{"title":"PostgreSQL specific query expressions","version":"6.0","locale":"el","docname":"ref/contrib/postgres/expressions","url":"/el/6.0/ref/contrib/postgres/expressions/","canonical":"https://djangodocs.dev/el/6.0/ref/contrib/postgres/expressions/","summary":"These expressions are available from the django.contrib.postgres.expressions module. ArraySubquery() expressions Link to this heading # class ArraySubquery (…","html":"

PostgreSQL specific query expressionsLink to this heading#

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These expressions are available from the\ndjango.contrib.postgres.expressions module.

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ArraySubquery() expressionsLink to this heading#

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\nclass ArraySubquery(queryset)Link to this definition#
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ArraySubquery is a Subquery that uses the\nPostgreSQL ARRAY constructor to build a list of values from the queryset,\nwhich must use QuerySet.values() to return only a single column.

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This class differs from ArrayAgg\nin the way that it does not act as an aggregate function and does not require\nan SQL GROUP BY clause to build the list of values.

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For example, if you want to annotate all related books to an author as JSON\nobjects:

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Python console
>>> from django.db.models import OuterRef\n>>> from django.db.models.functions import JSONObject\n>>> from django.contrib.postgres.expressions import ArraySubquery\n>>> books = Book.objects.filter(author=OuterRef("pk")).values(\n...     json=JSONObject(title="title", pages="pages")\n... )\n>>> author = Author.objects.annotate(books=ArraySubquery(books)).first()\n>>> author.books\n[{'title': 'Solaris', 'pages': 204}, {'title': 'The Cyberiad', 'pages': 295}]\n
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