Use DatabaseOperations.convert_trunc_expression()

Proposed for Django 6.1

Author: timgraham

django_mongodb_backend/functions.py

@@ -1,9 +1,6 @@
-from datetime import datetime
 from functools import partialmethod
 
-from django.conf import settings
 from django.db import NotSupportedError
-from django.db.models import DateField, DateTimeField, TimeField
 from django.db.models.expressions import Func
 from django.db.models.functions import JSONArray
 from django.db.models.functions.comparison import Cast, Coalesce, Greatest, Least, NullIf
@@ -209,36 +206,6 @@ def trunc(self, compiler, connection):
     return {"$dateTrunc": lhs_mql}
 
 
-_trunc_convert_value = TruncBase.convert_value
-
-
-def trunc_convert_value(self, value, expression, connection):
-    if connection.vendor == "mongodb":
-        # A custom TruncBase.convert_value() for MongoDB.
-        if value is None:
-            return None
-        convert_to_tz = settings.USE_TZ and self.get_tzname() != "UTC"
-        if isinstance(self.output_field, DateTimeField):
-            if convert_to_tz:
-                # Unlike other databases, MongoDB returns the value in UTC,
-                # so rather than setting the time zone equal to self.tzinfo,
-                # the value must be converted to tzinfo.
-                value = value.astimezone(self.tzinfo)
-        elif isinstance(value, datetime):
-            if isinstance(self.output_field, DateField):
-                if convert_to_tz:
-                    value = value.astimezone(self.tzinfo)
-                # Truncate for Trunc(..., output_field=DateField)
-                value = value.date()
-            elif isinstance(self.output_field, TimeField):
-                if convert_to_tz:
-                    value = value.astimezone(self.tzinfo)
-                # Truncate for Trunc(..., output_field=TimeField)
-                value = value.time()
-        return value
-    return _trunc_convert_value(self, value, expression, connection)
-
-
 def trunc_date(self, compiler, connection):
     # Cast to date rather than truncate to date.
     lhs_mql = process_lhs(self, compiler, connection, as_expr=True)
@@ -311,7 +278,6 @@ def register_functions():
     Substr.as_mql_expr = substr
     Trim.as_mql_expr = trim("trim")
     TruncBase.as_mql_expr = trunc
-    TruncBase.convert_value = trunc_convert_value
     TruncDate.as_mql_expr = trunc_date
     TruncTime.as_mql_expr = trunc_time
     Upper.as_mql_expr = preserve_null("toUpper")

django_mongodb_backend/operations.py

@@ -7,7 +7,7 @@
 from bson import Decimal128, Int64
 from django.conf import settings
 from django.core.exceptions import ImproperlyConfigured
-from django.db import DataError
+from django.db import DataError, models
 from django.db.backends.base.operations import BaseDatabaseOperations
 from django.db.models import TextField
 from django.db.models.expressions import Combinable, Expression
@@ -235,6 +235,29 @@ def convert_uuidfield_value(self, value, expression, connection):
             value = uuid.UUID(value)
         return value
 
+    def convert_trunc_expression(self, value, expression):
+        if value is None:
+            return None
+        convert_to_tz = settings.USE_TZ and expression.get_tzname() != "UTC"
+        if isinstance(expression.output_field, models.DateTimeField):
+            if convert_to_tz:
+                # Unlike other databases, MongoDB returns the value in UTC,
+                # so rather than setting the time zone equal to expression.tzinfo,
+                # the value must be converted to tzinfo.
+                value = value.astimezone(expression.tzinfo)
+        elif isinstance(value, datetime.datetime):
+            if isinstance(expression.output_field, models.DateField):
+                if convert_to_tz:
+                    value = value.astimezone(expression.tzinfo)
+                # Truncate for Trunc(..., output_field=DateField)
+                value = value.date()
+            elif isinstance(expression.output_field, models.TimeField):
+                if convert_to_tz:
+                    value = value.astimezone(expression.tzinfo)
+                # Truncate for Trunc(..., output_field=TimeField)
+                value = value.time()
+        return value
+
     def combine_expression(self, connector, sub_expressions):
         lhs, rhs = sub_expressions
         if connector == Combinable.BITLEFTSHIFT: