Ticket #15789: patch.diff

django/template/defaultfilters.py

@@ -2 +2 @@
 
 import re
 import random as random_module
-from decimal import Decimal, InvalidOperation, ROUND_HALF_UP
+from decimal import Decimal, InvalidOperation, Context, ROUND_HALF_UP
 from functools import wraps
 
 from django.template.base import Variable, Library
@@ -148 +148 @@
     else:
         exp = Decimal(u'1.0') / (Decimal(10) ** abs(p))
     try:
+        # Set the precission to the necessary digits to avoid an exception.
+        # Bigger of the number of digits and the number of actual decimals
+        prec = max(abs(arg) + 1, abs(d.as_tuple()[2]) + 1)
+
         # Avoid conversion to scientific notation by accessing `sign`, `digits`
         # and `exponent` from `Decimal.as_tuple()` directly.
-        sign, digits, exponent = d.quantize(exp, ROUND_HALF_UP).as_tuple()
+        sign, digits, exponent = d.quantize(exp, ROUND_HALF_UP,
+                Context(prec=prec)).as_tuple()
+
         digits = [unicode(digit) for digit in reversed(digits)]
         while len(digits) <= abs(exponent):
             digits.append(u'0')

tests/regressiontests/defaultfilters/tests.py

@@ -1 +1 @@
 # -*- coding: utf-8 -*-
 import datetime
+import decimal
 from django.utils import unittest
 
 from django.template.defaultfilters import *
@@ -53 +54 @@
 
         self.assertEqual(floatformat(FloatWrapper(11.000001), -2), u'11.00')
 
+        decimal.getcontext().prec = 2
+        self.assertEqual(floatformat(1.2345, 2), u'1.23')
+        self.assertEqual(floatformat(15.2042, -3), u'15.204')
+
+
     # This fails because of Python's float handling. Floats with many zeroes
     # after the decimal point should be passed in as another type such as
     # unicode or Decimal.