>>> Comment.objects.aggregate(booland=BoolAnd(Q(rank__lt=100)))
{'booland': True}

BoolOr¶

class BoolOr(expression, filter=None, default=None, **extra)¶

Returns True if at least one input value is true, default if all values are null or if there are no values, otherwise False.

Usage example:

class Comment(models.Model):
    body = models.TextField()
    published = models.BooleanField()
    rank = models.IntegerField()

>>> from django.db.models import Q
>>> from django.contrib.postgres.aggregates import BoolOr
>>> Comment.objects.aggregate(boolor=BoolOr("published"))
{'boolor': True}
>>> Comment.objects.aggregate(boolor=BoolOr(Q(rank__gt=2)))
{'boolor': False}

JSONBAgg¶

class JSONBAgg(expressions, distinct=False, filter=None, default=None, ordering=(), **extra)¶

Returns the input values as a JSON array, or default if there are no values. You can query the result using key and index lookups.

distinct¶

An optional boolean argument that determines if array values will be distinct. Defaults to False.

ordering¶

An optional string of a field name (with an optional "-" prefix which indicates descending order) or an expression (or a tuple or list of strings and/or expressions) that specifies the ordering of the elements in the result list.

Examples are the same as for ArrayAgg.ordering.

Usage example:

class Room(models.Model):
    number = models.IntegerField(unique=True)


class HotelReservation(models.Model):
    room = models.ForeignKey("Room", on_delete=models.CASCADE)
    start = models.DateTimeField()
    end = models.DateTimeField()
    requirements = models.JSONField(blank=True, null=True)

>>> from django.contrib.postgres.aggregates import JSONBAgg
>>> Room.objects.annotate(
...     requirements=JSONBAgg(
...         "hotelreservation__requirements",
...         ordering="-hotelreservation__start",
...     )
... ).filter(requirements__0__sea_view=True).values("number", "requirements")
<QuerySet [{'number': 102, 'requirements': [
    {'parking': False, 'sea_view': True, 'double_bed': False},
    {'parking': True, 'double_bed': True}
]}]>

버전 4.0부터 폐지됨: If there are no rows and default is not provided, JSONBAgg returns an empty list instead of None. This behavior is deprecated and will be removed in Django 5.0. If you need it, explicitly set default to Value('[]').

StringAgg¶

class StringAgg(expression, delimiter, distinct=False, filter=None, default=None, ordering=())¶

Returns the input values concatenated into a string, separated by the delimiter string, or default if there are no values.

delimiter¶

Required argument. Needs to be a string.

distinct¶

An optional boolean argument that determines if concatenated values will be distinct. Defaults to False.

ordering¶

An optional string of a field name (with an optional "-" prefix which indicates descending order) or an expression (or a tuple or list of strings and/or expressions) that specifies the ordering of the elements in the result string.

Examples are the same as for ArrayAgg.ordering.

Usage example:

class Publication(models.Model):
    title = models.CharField(max_length=30)


class Article(models.Model):
    headline = models.CharField(max_length=100)
    publications = models.ManyToManyField(Publication)

>>> article = Article.objects.create(headline="NASA uses Python")
>>> article.publications.create(title="The Python Journal")
<Publication: Publication object (1)>
>>> article.publications.create(title="Science News")
<Publication: Publication object (2)>
>>> from django.contrib.postgres.aggregates import StringAgg
>>> Article.objects.annotate(
...     publication_names=StringAgg(
...         "publications__title",
...         delimiter=", ",
...         ordering="publications__title",
...     )
... ).values("headline", "publication_names")
<QuerySet [{
    'headline': 'NASA uses Python', 'publication_names': 'Science News, The Python Journal'
}]>

버전 4.0부터 폐지됨: If there are no rows and default is not provided, StringAgg returns an empty string instead of None. This behavior is deprecated and will be removed in Django 5.0. If you need it, explicitly set default to Value('').

y and x¶

The arguments y and x for all these functions can be the name of a field or an expression returning a numeric data. Both are required.

Corr¶

class Corr(y, x, filter=None, default=None)¶

Returns the correlation coefficient as a float, or default if there aren’t any matching rows.

CovarPop¶

class CovarPop(y, x, sample=False, filter=None, default=None)¶

Returns the population covariance as a float, or default if there aren’t any matching rows.

sample¶

Optional. By default CovarPop returns the general population covariance. However, if sample=True, the return value will be the sample population covariance.

RegrAvgX¶

class RegrAvgX(y, x, filter=None, default=None)¶

Returns the average of the independent variable (sum(x)/N) as a float, or default if there aren’t any matching rows.

RegrAvgY¶

class RegrAvgY(y, x, filter=None, default=None)¶

Returns the average of the dependent variable (sum(y)/N) as a float, or default if there aren’t any matching rows.

RegrCount¶

class RegrCount(y, x, filter=None)¶

Returns an int of the number of input rows in which both expressions are not null.

참고

The default argument is not supported.

RegrIntercept¶

class RegrIntercept(y, x, filter=None, default=None)¶

Returns the y-intercept of the least-squares-fit linear equation determined by the (x, y) pairs as a float, or default if there aren’t any matching rows.

RegrR2¶

class RegrR2(y, x, filter=None, default=None)¶

Returns the square of the correlation coefficient as a float, or default if there aren’t any matching rows.

RegrSlope¶

class RegrSlope(y, x, filter=None, default=None)¶

Returns the slope of the least-squares-fit linear equation determined by the (x, y) pairs as a float, or default if there aren’t any matching rows.

RegrSXX¶

class RegrSXX(y, x, filter=None, default=None)¶

Returns sum(x^2) - sum(x)^2/N (“sum of squares” of the independent variable) as a float, or default if there aren’t any matching rows.

RegrSXY¶

class RegrSXY(y, x, filter=None, default=None)¶

Returns sum(x*y) - sum(x) * sum(y)/N (“sum of products” of independent times dependent variable) as a float, or default if there aren’t any matching rows.

RegrSYY¶

class RegrSYY(y, x, filter=None, default=None)¶

Returns sum(y^2) - sum(y)^2/N (“sum of squares” of the dependent variable) as a float, or default if there aren’t any matching rows.