Ticket #11206: 11206-floatformat-r14785.diff

django/template/defaultfilters.py

@@ -170 +170 @@
     else:
         exp = Decimal('1.0') / (Decimal(10) ** abs(p))
     try:
-        return mark_safe(formats.number_format(u'%s' % str(d.quantize(exp, ROUND_HALF_UP)), abs(p)))
+        # 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()
+        digits = list(unicode(digit) for digit in reversed(digits))
+        while len(digits) <= abs(exponent):
+            digits.append('0')
+        digits.insert(-exponent, '.')
+        if sign:
+            digits.append('-')
+        number = ''.join(reversed(digits))
+        return mark_safe(formats.number_format(number, abs(p)))
     except InvalidOperation:
         return input_val
 floatformat.is_safe = True

tests/regressiontests/defaultfilters/tests.py

@@ -29 +29 @@
         self.assertEqual(floatformat(u'¿Cómo esta usted?'), u'')
         self.assertEqual(floatformat(None), u'')
 
+        # Check that we're not converting to scientific notation.
+        self.assertEqual(floatformat(0, 10), u'0.0000000000')
+        self.assertEqual(floatformat(0.000000000000000000015, 20),
+                                     u'0.00000000000000000002')
+
         pos_inf = float(1e30000)
         self.assertEqual(floatformat(pos_inf), unicode(pos_inf))
 
@@ -46 +51 @@
 
         self.assertEqual(floatformat(FloatWrapper(11.000001), -2), u'11.00')
 
+    # 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.
+    @unittest.expectedFailure
+    def test_floatformat_fail(self):
+        self.assertEqual(floatformat(1.00000000000000015, 16), u'1.0000000000000002')
+
     def test_addslashes(self):
         self.assertEqual(addslashes(u'"double quotes" and \'single quotes\''),
                           u'\\"double quotes\\" and \\\'single quotes\\\'')