Fixed #28562 -- Fixed DecimalValidator handling of positive exponent scientific notation.

3 files changed, 21 insertions, 13 deletions

diff --git a/django/core/validators.py b/django/core/validators.py
index b36ab60704..07236b7d26 100644
--- a/django/core/validators.py
+++ b/django/core/validators.py
@@ -414,15 +414,21 @@ class DecimalValidator:
 
     def __call__(self, value):
         digit_tuple, exponent = value.as_tuple()[1:]
-        decimals = abs(exponent)
-        # digit_tuple doesn't include any leading zeros.
-        digits = len(digit_tuple)
-        if decimals > digits:
-            # We have leading zeros up to or past the decimal point. Count
-            # everything past the decimal point as a digit. We do not count
-            # 0 before the decimal point as a digit since that would mean
-            # we would not allow max_digits = decimal_places.
-            digits = decimals
+        if exponent >= 0:
+            # A positive exponent adds that many trailing zeros.
+            digits = len(digit_tuple) + exponent
+            decimals = 0
+        else:
+            # If the absolute value of the negative exponent is larger than the
+            # number of digits, then it's the same as the number of digits,
+            # because it'll consume all of the digits in digit_tuple and then
+            # add abs(exponent) - len(digit_tuple) leading zeros after the
+            # decimal point.
+            if abs(exponent) > len(digit_tuple):
+                digits = decimals = abs(exponent)
+            else:
+                digits = len(digit_tuple)
+                decimals = abs(exponent)
         whole_digits = digits - decimals
 
         if self.max_digits is not None and digits > self.max_digits:
diff --git a/tests/forms_tests/field_tests/test_decimalfield.py b/tests/forms_tests/field_tests/test_decimalfield.py
index 1d5d27c8a0..d3fa222228 100644
--- a/tests/forms_tests/field_tests/test_decimalfield.py
+++ b/tests/forms_tests/field_tests/test_decimalfield.py
@@ -119,11 +119,12 @@ class DecimalFieldTest(FormFieldAssertionsMixin, SimpleTestCase):
             f.clean('1.1')
 
     def test_decimalfield_scientific(self):
-        f = DecimalField(max_digits=2, decimal_places=2)
-        self.assertEqual(f.clean('1E+2'), decimal.Decimal('1E+2'))
-        self.assertEqual(f.clean('1e+2'), decimal.Decimal('1E+2'))
+        f = DecimalField(max_digits=4, decimal_places=2)
         with self.assertRaisesMessage(ValidationError, "Ensure that there are no more"):
-            f.clean('0.546e+2')
+            f.clean('1E+2')
+        self.assertEqual(f.clean('1E+1'), decimal.Decimal('10'))
+        self.assertEqual(f.clean('1E-1'), decimal.Decimal('0.1'))
+        self.assertEqual(f.clean('0.546e+2'), decimal.Decimal('54.6'))
 
     def test_decimalfield_widget_attrs(self):
         f = DecimalField(max_digits=6, decimal_places=2)
diff --git a/tests/validators/tests.py b/tests/validators/tests.py
index 4a2fe0b0c4..220219789d 100644
--- a/tests/validators/tests.py
+++ b/tests/validators/tests.py
@@ -265,6 +265,7 @@ TEST_DATA = [
     (DecimalValidator(max_digits=3, decimal_places=1), Decimal('999'), ValidationError),
     (DecimalValidator(max_digits=4, decimal_places=1), Decimal('999'), None),
     (DecimalValidator(max_digits=20, decimal_places=2), Decimal('742403889818000000'), None),
+    (DecimalValidator(20, 2), Decimal('7.42403889818E+17'), None),
     (DecimalValidator(max_digits=20, decimal_places=2), Decimal('7424742403889818000000'), ValidationError),
     (DecimalValidator(max_digits=5, decimal_places=2), Decimal('7304E-1'), None),
     (DecimalValidator(max_digits=5, decimal_places=2), Decimal('7304E-3'), ValidationError),