INTPYTHON-974 Add support for MD5/SHA256 database functions

Author: timgraham

django_mongodb_backend/features.py

@@ -260,15 +260,13 @@ def django_test_expected_failures(self):
         "MongoDB does not support this database function.": {
             "db_functions.math.test_sign.SignTests",
             "db_functions.text.test_chr.ChrTests",
-            "db_functions.text.test_md5.MD5Tests",
             "db_functions.text.test_ord.OrdTests",
             "db_functions.text.test_pad.PadTests",
             "db_functions.text.test_repeat.RepeatTests",
             "db_functions.text.test_reverse.ReverseTests",
             "db_functions.text.test_right.RightTests",
             "db_functions.text.test_sha1.SHA1Tests",
             "db_functions.text.test_sha224.SHA224Tests",
-            "db_functions.text.test_sha256.SHA256Tests",
             "db_functions.text.test_sha384.SHA384Tests",
             "db_functions.text.test_sha512.SHA512Tests",
         },
@@ -460,6 +458,15 @@ def django_test_expected_failures(self):
     def django_test_skips(self):
         skips = super().django_test_skips
         skips.update(self._django_test_skips)
+        if not self.is_mongodb_8_3:
+            skips.update(
+                {
+                    "MD5 and SHA256 functions required MongoDB 8.3.+.": {
+                        "db_functions.text.test_md5.MD5Tests",
+                        "db_functions.text.test_sha256.SHA256Tests",
+                    }
+                }
+            )
         return skips
 
     # Tests that are expected to raise certain exceptions:
@@ -767,6 +774,10 @@ def mongodb_version(self):
     def is_mongodb_8_0(self):
         return self.mongodb_version >= (8, 0)
 
+    @cached_property
+    def is_mongodb_8_3(self):
+        return self.mongodb_version >= (8, 3)
+
     @cached_property
     def supports_search(self):
         """Does the server support MongoDB search queries and indexes?"""

django_mongodb_backend/functions.py

@@ -26,6 +26,8 @@
 )
 from django.db.models.functions.math import Ceil, Cot, Degrees, Log, Power, Radians, Random, Round
 from django.db.models.functions.text import (
+    MD5,
+    SHA256,
     Concat,
     ConcatPair,
     Left,
@@ -114,6 +116,30 @@ def func(self, compiler, connection):
     return {f"${operator}": lhs_mql}
 
 
+def hash_func(algorithm):
+    def wrapped(self, compiler, connection):
+        if not connection.features.is_mongodb_8_3:
+            raise NotSupportedError(f"{self.__class__.__name__} requires MongoDB 8.3+.")
+        lhs_mql = process_lhs(self, compiler, connection, as_expr=True)
+        return {
+            "$cond": {
+                "if": {"$eq": [lhs_mql, None]},
+                "then": None,
+                "else": {
+                    "$toLower": {
+                        "$convert": {
+                            "input": {"$hash": {"input": lhs_mql, "algorithm": algorithm}},
+                            "to": "string",
+                            "format": "hex",
+                        }
+                    }
+                },
+            }
+        }
+
+    return wrapped
+
+
 def left(self, compiler, connection):
     return self.get_substr().as_mql(compiler, connection, as_expr=True)
 
@@ -290,6 +316,7 @@ def register_functions():
     JSONArray.as_mql_expr = partialmethod(process_lhs, as_expr=True)
     Left.as_mql_expr = left
     Length.as_mql_expr = length
+    MD5.as_mql_expr = hash_func("md5")
     Log.as_mql_expr = log
     Lower.as_mql_expr = preserve_null("toLower")
     LTrim.as_mql_expr = trim("ltrim")
@@ -298,6 +325,7 @@ def register_functions():
     Replace.as_mql_expr = replace
     Round.as_mql_expr = round_
     RTrim.as_mql_expr = trim("rtrim")
+    SHA256.as_mql_expr = hash_func("sha256")
     StrIndex.as_mql_expr = str_index
     Substr.as_mql_expr = substr
     Trim.as_mql_expr = trim("trim")

docs/releases/6.0.x.rst

@@ -10,6 +10,11 @@ Django MongoDB Backend 6.0.x
 New features
 ------------
 
+- Added support for the following database functions:
+
+  -  :class:`~django.db.models.functions.MD5` (requires MongoDB 8.3+)
+  -  :class:`~django.db.models.functions.SHA256` (requires MongoDB 8.3+)
+
 - Added support for Django's warning when performing import-time queries.
 
 Bug fixes

docs/topics/known-issues.rst

@@ -79,14 +79,12 @@ Database functions
   - :class:`~django.db.models.functions.ExtractQuarter`
   - :class:`~django.db.models.functions.LPad`,
     :class:`~django.db.models.functions.RPad`
-  - :class:`~django.db.models.functions.MD5`
   - :class:`~django.db.models.functions.Ord`
   - :class:`~django.db.models.functions.Repeat`
   - :class:`~django.db.models.functions.Reverse`
   - :class:`~django.db.models.functions.Right`
   - :class:`~django.db.models.functions.SHA1`,
     :class:`~django.db.models.functions.SHA224`,
-    :class:`~django.db.models.functions.SHA256`,
     :class:`~django.db.models.functions.SHA384`,
     :class:`~django.db.models.functions.SHA512`
   - :class:`~django.db.models.functions.Sign`

tests/db_functions_/test_text.py

@@ -0,0 +1,18 @@
+from django.db import NotSupportedError
+from django.db.models.functions import MD5, SHA256
+from django.test import TestCase, skipIfDBFeature
+
+from .models import DTModel
+
+
+@skipIfDBFeature("is_mongodb_8_3")
+class HashFuncTests(TestCase):
+    def test_md5_requires_mongodb_8_3(self):
+        msg = "MD5 requires MongoDB 8.3+."
+        with self.assertRaisesMessage(NotSupportedError, msg):
+            DTModel.objects.annotate(md5=MD5("start_datetime")).get()
+
+    def test_sha256_requires_mongodb_8_3(self):
+        msg = "SHA256 requires MongoDB 8.3+."
+        with self.assertRaisesMessage(NotSupportedError, msg):
+            DTModel.objects.annotate(sha256=SHA256("start_datetime")).get()