store DecimalField as Decimal128

Author: timgraham

django_mongodb/features.py

@@ -33,10 +33,6 @@ class DatabaseFeatures(BaseDatabaseFeatures):
         "lookup.tests.LookupTests.test_exact_none_transform",
         # "Save with update_fields did not affect any rows."
         "basic.tests.SelectOnSaveTests.test_select_on_save_lying_update",
-        # filtering on large decimalfield, see https://code.djangoproject.com/ticket/34590
-        # for some background.
-        "model_fields.test_decimalfield.DecimalFieldTests.test_lookup_decimal_larger_than_max_digits",
-        "model_fields.test_decimalfield.DecimalFieldTests.test_lookup_really_big_value",
         # 'TruncDate' object has no attribute 'as_mql'.
         "model_fields.test_datetimefield.DateTimeFieldTests.test_lookup_date_with_use_tz",
         "model_fields.test_datetimefield.DateTimeFieldTests.test_lookup_date_without_use_tz",

django_mongodb/operations.py

@@ -1,7 +1,7 @@
 import datetime
-import decimal
 import uuid
 
+from bson.decimal128 import Decimal128
 from django.conf import settings
 from django.db.backends.base.operations import BaseDatabaseOperations
 from django.utils import timezone
@@ -21,6 +21,10 @@ def adapt_datetimefield_value(self, value):
             value = timezone.make_aware(value)
         return value
 
+    def adapt_decimalfield_value(self, value, max_digits=None, decimal_places=None):
+        """Store DecimalField as Decimal128."""
+        return Decimal128(value)
+
     def adapt_timefield_value(self, value):
         """Store TimeField as datetime."""
         if value is None:
@@ -56,7 +60,8 @@ def convert_datetimefield_value(self, value, expression, connection):
 
     def convert_decimalfield_value(self, value, expression, connection):
         if value is not None:
-            value = decimal.Decimal(value)
+            # from Decimal128 to decimal.Decimal()
+            value = value.to_decimal()
         return value
 
     def convert_timefield_value(self, value, expression, connection):