Add DecimalField support

1 files changed, 75 insertions, 0 deletions

diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index f3496b53..a1b9f546 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -2,6 +2,7 @@ from __future__ import unicode_literals
 
 import copy
 import datetime
+from decimal import Decimal, DecimalException
 import inspect
 import re
 import warnings
@@ -721,6 +722,80 @@ class FloatField(WritableField):
             raise ValidationError(msg)
 
 
+class DecimalField(WritableField):
+    type_name = 'DecimalField'
+    form_field_class = forms.DecimalField
+
+    default_error_messages = {
+        'invalid': _('Enter a number.'),
+        'max_value': _('Ensure this value is less than or equal to %(limit_value)s.'),
+        'min_value': _('Ensure this value is greater than or equal to %(limit_value)s.'),
+        'max_digits': _('Ensure that there are no more than %s digits in total.'),
+        'max_decimal_places': _('Ensure that there are no more than %s decimal places.'),
+        'max_whole_digits': _('Ensure that there are no more than %s digits before the decimal point.')
+    }
+
+    def __init__(self, max_value=None, min_value=None, max_digits=None, decimal_places=None, *args, **kwargs):
+        self.max_value, self.min_value = max_value, min_value
+        self.max_digits, self.decimal_places = max_digits, decimal_places
+        super(DecimalField, self).__init__(self, *args, **kwargs)
+
+        if max_value is not None:
+            self.validators.append(validators.MaxValueValidator(max_value))
+        if min_value is not None:
+            self.validators.append(validators.MinValueValidator(min_value))
+
+    def from_native(self, value):
+        """
+        Validates that the input is a decimal number. Returns a Decimal
+        instance. Returns None for empty values. Ensures that there are no more
+        than max_digits in the number, and no more than decimal_places digits
+        after the decimal point.
+        """
+        if value in validators.EMPTY_VALUES:
+            return None
+        value = smart_text(value).strip()
+        try:
+            value = Decimal(value)
+        except DecimalException:
+            raise ValidationError(self.error_messages['invalid'])
+        return value
+
+    def to_native(self, value):
+        if value is not None:
+            return str(value)
+        return value
+
+    def validate(self, value):
+        super(DecimalField, self).validate(value)
+        if value in validators.EMPTY_VALUES:
+            return
+        # Check for NaN, Inf and -Inf values. We can't compare directly for NaN,
+        # since it is never equal to itself. However, NaN is the only value that
+        # isn't equal to itself, so we can use this to identify NaN
+        if value != value or value == Decimal("Inf") or value == Decimal("-Inf"):
+            raise ValidationError(self.error_messages['invalid'])
+        sign, digittuple, exponent = value.as_tuple()
+        decimals = abs(exponent)
+        # digittuple doesn't include any leading zeros.
+        digits = len(digittuple)
+        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
+        whole_digits = digits - decimals
+
+        if self.max_digits is not None and digits > self.max_digits:
+            raise ValidationError(self.error_messages['max_digits'] % self.max_digits)
+        if self.decimal_places is not None and decimals > self.decimal_places:
+            raise ValidationError(self.error_messages['max_decimal_places'] % self.decimal_places)
+        if self.max_digits is not None and self.decimal_places is not None and whole_digits > (self.max_digits - self.decimal_places):
+            raise ValidationError(self.error_messages['max_whole_digits'] % (self.max_digits - self.decimal_places))
+        return value
+
+
 class FileField(WritableField):
     use_files = True
     type_name = 'FileField'