PostgreSQL specific aggregation functionsLink to this heading#

ArrayAggLink to this heading#

class ArrayAgg(expression, distinct=False, filter=None, default=None, order_by=(), **extra)Link to this definition#

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

distinctLink to this definition#

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

order_byLink to this definition#

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:

Code

from django.db.models import F

ArrayAgg("a_field", order_by="-some_field")
ArrayAgg("a_field", order_by=F("some_field").desc())

BitAndLink to this heading#

class BitAnd(expression, filter=None, default=None, **extra)Link to this definition#

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

BitOrLink to this heading#

class BitOr(expression, filter=None, default=None, **extra)Link to this definition#

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

BitXorLink to this heading#

class BitXor(expression, filter=None, default=None, **extra)Link to this definition#

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

BoolAndLink to this heading#

class BoolAnd(expression, filter=None, default=None, **extra)Link to this definition#

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

Usage example:

Code

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

Python console

>>> 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}

BoolOrLink to this heading#

class BoolOr(expression, filter=None, default=None, **extra)Link to this definition#

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:

Code

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

Python console

>>> 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}

JSONBAggLink to this heading#

class JSONBAgg(expressions, distinct=False, filter=None, default=None, order_by=(), **extra)Link to this definition#

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.

distinctLink to this definition#

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

order_byLink to this definition#

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.order_by.

Usage example:

Code

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)

Python console

>>> from django.contrib.postgres.aggregates import JSONBAgg
>>> Room.objects.annotate(
...     requirements=JSONBAgg(
...         "hotelreservation__requirements",
...         order_by="-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}
]}]>

StringAggLink to this heading#

class StringAgg(expression, delimiter, distinct=False, filter=None, default=None, order_by=())Link to this definition#

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

delimiterLink to this definition#

Required argument. A string, Value, or expression representing the string for separating values. For example, Value(",").

distinctLink to this definition#

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

order_byLink to this definition#

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.order_by.

Usage example:

Code

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


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

Python console

>>> 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=", ",
...         order_by="publications__title",
...     )
... ).values("headline", "publication_names")
<QuerySet [{
    'headline': 'NASA uses Python', 'publication_names': 'Science News, The Python Journal'
}]>

y and xLink to this heading#

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.

CorrLink to this heading#

class Corr(y, x, filter=None, default=None)Link to this definition#

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

CovarPopLink to this heading#

class CovarPop(y, x, sample=False, filter=None, default=None)Link to this definition#

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

sampleLink to this definition#

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

RegrAvgXLink to this heading#

class RegrAvgX(y, x, filter=None, default=None)Link to this definition#

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

RegrAvgYLink to this heading#

class RegrAvgY(y, x, filter=None, default=None)Link to this definition#

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

RegrCountLink to this heading#

class RegrCount(y, x, filter=None)Link to this definition#

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

RegrInterceptLink to this heading#

class RegrIntercept(y, x, filter=None, default=None)Link to this definition#

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.

RegrR2Link to this heading#

class RegrR2(y, x, filter=None, default=None)Link to this definition#

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

RegrSlopeLink to this heading#

class RegrSlope(y, x, filter=None, default=None)Link to this definition#

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.

RegrSXXLink to this heading#

class RegrSXX(y, x, filter=None, default=None)Link to this definition#

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.

RegrSXYLink to this heading#

class RegrSXY(y, x, filter=None, default=None)Link to this definition#

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.

RegrSYYLink to this heading#

class RegrSYY(y, x, filter=None, default=None)Link to this definition#

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.