fields.py 文件源码

def to_internal_value(self, data):
        """
        Validate that the input is a decimal number and return a Decimal
        instance.
        """
        data = smart_text(data).strip()
        if len(data) > self.MAX_STRING_LENGTH:
            self.fail('max_string_length')

        try:
            value = decimal.Decimal(data)
        except decimal.DecimalException:
            self.fail('invalid')

        # Check for NaN. It is the only value that isn't equal to itself,
        # so we can use this to identify NaN values.
        if value != value:
            self.fail('invalid')

        # Check for infinity and negative infinity.
        if value in (decimal.Decimal('Inf'), decimal.Decimal('-Inf')):
            self.fail('invalid')

        return self.validate_precision(value)