Fixed #29049 -- Added slicing notation to F expressions.

Co-authored-by: Priyansh Saxena <askpriyansh@gmail.com>
Co-authored-by: Niclas Olofsson <n@niclasolofsson.se>
Co-authored-by: David Smith <smithdc@gmail.com>
Co-authored-by: Mariusz Felisiak <felisiak.mariusz@gmail.com>
Co-authored-by: Abhinav Yadav <abhinav.sny.2002@gmail.com>

2 files changed, 30 insertions, 0 deletions

diff --git a/docs/ref/models/expressions.txt b/docs/ref/models/expressions.txt
index 9d85442d9c..67baef7dfc 100644
--- a/docs/ref/models/expressions.txt
+++ b/docs/ref/models/expressions.txt
@@ -183,6 +183,28 @@ the field value of each one, and saving each one back to the database::
 * getting the database, rather than Python, to do work
 * reducing the number of queries some operations require
 
+.. _slicing-using-f:
+
+Slicing ``F()`` expressions
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. versionadded:: 5.1
+
+For string-based fields, text-based fields, and
+:class:`~django.contrib.postgres.fields.ArrayField`, you can use Python's
+array-slicing syntax. The indices are 0-based and the ``step`` argument to
+``slice`` is not supported. For example:
+
+.. code-block:: pycon
+
+    >>> # Replacing a name with a substring of itself.
+    >>> writer = Writers.objects.get(name="Priyansh")
+    >>> writer.name = F("name")[1:5]
+    >>> writer.save()
+    >>> writer.refresh_from_db()
+    >>> writer.name
+    'riya'
+
 .. _avoiding-race-conditions-using-f:
 
 Avoiding race conditions using ``F()``
diff --git a/docs/releases/5.1.txt b/docs/releases/5.1.txt
index cc72346eef..b825e9be4f 100644
--- a/docs/releases/5.1.txt
+++ b/docs/releases/5.1.txt
@@ -184,6 +184,14 @@ Models
 * :meth:`.QuerySet.order_by` now supports ordering by annotation transforms
   such as ``JSONObject`` keys and ``ArrayAgg`` indices.
 
+* :class:`F() <django.db.models.F>` and :class:`OuterRef()
+  <django.db.models.OuterRef>` expressions that output
+  :class:`~django.db.models.CharField`, :class:`~django.db.models.EmailField`,
+  :class:`~django.db.models.SlugField`, :class:`~django.db.models.URLField`,
+  :class:`~django.db.models.TextField`, or
+  :class:`~django.contrib.postgres.fields.ArrayField` can now be :ref:`sliced
+  <slicing-using-f>`.
+
 Requests and Responses
 ~~~~~~~~~~~~~~~~~~~~~~