Fixed #24656 -- Added missing imports to query expressions doc. (37682368) · Commits · Dom Sekotill / django

AUTHORS

+1 −0

Original line number	Diff line number	Diff line
		@@ -522,6 +522,7 @@ answer newbie questions, and generally made Django that much better:
		Niclas Olofsson <n@niclasolofsson.se>
		Nicola Larosa <nico@teknico.net>
		Nicolas Lara <nicolaslara@gmail.com>
		Nicolas Noé <nicolas@niconoe.eu>
		Niran Babalola <niran@niran.org>
		Nis Jørgensen <nis@superlativ.dk>
		Nowell Strite <http://nowell.strite.org/>

docs/ref/models/expressions.txt

+17 −0

Original line number	Diff line number	Diff line
		@@ -26,6 +26,9 @@ Some examples

		.. code-block:: python

		from django.db.models import F, Count
		from django.db.models.functions import Length

		# Find companies that have more employees than chairs.
		Company.objects.filter(num_employees__gt=F('num_chairs'))

		@@ -62,6 +65,12 @@ Some examples
		Built-in Expressions
		====================

		.. note::

		These expressions are defined in ``django.db.models.expressions`` and
		``django.db.models.aggregates``, but for convenience they're available and
		usually imported from :mod:`django.db.models`.

		``F()`` expressions
		-------------------

		@@ -88,6 +97,7 @@ into memory and manipulated it using familiar Python operators, and then saved
		the object back to the database. But instead we could also have done::

		from django.db.models import F

		reporter = Reporters.objects.get(name='Tintin')
		reporter.stories_filed = F('stories_filed') + 1
		reporter.save()
		@@ -194,6 +204,8 @@ directly support ``output_field`` you will need to wrap the expression with
		database functions like ``COALESCE`` and ``LOWER``, or aggregates like ``SUM``.
		They can be used directly::

		from django.db.models import Func, F

		queryset.annotate(field_lower=Func(F('field'), function='LOWER'))

		or they can be used to build a library of database functions::
		@@ -259,6 +271,8 @@ like ``Sum()`` and ``Count()``, inherit from ``Aggregate()``.
		Since ``Aggregate``\s are expressions and wrap expressions, you can represent
		some complex computations::

		from django.db.models import Count

		Company.objects.annotate(
		managers_required=(Count('num_employees') / 4) + Count('num_managers'))

		@@ -314,6 +328,8 @@ Creating your own aggregate is extremely easy. At a minimum, you need
		to define ``function``, but you can also completely customize the
		SQL that is generated. Here's a brief example::

		from django.db.models import Aggregate

		class Count(Aggregate):
		# supports COUNT(distinct field)
		function = 'COUNT'
		@@ -578,6 +594,7 @@ to play nice with other query expressions::

		Let's see how it works::

		>>> from django.db.models import F, Value, CharField
		>>> qs = Company.objects.annotate(
		... tagline=Coalesce([
		... F('motto'),