Fixed #34606 -- Fixed Right() function with zero length on Oracle and SQLite.

wolkiewiczk · web-flow · commit 91be6e1818c3 · 2023-05-31T11:57:40.000+01:00
diff --git a/AUTHORS b/AUTHORS
@@ -545,6 +545,7 @@ answer newbie questions, and generally made Django that much better:
     Justin Michalicek <jmichalicek@gmail.com>
     Justin Myles Holmes <justin@slashrootcafe.com>
     Jyrki Pulliainen <jyrki.pulliainen@gmail.com>
+    Kacper Wolkiewicz <kac.wolkiewicz@gmail.com>
     Kadesarin Sanjek
     Kapil Bansal <kapilbansal.gbpecdelhi@gmail.com>
     Karderio <karderio@gmail.com>
diff --git a/django/db/models/functions/text.py b/django/db/models/functions/text.py
@@ -276,7 +276,9 @@ class Right(Left):
 
     def get_substr(self):
         return Substr(
-            self.source_expressions[0], self.source_expressions[1] * Value(-1)
+            self.source_expressions[0],
+            self.source_expressions[1] * Value(-1),
+            self.source_expressions[1],
         )
 
 
diff --git a/tests/db_functions/text/test_right.py b/tests/db_functions/text/test_right.py
@@ -1,5 +1,6 @@
+from django.db import connection
 from django.db.models import IntegerField, Value
-from django.db.models.functions import Lower, Right
+from django.db.models.functions import Length, Lower, Right
 from django.test import TestCase
 
 from ..models import Author
@@ -26,6 +27,21 @@ def test_invalid_length(self):
         with self.assertRaisesMessage(ValueError, "'length' must be greater than 0"):
             Author.objects.annotate(raises=Right("name", 0))
 
+    def test_zero_length(self):
+        Author.objects.create(name="Tom", alias="tom")
+        authors = Author.objects.annotate(
+            name_part=Right("name", Length("name") - Length("alias"))
+        )
+        self.assertQuerySetEqual(
+            authors.order_by("name"),
+            [
+                "mith",
+                "" if connection.features.interprets_empty_strings_as_nulls else None,
+                "",
+            ],
+            lambda a: a.name_part,
+        )
+
     def test_expressions(self):
         authors = Author.objects.annotate(
             name_part=Right("name", Value(3, output_field=IntegerField()))

-Original file line number
+Diff line change
     Justin Michalicek <[email protected]>
     Justin Myles Holmes <[email protected]>
     Jyrki Pulliainen <[email protected]>
 +    Kacper Wolkiewicz <[email protected]>
     Kadesarin Sanjek
     Kapil Bansal <[email protected]>
     Karderio <[email protected]>
Original file line number	Diff line number	Diff line change
`@@ -276,7 +276,9 @@ class Right(Left):`
`276`	`276`
`277`	`277`	`def get_substr(self):`
`278`	`278`	`return Substr(`
`279`		`- self.source_expressions[0], self.source_expressions[1] * Value(-1)`
	`279`	`+ self.source_expressions[0],`
	`280`	`+ self.source_expressions[1] * Value(-1),`
	`281`	`+ self.source_expressions[1],`
`280`	`282`	`)`
`281`	`283`
`282`	`284`