Fixed #30240 -- Added SHA1, SHA224, SHA256, SHA384, and SHA512 database functions.

Thanks Mariusz Felisiak and Tim Graham for reviews.

13 files changed, 439 insertions, 19 deletions

diff --git a/django/db/backends/sqlite3/base.py b/django/db/backends/sqlite3/base.py
index 9f30b75e6a..7552956cd9 100644
--- a/django/db/backends/sqlite3/base.py
+++ b/django/db/backends/sqlite3/base.py
@@ -226,6 +226,11 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         conn.create_function('REPEAT', 2, none_guard(operator.mul))
         conn.create_function('REVERSE', 1, none_guard(lambda x: x[::-1]))
         conn.create_function('RPAD', 3, _sqlite_rpad)
+        conn.create_function('SHA1', 1, none_guard(lambda x: hashlib.sha1(x.encode()).hexdigest()))
+        conn.create_function('SHA224', 1, none_guard(lambda x: hashlib.sha224(x.encode()).hexdigest()))
+        conn.create_function('SHA256', 1, none_guard(lambda x: hashlib.sha256(x.encode()).hexdigest()))
+        conn.create_function('SHA384', 1, none_guard(lambda x: hashlib.sha384(x.encode()).hexdigest()))
+        conn.create_function('SHA512', 1, none_guard(lambda x: hashlib.sha512(x.encode()).hexdigest()))
         conn.create_function('SIN', 1, none_guard(math.sin))
         conn.create_function('SQRT', 1, none_guard(math.sqrt))
         conn.create_function('TAN', 1, none_guard(math.tan))
diff --git a/django/db/models/functions/__init__.py b/django/db/models/functions/__init__.py
index 88bc43431a..fb899127d2 100644
--- a/django/db/models/functions/__init__.py
+++ b/django/db/models/functions/__init__.py
@@ -10,9 +10,9 @@ from .math import (
     Mod, Pi, Power, Radians, Round, Sin, Sqrt, Tan,
 )
 from .text import (
-    MD5, Chr, Concat, ConcatPair, Left, Length, Lower, LPad, LTrim, Ord,
-    Repeat, Replace, Reverse, Right, RPad, RTrim, StrIndex, Substr, Trim,
-    Upper,
+    MD5, SHA1, SHA224, SHA256, SHA384, SHA512, Chr, Concat, ConcatPair, Left,
+    Length, Lower, LPad, LTrim, Ord, Repeat, Replace, Reverse, Right, RPad,
+    RTrim, StrIndex, Substr, Trim, Upper,
 )
 from .window import (
     CumeDist, DenseRank, FirstValue, Lag, LastValue, Lead, NthValue, Ntile,
@@ -34,9 +34,10 @@ __all__ = [
     'Exp', 'Floor', 'Ln', 'Log', 'Mod', 'Pi', 'Power', 'Radians', 'Round',
     'Sin', 'Sqrt', 'Tan',
     # text
-    'MD5', 'Chr', 'Concat', 'ConcatPair', 'Left', 'Length', 'Lower', 'LPad',
-    'LTrim', 'Ord', 'Repeat', 'Replace', 'Reverse', 'Right', 'RPad', 'RTrim',
-    'StrIndex', 'Substr', 'Trim', 'Upper',
+    'MD5', 'SHA1', 'SHA224', 'SHA256', 'SHA384', 'SHA512', 'Chr', 'Concat',
+    'ConcatPair', 'Left', 'Length', 'Lower', 'LPad', 'LTrim', 'Ord', 'Repeat',
+    'Replace', 'Reverse', '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 58f920082b..2b2495c5c4 100644
--- a/django/db/models/functions/text.py
+++ b/django/db/models/functions/text.py
@@ -2,6 +2,7 @@ from django.db.models.expressions import Func, Value
 from django.db.models.fields import IntegerField
 from django.db.models.functions import Coalesce
 from django.db.models.lookups import Transform
+from django.db.utils import NotSupportedError
 
 
 class BytesToCharFieldConversionMixin:
@@ -20,6 +21,40 @@ class BytesToCharFieldConversionMixin:
         return super().convert_value(value, expression, connection)
 
 
+class MySQLSHA2Mixin:
+    def as_mysql(self, compiler, connection, **extra_content):
+        return super().as_sql(
+            compiler,
+            connection,
+            template='SHA2(%%(expressions)s, %s)' % self.function[3:],
+            **extra_content,
+        )
+
+
+class OracleHashMixin:
+    def as_oracle(self, compiler, connection, **extra_context):
+        return super().as_sql(
+            compiler,
+            connection,
+            template=(
+                "LOWER(RAWTOHEX(STANDARD_HASH(UTL_I18N.STRING_TO_RAW("
+                "%(expressions)s, 'AL32UTF8'), '%(function)s')))"
+            ),
+            **extra_context,
+        )
+
+
+class PostgreSQLSHAMixin:
+    def as_postgresql(self, compiler, connection, **extra_content):
+        return super().as_sql(
+            compiler,
+            connection,
+            template="ENCODE(DIGEST(%(expressions)s, '%(function)s'), 'hex')",
+            function=self.function.lower(),
+            **extra_content,
+        )
+
+
 class Chr(Transform):
     function = 'CHR'
     lookup_name = 'chr'
@@ -150,21 +185,10 @@ class LTrim(Transform):
     lookup_name = 'ltrim'
 
 
-class MD5(Transform):
+class MD5(OracleHashMixin, Transform):
     function = 'MD5'
     lookup_name = 'md5'
 
-    def as_oracle(self, compiler, connection, **extra_context):
-        return super().as_sql(
-            compiler,
-            connection,
-            template=(
-                "LOWER(RAWTOHEX(STANDARD_HASH(UTL_I18N.STRING_TO_RAW("
-                "%(expressions)s, 'AL32UTF8'), '%(function)s')))"
-            ),
-            **extra_context,
-        )
-
 
 class Ord(Transform):
     function = 'ASCII'
@@ -235,6 +259,34 @@ class RTrim(Transform):
     lookup_name = 'rtrim'
 
 
+class SHA1(OracleHashMixin, PostgreSQLSHAMixin, Transform):
+    function = 'SHA1'
+    lookup_name = 'sha1'
+
+
+class SHA224(MySQLSHA2Mixin, PostgreSQLSHAMixin, Transform):
+    function = 'SHA224'
+    lookup_name = 'sha224'
+
+    def as_oracle(self, compiler, connection, **extra_context):
+        raise NotSupportedError('SHA224 is not supported on Oracle.')
+
+
+class SHA256(MySQLSHA2Mixin, OracleHashMixin, PostgreSQLSHAMixin, Transform):
+    function = 'SHA256'
+    lookup_name = 'sha256'
+
+
+class SHA384(MySQLSHA2Mixin, OracleHashMixin, PostgreSQLSHAMixin, Transform):
+    function = 'SHA384'
+    lookup_name = 'sha384'
+
+
+class SHA512(MySQLSHA2Mixin, OracleHashMixin, PostgreSQLSHAMixin, Transform):
+    function = 'SHA512'
+    lookup_name = 'sha512'
+
+
 class StrIndex(Func):
     """
     Return a positive integer corresponding to the 1-indexed position of the
diff --git a/docs/ref/models/database-functions.txt b/docs/ref/models/database-functions.txt
index 46b41251a0..b79f7972cf 100644
--- a/docs/ref/models/database-functions.txt
+++ b/docs/ref/models/database-functions.txt
@@ -1441,6 +1441,41 @@ side.
 Similar to :class:`~django.db.models.functions.Trim`, but removes only trailing
 spaces.
 
+``SHA1``, ``SHA224``, ``SHA256``, ``SHA384``, and ``SHA512``
+------------------------------------------------------------
+
+.. class:: SHA1(expression, **extra)
+.. class:: SHA224(expression, **extra)
+.. class:: SHA256(expression, **extra)
+.. class:: SHA384(expression, **extra)
+.. class:: SHA512(expression, **extra)
+
+.. versionadded:: 3.0
+
+Accepts a single text field or expression and returns the particular hash of
+the string.
+
+They can also be registered as transforms as described in :class:`Length`.
+
+Usage example::
+
+    >>> from django.db.models.functions import SHA1
+    >>> Author.objects.create(name='Margaret Smith')
+    >>> author = Author.objects.annotate(name_sha1=SHA1('name')).get()
+    >>> print(author.name_sha1)
+    b87efd8a6c991c390be5a68e8a7945a7851c7e5c
+
+.. admonition:: PostgreSQL
+
+    The `pgcrypto extension <https://www.postgresql.org/docs/current/static/
+    pgcrypto.html>`_ must be installed. You can use the
+    :class:`~django.contrib.postgres.operations.CryptoExtension` migration
+    operation to install it.
+
+.. admonition:: Oracle
+
+    Oracle doesn't support the ``SHA224`` function.
+
 ``StrIndex``
 ------------
 
diff --git a/docs/releases/3.0.txt b/docs/releases/3.0.txt
index 3433d54183..71a8aef971 100644
--- a/docs/releases/3.0.txt
+++ b/docs/releases/3.0.txt
@@ -168,7 +168,12 @@ Migrations
 Models
 ~~~~~~
 
-* Added the :class:`~django.db.models.functions.MD5` database function.
+* Added hash database functions :class:`~django.db.models.functions.MD5`,
+  :class:`~django.db.models.functions.SHA1`,
+  :class:`~django.db.models.functions.SHA224`,
+  :class:`~django.db.models.functions.SHA256`,
+  :class:`~django.db.models.functions.SHA384`, and
+  :class:`~django.db.models.functions.SHA512`.
 
 * The new ``is_dst``  parameter of the
   :class:`~django.db.models.functions.Trunc` database functions determines the
diff --git a/tests/db_functions/migrations/0001_setup_extensions.py b/tests/db_functions/migrations/0001_setup_extensions.py
new file mode 100644
index 0000000000..0289055499
--- /dev/null
+++ b/tests/db_functions/migrations/0001_setup_extensions.py
@@ -0,0 +1,13 @@
+from unittest import mock
+
+from django.db import migrations
+
+try:
+    from django.contrib.postgres.operations import CryptoExtension
+except ImportError:
+    CryptoExtension = mock.Mock()
+
+
+class Migration(migrations.Migration):
+    # Required for the SHA database functions.
+    operations = [CryptoExtension()]
diff --git a/tests/db_functions/migrations/0002_create_test_models.py b/tests/db_functions/migrations/0002_create_test_models.py
new file mode 100644
index 0000000000..aa3e247bd5
--- /dev/null
+++ b/tests/db_functions/migrations/0002_create_test_models.py
@@ -0,0 +1,77 @@
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('db_functions', '0001_setup_extensions'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Author',
+            fields=[
+                ('name', models.CharField(max_length=50)),
+                ('alias', models.CharField(max_length=50, null=True, blank=True)),
+                ('goes_by', models.CharField(max_length=50, null=True, blank=True)),
+                ('age', models.PositiveSmallIntegerField(default=30)),
+            ],
+        ),
+        migrations.CreateModel(
+            name='Article',
+            fields=[
+                ('authors', models.ManyToManyField('db_functions.Author', related_name='articles')),
+                ('title', models.CharField(max_length=50)),
+                ('summary', models.CharField(max_length=200, null=True, blank=True)),
+                ('text', models.TextField()),
+                ('written', models.DateTimeField()),
+                ('published', models.DateTimeField(null=True, blank=True)),
+                ('updated', models.DateTimeField(null=True, blank=True)),
+                ('views', models.PositiveIntegerField(default=0)),
+            ],
+        ),
+        migrations.CreateModel(
+            name='Fan',
+            fields=[
+                ('name', models.CharField(max_length=50)),
+                ('age', models.PositiveSmallIntegerField(default=30)),
+                ('author', models.ForeignKey('db_functions.Author', models.CASCADE, related_name='fans')),
+                ('fan_since', models.DateTimeField(null=True, blank=True)),
+            ],
+        ),
+        migrations.CreateModel(
+            name='DTModel',
+            fields=[
+                ('name', models.CharField(max_length=32)),
+                ('start_datetime', models.DateTimeField(null=True, blank=True)),
+                ('end_datetime', models.DateTimeField(null=True, blank=True)),
+                ('start_date', models.DateField(null=True, blank=True)),
+                ('end_date', models.DateField(null=True, blank=True)),
+                ('start_time', models.TimeField(null=True, blank=True)),
+                ('end_time', models.TimeField(null=True, blank=True)),
+                ('duration', models.DurationField(null=True, blank=True)),
+            ],
+        ),
+        migrations.CreateModel(
+            name='DecimalModel',
+            fields=[
+                ('n1', models.DecimalField(decimal_places=2, max_digits=6)),
+                ('n2', models.DecimalField(decimal_places=2, max_digits=6)),
+            ],
+        ),
+        migrations.CreateModel(
+            name='IntegerModel',
+            fields=[
+                ('big', models.BigIntegerField(null=True, blank=True)),
+                ('normal', models.IntegerField(null=True, blank=True)),
+                ('small', models.SmallIntegerField(null=True, blank=True)),
+            ],
+        ),
+        migrations.CreateModel(
+            name='FloatModel',
+            fields=[
+                ('f1', models.FloatField(null=True, blank=True)),
+                ('f2', models.FloatField(null=True, blank=True)),
+            ],
+        ),
+    ]
diff --git a/tests/db_functions/migrations/__init__.py b/tests/db_functions/migrations/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/tests/db_functions/migrations/__init__.py
diff --git a/tests/db_functions/text/test_sha1.py b/tests/db_functions/text/test_sha1.py
new file mode 100644
index 0000000000..e34057bd6c
--- /dev/null
+++ b/tests/db_functions/text/test_sha1.py
@@ -0,0 +1,42 @@
+from django.db import connection
+from django.db.models import CharField
+from django.db.models.functions import SHA1
+from django.test import TestCase
+from django.test.utils import register_lookup
+
+from ..models import Author
+
+
+class SHA1Tests(TestCase):
+    @classmethod
+    def setUpTestData(cls):
+        Author.objects.bulk_create([
+            Author(alias='John Smith'),
+            Author(alias='Jordan Élena'),
+            Author(alias='皇帝'),
+            Author(alias=''),
+            Author(alias=None),
+        ])
+
+    def test_basic(self):
+        authors = Author.objects.annotate(
+            sha1_alias=SHA1('alias'),
+        ).values_list('sha1_alias', flat=True).order_by('pk')
+        self.assertSequenceEqual(
+            authors,
+            [
+                'e61a3587b3f7a142b8c7b9263c82f8119398ecb7',
+                '0781e0745a2503e6ded05ed5bc554c421d781b0c',
+                '198d15ea139de04060caf95bc3e0ec5883cba881',
+                'da39a3ee5e6b4b0d3255bfef95601890afd80709',
+                'da39a3ee5e6b4b0d3255bfef95601890afd80709'
+                if connection.features.interprets_empty_strings_as_nulls else None,
+            ],
+        )
+
+    def test_transform(self):
+        with register_lookup(CharField, SHA1):
+            authors = Author.objects.filter(
+                alias__sha1='e61a3587b3f7a142b8c7b9263c82f8119398ecb7',
+            ).values_list('alias', flat=True)
+            self.assertSequenceEqual(authors, ['John Smith'])
diff --git a/tests/db_functions/text/test_sha224.py b/tests/db_functions/text/test_sha224.py
new file mode 100644
index 0000000000..9ec0bf933f
--- /dev/null
+++ b/tests/db_functions/text/test_sha224.py
@@ -0,0 +1,53 @@
+import unittest
+
+from django.db import connection
+from django.db.models import CharField
+from django.db.models.functions import SHA224
+from django.db.utils import NotSupportedError
+from django.test import TestCase
+from django.test.utils import register_lookup
+
+from ..models import Author
+
+
+class SHA224Tests(TestCase):
+    @classmethod
+    def setUpTestData(cls):
+        Author.objects.bulk_create([
+            Author(alias='John Smith'),
+            Author(alias='Jordan Élena'),
+            Author(alias='皇帝'),
+            Author(alias=''),
+            Author(alias=None),
+        ])
+
+    @unittest.skipIf(connection.vendor == 'oracle', "Oracle doesn't support SHA224.")
+    def test_basic(self):
+        authors = Author.objects.annotate(
+            sha224_alias=SHA224('alias'),
+        ).values_list('sha224_alias', flat=True).order_by('pk')
+        self.assertSequenceEqual(
+            authors,
+            [
+                'a61303c220731168452cb6acf3759438b1523e768f464e3704e12f70',
+                '2297904883e78183cb118fc3dc21a610d60daada7b6ebdbc85139f4d',
+                'eba942746e5855121d9d8f79e27dfdebed81adc85b6bf41591203080',
+                'd14a028c2a3a2bc9476102bb288234c415a2b01f828ea62ac5b3e42f',
+                'd14a028c2a3a2bc9476102bb288234c415a2b01f828ea62ac5b3e42f'
+                if connection.features.interprets_empty_strings_as_nulls else None,
+            ],
+        )
+
+    @unittest.skipIf(connection.vendor == 'oracle', "Oracle doesn't support SHA224.")
+    def test_transform(self):
+        with register_lookup(CharField, SHA224):
+            authors = Author.objects.filter(
+                alias__sha224='a61303c220731168452cb6acf3759438b1523e768f464e3704e12f70',
+            ).values_list('alias', flat=True)
+            self.assertSequenceEqual(authors, ['John Smith'])
+
+    @unittest.skipUnless(connection.vendor == 'oracle', "Oracle doesn't support SHA224.")
+    def test_unsupported(self):
+        msg = 'SHA224 is not supported on Oracle.'
+        with self.assertRaisesMessage(NotSupportedError, msg):
+            Author.objects.annotate(sha224_alias=SHA224('alias')).first()
diff --git a/tests/db_functions/text/test_sha256.py b/tests/db_functions/text/test_sha256.py
new file mode 100644
index 0000000000..54ad841422
--- /dev/null
+++ b/tests/db_functions/text/test_sha256.py
@@ -0,0 +1,42 @@
+from django.db import connection
+from django.db.models import CharField
+from django.db.models.functions import SHA256
+from django.test import TestCase
+from django.test.utils import register_lookup
+
+from ..models import Author
+
+
+class SHA256Tests(TestCase):
+    @classmethod
+    def setUpTestData(cls):
+        Author.objects.bulk_create([
+            Author(alias='John Smith'),
+            Author(alias='Jordan Élena'),
+            Author(alias='皇帝'),
+            Author(alias=''),
+            Author(alias=None),
+        ])
+
+    def test_basic(self):
+        authors = Author.objects.annotate(
+            sha256_alias=SHA256('alias'),
+        ).values_list('sha256_alias', flat=True).order_by('pk')
+        self.assertSequenceEqual(
+            authors,
+            [
+                'ef61a579c907bbed674c0dbcbcf7f7af8f851538eef7b8e58c5bee0b8cfdac4a',
+                '6e4cce20cd83fc7c202f21a8b2452a68509cf24d1c272a045b5e0cfc43f0d94e',
+                '3ad2039e3ec0c88973ae1c0fce5a3dbafdd5a1627da0a92312c54ebfcf43988e',
+                'e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855',
+                'e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855'
+                if connection.features.interprets_empty_strings_as_nulls else None,
+            ],
+        )
+
+    def test_transform(self):
+        with register_lookup(CharField, SHA256):
+            authors = Author.objects.filter(
+                alias__sha256='ef61a579c907bbed674c0dbcbcf7f7af8f851538eef7b8e58c5bee0b8cfdac4a',
+            ).values_list('alias', flat=True)
+            self.assertSequenceEqual(authors, ['John Smith'])
diff --git a/tests/db_functions/text/test_sha384.py b/tests/db_functions/text/test_sha384.py
new file mode 100644
index 0000000000..95aa54cdbb
--- /dev/null
+++ b/tests/db_functions/text/test_sha384.py
@@ -0,0 +1,44 @@
+from django.db import connection
+from django.db.models import CharField
+from django.db.models.functions import SHA384
+from django.test import TestCase
+from django.test.utils import register_lookup
+
+from ..models import Author
+
+
+class SHA384Tests(TestCase):
+    @classmethod
+    def setUpTestData(cls):
+        Author.objects.bulk_create([
+            Author(alias='John Smith'),
+            Author(alias='Jordan Élena'),
+            Author(alias='皇帝'),
+            Author(alias=''),
+            Author(alias=None),
+        ])
+
+    def test_basic(self):
+        authors = Author.objects.annotate(
+            sha384_alias=SHA384('alias'),
+        ).values_list('sha384_alias', flat=True).order_by('pk')
+        self.assertSequenceEqual(
+            authors,
+            [
+                '9df976bfbcf96c66fbe5cba866cd4deaa8248806f15b69c4010a404112906e4ca7b57e53b9967b80d77d4f5c2982cbc8',
+                '72202c8005492016cc670219cce82d47d6d2d4273464c742ab5811d691b1e82a7489549e3a73ffa119694f90678ba2e3',
+                'eda87fae41e59692c36c49e43279c8111a00d79122a282a944e8ba9a403218f049a48326676a43c7ba378621175853b0',
+                '38b060a751ac96384cd9327eb1b1e36a21fdb71114be07434c0cc7bf63f6e1da274edebfe76f65fbd51ad2f14898b95b',
+                '38b060a751ac96384cd9327eb1b1e36a21fdb71114be07434c0cc7bf63f6e1da274edebfe76f65fbd51ad2f14898b95b'
+                if connection.features.interprets_empty_strings_as_nulls else None,
+            ],
+        )
+
+    def test_transform(self):
+        with register_lookup(CharField, SHA384):
+            authors = Author.objects.filter(
+                alias__sha384=(
+                    '9df976bfbcf96c66fbe5cba866cd4deaa8248806f15b69c4010a404112906e4ca7b57e53b9967b80d77d4f5c2982cbc8'
+                ),
+            ).values_list('alias', flat=True)
+            self.assertSequenceEqual(authors, ['John Smith'])
diff --git a/tests/db_functions/text/test_sha512.py b/tests/db_functions/text/test_sha512.py
new file mode 100644
index 0000000000..aa0d1e6fdd
--- /dev/null
+++ b/tests/db_functions/text/test_sha512.py
@@ -0,0 +1,51 @@
+from django.db import connection
+from django.db.models import CharField
+from django.db.models.functions import SHA512
+from django.test import TestCase
+from django.test.utils import register_lookup
+
+from ..models import Author
+
+
+class SHA512Tests(TestCase):
+    @classmethod
+    def setUpTestData(cls):
+        Author.objects.bulk_create([
+            Author(alias='John Smith'),
+            Author(alias='Jordan Élena'),
+            Author(alias='皇帝'),
+            Author(alias=''),
+            Author(alias=None),
+        ])
+
+    def test_basic(self):
+        authors = Author.objects.annotate(
+            sha512_alias=SHA512('alias'),
+        ).values_list('sha512_alias', flat=True).order_by('pk')
+        self.assertSequenceEqual(
+            authors,
+            [
+                'ed014a19bb67a85f9c8b1d81e04a0e7101725be8627d79d02ca4f3bd803f33cf'
+                '3b8fed53e80d2a12c0d0e426824d99d110f0919298a5055efff040a3fc091518',
+                'b09c449f3ba49a32ab44754982d4749ac938af293e4af2de28858858080a1611'
+                '2b719514b5e48cb6ce54687e843a4b3e69a04cdb2a9dc99c3b99bdee419fa7d0',
+                'b554d182e25fb487a3f2b4285bb8672f98956b5369138e681b467d1f079af116'
+                '172d88798345a3a7666faf5f35a144c60812d3234dcd35f444624f2faee16857',
+                'cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce'
+                '47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e',
+                'cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce'
+                '47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e'
+                if connection.features.interprets_empty_strings_as_nulls else None,
+            ],
+        )
+
+    def test_transform(self):
+        with register_lookup(CharField, SHA512):
+            authors = Author.objects.filter(
+                alias__sha512=(
+                    'ed014a19bb67a85f9c8b1d81e04a0e7101725be8627d79d02ca4f3bd8'
+                    '03f33cf3b8fed53e80d2a12c0d0e426824d99d110f0919298a5055eff'
+                    'f040a3fc091518'
+                ),
+            ).values_list('alias', flat=True)
+            self.assertSequenceEqual(authors, ['John Smith'])