openstack/deb-python-falcon
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da2bc234f86127b78a4256c9eb765dca32eae8d3
deb-python-falcon/falcon/response.py
Kurt Griffiths da2bc234f8 doc(reference): Standardize docstring syntax 
Unify the use of markup in docstrings, particulary relating to the use of
backticks and asterisks. Also clean up any remaining minor inconsistencies or
errors in the docstrings.

Closes #334
2015-02-03 18:45:52 -06:00

437 lines
16 KiB
Python
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# Copyright 2013 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
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import six
from falcon.response_helpers import header_property, format_range
from falcon.util import dt_to_http, uri
class Response(object):
"""Represents an HTTP response to a client request.
Note:
`Response` is not meant to be instantiated directly by responders.
Attributes:
status (str): HTTP status line (e.g., '200 OK'). Falcon requires the
full status line, not just the code (e.g., 200). This design
makes the framework more efficient because it does not have to
do any kind of conversion or lookup when composing the WSGI
response.
If not set explicitly, the status defaults to '200 OK'.
Note:
Falcon provides a number of constants for common status
codes. They all start with the ``HTTP_`` prefix, as in:
``falcon.HTTP_204``.
body (str or unicode): String representing response content. If
Unicode, Falcon will encode as UTF-8 in the response. If
data is already a byte string, use the data attribute
instead (it's faster).
body_encoded (bytes): Returns a UTF-8 encoded version of `body`.
data (bytes): Byte string representing response content.
Use this attribute in lieu of `body` when your content is
already a byte string (``str`` or ``bytes`` in Python 2, or
simply ``bytes`` in Python 3). See also the note below.
Note:
Under Python 2.x, if your content is of type ``str``, using
the `data` attribute instead of `body` is the most
efficient approach. However, if
your text is of type ``unicode``, you will need to use the
`body` attribute instead.
Under Python 3.x, on the other hand, the 2.x ``str`` type can
be thought of as
having been replaced by what was once the ``unicode`` type,
and so you will need to always use the `body` attribute for
strings to
ensure Unicode characters are properly encoded in the
HTTP response.
stream: Either a file-like object with a `read()` method that takes
an optional size argument and returns a block of bytes, or an
iterable object, representing response content, and yielding
blocks as byte strings. Falcon will use *wsgi.file_wrapper*, if
provided by the WSGI server, in order to efficiently serve
file-like objects.
stream_len (int): Expected length of `stream` (e.g., file size).
"""
__slots__ = (
'_body', # Stuff
'_body_encoded', # Stuff
'data',
'_headers',
'status',
'stream',
'stream_len'
)
def __init__(self):
self.status = '200 OK'
self._headers = {}
self._body = None
self._body_encoded = None
self.data = None
self.stream = None
self.stream_len = None
def _get_body(self):
return self._body
def _set_body(self, value):
self._body = value
self._body_encoded = None
# NOTE(flaper87): Lets use a property
# for the body in case its content was
# encoded and then modified.
body = property(_get_body, _set_body)
@property
def body_encoded(self):
# NOTE(flaper87): Notice this property
# is not thread-safe. If body is modified
# before this property returns, we might
# end up returning None.
body = self._body
if body and self._body_encoded is None:
# NOTE(flaper87): Assume it is an
# encoded str, then check and encode
# if it isn't.
self._body_encoded = body
if isinstance(body, six.text_type):
self._body_encoded = body.encode('utf-8')
return self._body_encoded
def set_stream(self, stream, stream_len):
"""Convenience method for setting both `stream` and `stream_len`.
Although the `stream` and `stream_len` properties may be set
directly, using this method ensures `stream_len` is not
accidentally neglected.
"""
self.stream = stream
self.stream_len = stream_len
def set_header(self, name, value):
"""Set a header for this response to a given value.
Warning:
Calling this method overwrites the existing value, if any.
Args:
name (str): Header name to set (case-insensitive). Must be of
type ``str`` or ``StringType``, and only character values 0x00
through 0xFF may be used on platforms that use wide
characters.
value (str): Value for the header. Must be of type ``str`` or
``StringType``, and only character values 0x00 through 0xFF
may be used on platforms that use wide characters.
"""
# NOTE(kgriffs): normalize name by lowercasing it
self._headers[name.lower()] = value
def append_header(self, name, value):
"""Set or append a header for this response.
Warning:
If the header already exists, the new value will be appended
to it, delimited by a comma. Most header specifications support
this format, Cookie and Set-Cookie being the notable exceptions.
Args:
name (str): Header name to set (case-insensitive). Must be of
type ``str`` or ``StringType``, and only character values 0x00
through 0xFF may be used on platforms that use wide
characters.
value (str): Value for the header. Must be of type ``str`` or
``StringType``, and only character values 0x00 through 0xFF
may be used on platforms that use wide characters.
"""
name = name.lower()
if name in self._headers:
value = self._headers[name] + ',' + value
self._headers[name] = value
def set_headers(self, headers):
"""Set several headers at once.
Warning:
Calling this method overwrites existing values, if any.
Args:
headers (dict or list): A dictionary of header names and values
to set, or ``list`` of (*name*, *value*) tuples. Both *name*
and *value* must be of type ``str`` or ``StringType``, and
only character values 0x00 through 0xFF may be used on
platforms that use wide characters.
Note:
Falcon can process a list of tuples slightly faster
than a dict.
Raises:
ValueError: `headers` was not a ``dict`` or ``list`` of ``tuple``.
"""
if isinstance(headers, dict):
headers = headers.items()
# NOTE(kgriffs): We can't use dict.update because we have to
# normalize the header names.
_headers = self._headers
for name, value in headers:
_headers[name.lower()] = value
def add_link(self, target, rel, title=None, title_star=None,
anchor=None, hreflang=None, type_hint=None):
"""
Add a link header to the response.
See also: https://tools.ietf.org/html/rfc5988
Note:
Calling this method repeatedly will cause each link to be
appended to the Link header value, separated by commas.
Note:
So-called "link-extension" elements, as defined by RFC 5988,
are not yet supported. See also Issue #288.
Args:
target (str): Target IRI for the resource identified by the
link. Will be converted to a URI, if necessary, per
RFC 3987, Section 3.1.
rel (str): Relation type of the link, such as "next" or
"bookmark". See also http://goo.gl/618GHr for a list
of registered link relation types.
Kwargs:
title (str): Human-readable label for the destination of
the link (default ``None``). If the title includes non-ASCII
characters, you will need to use `title_star` instead, or
provide both a US-ASCII version using `title` and a
Unicode version using `title_star`.
title_star (tuple of str): Localized title describing the
destination of the link (default ``None``). The value must be a
two-member tuple in the form of (*language-tag*, *text*),
where *language-tag* is a standard language identifier as
defined in RFC 5646, Section 2.1, and *text* is a Unicode
string.
Note:
*language-tag* may be an empty string, in which case the
client will assume the language from the general context
of the current request.
Note:
*text* will always be encoded as UTF-8. If the string
contains non-ASCII characters, it should be passed as
a ``unicode`` type string (requires the 'u' prefix in
Python 2).
anchor (str): Override the context IRI with a different URI
(default None). By default, the context IRI for the link is
simply the IRI of the requested resource. The value
provided may be a relative URI.
hreflang (str or iterable): Either a single *language-tag*, or
a ``list`` or ``tuple`` of such tags to provide a hint to the
client as to the language of the result of following the link.
A list of tags may be given in order to indicate to the
client that the target resource is available in multiple
languages.
type_hint(str): Provides a hint as to the media type of the
result of dereferencing the link (default ``None``). As noted
in RFC 5988, this is only a hint and does not override the
Content-Type header returned when the link is followed.
"""
# PERF(kgriffs): Heuristic to detect possiblity of an extension
# relation type, in which case it will be a URL that may contain
# reserved characters. Otherwise, don't waste time running the
# string through uri.encode
#
# Example values for rel:
#
# "next"
# "http://example.com/ext-type"
# "https://example.com/ext-type"
# "alternate http://example.com/ext-type"
# "http://example.com/ext-type alternate"
#
if '//' in rel:
if ' ' in rel:
rel = ('"' +
' '.join([uri.encode(r) for r in rel.split()]) +
'"')
else:
rel = '"' + uri.encode(rel) + '"'
value = '<' + uri.encode(target) + '>; rel=' + rel
if title is not None:
value += '; title="' + title + '"'
if title_star is not None:
value += ("; title*=UTF-8'" + title_star[0] + "'" +
uri.encode_value(title_star[1]))
if type_hint is not None:
value += '; type="' + type_hint + '"'
if hreflang is not None:
if isinstance(hreflang, six.string_types):
value += '; hreflang=' + hreflang
else:
value += '; '
value += '; '.join(['hreflang=' + lang for lang in hreflang])
if anchor is not None:
value += '; anchor="' + uri.encode(anchor) + '"'
_headers = self._headers
if 'link' in _headers:
_headers['link'] += ', ' + value
else:
_headers['link'] = value
cache_control = header_property(
'Cache-Control',
"""Sets the Cache-Control header.
Used to set a list of cache directives to use as the value of the
Cache-Control header. The list will be joined with ", " to produce
the value for the header.
""",
lambda v: ', '.join(v))
content_location = header_property(
'Content-Location',
'Sets the Content-Location header.',
uri.encode)
content_range = header_property(
'Content-Range',
"""A tuple to use in constructing a value for the Content-Range header.
The tuple has the form (*start*, *end*, *length*), where *start* and
*end* designate the byte range (inclusive), and *length* is the
total number of bytes, or '*' if unknown. You may pass ``int``'s for
these numbers (no need to convert to ``str`` beforehand).
Note:
You only need to use the alternate form, 'bytes */1234', for
responses that use the status '416 Range Not Satisfiable'. In this
case, raising ``falcon.HTTPRangeNotSatisfiable`` will do the right
thing.
See also: http://goo.gl/Iglhp
""",
format_range)
content_type = header_property(
'Content-Type',
'Sets the Content-Type header.')
etag = header_property(
'ETag',
'Sets the ETag header.')
last_modified = header_property(
'Last-Modified',
"""Sets the Last-Modified header. Set to a ``datetime`` (UTC) instance.
Note:
Falcon will format the ``datetime`` as an HTTP date string.
""",
dt_to_http)
location = header_property(
'Location',
'Sets the Location header.',
uri.encode)
retry_after = header_property(
'Retry-After',
"""Sets the Retry-After header.
The expected value is an integral number of seconds to use as the
value for the header. The HTTP-date syntax is not supported.
""",
str)
vary = header_property(
'Vary',
"""Value to use for the Vary header.
Set this property to an iterable of header names. For a single
asterisk or field value, simply pass a single-element ``list`` or
``tuple``.
"Tells downstream proxies how to match future request headers
to decide whether the cached response can be used rather than
requesting a fresh one from the origin server."
(Wikipedia)
See also: http://goo.gl/NGHdL
""",
lambda v: ', '.join(v))
def _wsgi_headers(self, media_type=None):
"""Convert headers into the format expected by WSGI servers.
Args:
media_type: Default media type to use for the Content-Type
header if the header was not set explicitly (default ``None``).
"""
headers = self._headers
# PERF(kgriffs): Using "in" like this is faster than using
# dict.setdefault (tested on py27).
set_content_type = (media_type is not None and
'content-type' not in headers)
if set_content_type:
headers['content-type'] = media_type
if six.PY2: # pragma: no cover
# PERF(kgriffs): Don't create an extra list object if
# it isn't needed.
return headers.items()
return list(headers.items()) # pragma: no cover
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