Backported pallets-eco#548

CHANGES.rst

@@ -35,6 +35,8 @@ Unreleased
     if the given validators are both callable, and not classes (`#298`_, `#410`_)
 -   form.errors is not cached and will update if an error is appended to a field
     after access. (`#568`_)
+-   :class:`~wtforms.validators.NumberRange` correctly handle *not a number*
+    values. (`#505`_, `#548`_)
 
 .. _#238: https://github.com/wtforms/wtforms/issues/238
 .. _#239: https://github.com/wtforms/wtforms/issues/239
@@ -50,8 +52,10 @@ Unreleased
 .. _#410: https://github.com/wtforms/wtforms/pull/410
 .. _#475: https://github.com/wtforms/wtforms/pull/475
 .. _#463: https://github.com/wtforms/wtforms/pull/463
+.. _#505: https://github.com/wtforms/wtforms/pull/505
 .. _#523: https://github.com/wtforms/wtforms/pull/523
 .. _#524: https://github.com/wtforms/wtforms/pull/524
+.. _#548: https://github.com/wtforms/wtforms/pull/548
 .. _#483: https://github.com/wtforms/wtforms/pull/483
 .. _#485: https://github.com/wtforms/wtforms/pull/485
 .. _#471: https://github.com/wtforms/wtforms/pull/471

tests/validators.py

@@ -9,6 +9,7 @@
 )
 from functools import partial
 from tests.common import DummyField, grab_error_message, grab_stop_message
+import decimal
 
 
 class DummyForm(dict):
@@ -226,6 +227,11 @@ def test_number_range(self):
         self.assertEqual(onlymax(self.form, DummyField(30)), None)
         self.assertRaises(ValidationError, onlymax, self.form, DummyField(75))
 
+    def test_number_range_nan(self):
+        validator = NumberRange(0, 10)
+        for nan in (float("Nan"), decimal.Decimal("NaN")):
+            self.assertRaises(ValidationError, validator, self.form, DummyField(nan))
+
     def test_lazy_proxy(self):
         """Tests that the validators support lazy translation strings for messages."""
 

wtforms/validators.py

@@ -1,5 +1,6 @@
 from __future__ import unicode_literals
 
+import math
 import re
 import uuid
 import warnings
@@ -134,7 +135,7 @@ def __init__(self, min=None, max=None, message=None):
 
     def __call__(self, form, field):
         data = field.data
-        if data is None or (self.min is not None and data < self.min) or \
+        if data is None or math.isnan(data) or (self.min is not None and data < self.min) or \
                 (self.max is not None and data > self.max):
             message = self.message
             if message is None: