Refs #28643 -- Added LPad and RPad database functions.

Thanks Tim Graham for the review.

3 files changed, 30 insertions, 4 deletions

diff --git a/django/db/backends/sqlite3/base.py b/django/db/backends/sqlite3/base.py
index 996ec1e09b..3989028930 100644
--- a/django/db/backends/sqlite3/base.py
+++ b/django/db/backends/sqlite3/base.py
@@ -169,6 +169,8 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         conn.create_function("regexp", 2, _sqlite_regexp)
         conn.create_function("django_format_dtdelta", 3, _sqlite_format_dtdelta)
         conn.create_function("django_power", 2, _sqlite_power)
+        conn.create_function('LPAD', 3, _sqlite_lpad)
+        conn.create_function('RPAD', 3, _sqlite_rpad)
         conn.execute('PRAGMA foreign_keys = ON')
         return conn
 
@@ -467,5 +469,15 @@ def _sqlite_regexp(re_pattern, re_string):
     return bool(re.search(re_pattern, str(re_string))) if re_string is not None else False
 
 
+def _sqlite_lpad(text, length, fill_text):
+    if len(text) >= length:
+        return text[:length]
+    return (fill_text * length)[:length - len(text)] + text
+
+
+def _sqlite_rpad(text, length, fill_text):
+    return (text + fill_text * length)[:length]
+
+
 def _sqlite_power(x, y):
     return x ** y
diff --git a/django/db/models/functions/__init__.py b/django/db/models/functions/__init__.py
index 5528be8c48..a0f5a9e8b2 100644
--- a/django/db/models/functions/__init__.py
+++ b/django/db/models/functions/__init__.py
@@ -6,8 +6,8 @@ from .datetime import (
     TruncQuarter, TruncSecond, TruncTime, TruncWeek, TruncYear,
 )
 from .text import (
-    Chr, Concat, ConcatPair, Left, Length, Lower, LTrim, Ord, Replace, Right,
-    RTrim, StrIndex, Substr, Trim, Upper,
+    Chr, Concat, ConcatPair, Left, Length, Lower, LPad, LTrim, Ord, Replace,
+    Right, RPad, RTrim, StrIndex, Substr, Trim, Upper,
 )
 from .window import (
     CumeDist, DenseRank, FirstValue, Lag, LastValue, Lead, NthValue, Ntile,
@@ -24,8 +24,9 @@ __all__ = [
     'TruncMinute', 'TruncMonth', 'TruncQuarter', 'TruncSecond', 'TruncTime',
     'TruncWeek', 'TruncYear',
     # text
-    'Chr', 'Concat', 'ConcatPair', 'Left', 'Length', 'Lower', 'LTrim', 'Ord',
-    'Replace', 'Right', 'RTrim', 'StrIndex', 'Substr', 'Trim', 'Upper',
+    'Chr', 'Concat', 'ConcatPair', 'Left', 'Length', 'Lower', 'LPad', 'LTrim',
+    'Ord', 'Replace', 'Right', 'RPad', 'RTrim', 'StrIndex', 'Substr', 'Trim',
+    'Upper',
     # window
     'CumeDist', 'DenseRank', 'FirstValue', 'Lag', 'LastValue', 'Lead',
     'NthValue', 'Ntile', 'PercentRank', 'Rank', 'RowNumber',
diff --git a/django/db/models/functions/text.py b/django/db/models/functions/text.py
index 614522017f..c57545bc6a 100644
--- a/django/db/models/functions/text.py
+++ b/django/db/models/functions/text.py
@@ -110,6 +110,15 @@ class Lower(Transform):
     lookup_name = 'lower'
 
 
+class LPad(Func):
+    function = 'LPAD'
+
+    def __init__(self, expression, length, fill_text=Value(' '), **extra):
+        if not hasattr(length, 'resolve_expression') and length < 0:
+            raise ValueError("'length' must be greater or equal to 0.")
+        super().__init__(expression, length, fill_text, **extra)
+
+
 class LTrim(Transform):
     function = 'LTRIM'
     lookup_name = 'ltrim'
@@ -141,6 +150,10 @@ class Right(Left):
         return Substr(self.source_expressions[0], self.source_expressions[1] * Value(-1))
 
 
+class RPad(LPad):
+    function = 'RPAD'
+
+
 class RTrim(Transform):
     function = 'RTRIM'
     lookup_name = 'rtrim'