feat: enforce Decimal type in min_value and max_value arguments of De…

…cimalField (#8972)

* add warning when min_value and max_value are not decimal

* remove redundant module name in log

---------

Co-authored-by: ismaeljs <>

rest_framework/fields.py

@@ -4,6 +4,7 @@
 import decimal
 import functools
 import inspect
+import logging
 import re
 import uuid
 from collections.abc import Mapping
@@ -38,6 +39,8 @@
 from rest_framework.utils.timezone import valid_datetime
 from rest_framework.validators import ProhibitSurrogateCharactersValidator
 
+logger = logging.getLogger("rest_framework.fields")
+
 
 class empty:
  """
@@ -990,6 +993,11 @@ def __init__(self, max_digits, decimal_places, coerce_to_string=None, max_value=
  self.max_value = max_value
  self.min_value = min_value
 
+ if self.max_value is not None and not isinstance(self.max_value, decimal.Decimal):
+ logger.warning("max_value in DecimalField should be Decimal type.")
+ if self.min_value is not None and not isinstance(self.min_value, decimal.Decimal):
+ logger.warning("min_value in DecimalField should be Decimal type.")
+
  if self.max_digits is not None and self.decimal_places is not None:
  self.max_whole_digits = self.max_digits - self.decimal_places
  else:

tests/test_fields.py

@@ -1216,6 +1216,17 @@ class TestMinMaxDecimalField(FieldValues):
  min_value=10, max_value=20
  )
 
+ def test_warning_when_not_decimal_types(self, caplog):
+ import logging
+ serializers.DecimalField(
+ max_digits=3, decimal_places=1,
+ min_value=10, max_value=20
+ )
+ assert caplog.record_tuples == [
+ ("rest_framework.fields", logging.WARNING, "max_value in DecimalField should be Decimal type."),
+ ("rest_framework.fields", logging.WARNING, "min_value in DecimalField should be Decimal type.")
+ ]
+
 
 class TestAllowEmptyStrDecimalFieldWithValidators(FieldValues):
  """