Source code for falcon.routing.converters

# Copyright 2017 by Rackspace Hosting, Inc.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.

import abc
from datetime import datetime
import uuid

import six

__all__ = (

# PERF(kgriffs): Avoid an extra namespace lookup when using this function
strptime = datetime.strptime

[docs]class BaseConverter(object): """Abstract base class for URI template field converters.""" @abc.abstractmethod # pragma: no cover
[docs] def convert(self, value): """Convert a URI template field value to another format or type. Args: value (str): Original string to convert. Returns: object: Converted field value, or ``None`` if the field can not be converted. """
[docs]class IntConverter(BaseConverter): """Converts a field value to an int. Identifier: `int` Keyword Args: num_digits (int): Require the value to have the given number of digits. min (int): Reject the value if it is less than this number. max (int): Reject the value if it is greater than this number. """ __slots__ = ('_num_digits', '_min', '_max') def __init__(self, num_digits=None, min=None, max=None): if num_digits is not None and num_digits < 1: raise ValueError('num_digits must be at least 1') self._num_digits = num_digits self._min = min self._max = max def convert(self, value): if self._num_digits is not None and len(value) != self._num_digits: return None # NOTE(kgriffs): int() will accept numbers with preceding or # trailing whitespace, so we need to do our own check. Using # strip() is faster than either a regex or a series of or'd # membership checks via "in", esp. as the length of contiguous # numbers in the value grows. if value.strip() != value: return None try: value = int(value) except ValueError: return None if self._min is not None and value < self._min: return None if self._max is not None and value > self._max: return None return value
[docs]class DateTimeConverter(BaseConverter): """Converts a field value to a datetime. Identifier: `dt` Keyword Args: format_string (str): String used to parse the field value into a datetime. Any format recognized by strptime() is supported (default ``'%Y-%m-%dT%H:%M:%SZ'``). """ __slots__ = ('_format_string',) def __init__(self, format_string='%Y-%m-%dT%H:%M:%SZ'): self._format_string = format_string def convert(self, value): try: return strptime(value, self._format_string) except ValueError: return None
[docs]class UUIDConverter(BaseConverter): """Converts a field value to a uuid.UUID. Identifier: `uuid` In order to be converted, the field value must consist of a string of 32 hexadecimal digits, as defined in RFC 4122, Section 3. Note, however, that hyphens and the URN prefix are optional. """ def convert(self, value): try: return uuid.UUID(value) except ValueError: return None
BUILTIN = ( ('int', IntConverter), ('dt', DateTimeConverter), ('uuid', UUIDConverter), )