525 lines
17 KiB
Plaintext
525 lines
17 KiB
Plaintext
============
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Django Utils
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============
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.. module:: django.utils
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:synopsis: Django's built-in utilities.
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This document covers all stable modules in ``django.utils``. Most of the
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modules in ``django.utils`` are designed for internal use and only the
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following parts can be considered stable and thus backwards compatible as per
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the :ref:`internal release deprecation policy <internal-release-deprecation-policy>`.
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``django.utils.cache``
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======================
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.. module:: django.utils.cache
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:synopsis: Helper functions for controlling caching.
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This module contains helper functions for controlling caching. It does so by
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managing the ``Vary`` header of responses. It includes functions to patch the
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header of response objects directly and decorators that change functions to do
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that header-patching themselves.
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For information on the ``Vary`` header, see `RFC 2616 section 14.44`_.
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.. _RFC 2616 section 14.44: http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.44
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Essentially, the ``Vary`` HTTP header defines which headers a cache should take
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into account when building its cache key. Requests with the same path but
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different header content for headers named in ``Vary`` need to get different
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cache keys to prevent delivery of wrong content.
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For example, :doc:`internationalization </topics/i18n/index>` middleware would need
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to distinguish caches by the ``Accept-language`` header.
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.. function:: patch_cache_control(response, **kwargs)
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This function patches the ``Cache-Control`` header by adding all keyword
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arguments to it. The transformation is as follows:
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* All keyword parameter names are turned to lowercase, and underscores
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are converted to hyphens.
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* If the value of a parameter is ``True`` (exactly ``True``, not just a
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true value), only the parameter name is added to the header.
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* All other parameters are added with their value, after applying
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``str()`` to it.
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.. function:: get_max_age(response)
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Returns the max-age from the response Cache-Control header as an integer
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(or ``None`` if it wasn't found or wasn't an integer).
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.. function:: patch_response_headers(response, cache_timeout=None)
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Adds some useful headers to the given ``HttpResponse`` object:
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* ``ETag``
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* ``Last-Modified``
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* ``Expires``
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* ``Cache-Control``
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Each header is only added if it isn't already set.
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``cache_timeout`` is in seconds. The :setting:`CACHE_MIDDLEWARE_SECONDS`
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setting is used by default.
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.. function:: add_never_cache_headers(response)
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Adds headers to a response to indicate that a page should never be cached.
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.. function:: patch_vary_headers(response, newheaders)
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Adds (or updates) the ``Vary`` header in the given ``HttpResponse`` object.
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``newheaders`` is a list of header names that should be in ``Vary``.
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Existing headers in ``Vary`` aren't removed.
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.. function:: get_cache_key(request, key_prefix=None)
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Returns a cache key based on the request path. It can be used in the
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request phase because it pulls the list of headers to take into account
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from the global path registry and uses those to build a cache key to
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check against.
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If there is no headerlist stored, the page needs to be rebuilt, so this
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function returns ``None``.
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.. function:: learn_cache_key(request, response, cache_timeout=None, key_prefix=None)
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Learns what headers to take into account for some request path from the
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response object. It stores those headers in a global path registry so that
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later access to that path will know what headers to take into account
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without building the response object itself. The headers are named in
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the ``Vary`` header of the response, but we want to prevent response
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generation.
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The list of headers to use for cache key generation is stored in the same
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cache as the pages themselves. If the cache ages some data out of the
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cache, this just means that we have to build the response once to get at
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the Vary header and so at the list of headers to use for the cache key.
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``django.utils.datastructures``
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===============================
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.. module:: django.utils.datastructures
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:synopsis: Data structures that aren't in Python's standard library.
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.. class:: SortedDict
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The :class:`django.utils.datastructures.SortedDict` class is a dictionary
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that keeps its keys in the order in which they're inserted.
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``SortedDict`` adds two additional methods to the standard Python ``dict``
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class:
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.. method:: insert(index, key, value)
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Inserts the key, value pair before the item with the given index.
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.. method:: value_for_index(index)
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Returns the value of the item at the given zero-based index.
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Creating a new SortedDict
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-------------------------
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Creating a new ``SortedDict`` must be done in a way where ordering is
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guaranteed. For example::
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SortedDict({'b': 1, 'a': 2, 'c': 3})
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will not work. Passing in a basic Python ``dict`` could produce unreliable
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results. Instead do::
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SortedDict([('b', 1), ('a', 2), ('c', 3)])
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``django.utils.encoding``
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=========================
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.. module:: django.utils.encoding
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:synopsis: A series of helper classes and function to manage character encoding.
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.. class:: StrAndUnicode
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A class whose ``__str__`` returns its ``__unicode__`` as a UTF-8
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bytestring. Useful as a mix-in.
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.. function:: smart_unicode(s, encoding='utf-8', strings_only=False, errors='strict')
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Returns a ``unicode`` object representing ``s``. Treats bytestrings using
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the 'encoding' codec.
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If ``strings_only`` is ``True``, don't convert (some) non-string-like
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objects.
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.. function:: is_protected_type(obj)
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Determine if the object instance is of a protected type.
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Objects of protected types are preserved as-is when passed to
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``force_unicode(strings_only=True)``.
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.. function:: force_unicode(s, encoding='utf-8', strings_only=False, errors='strict')
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Similar to ``smart_unicode``, except that lazy instances are resolved to
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strings, rather than kept as lazy objects.
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If ``strings_only`` is ``True``, don't convert (some) non-string-like
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objects.
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.. function:: smart_str(s, encoding='utf-8', strings_only=False, errors='strict')
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Returns a bytestring version of ``s``, encoded as specified in
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``encoding``.
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If ``strings_only`` is ``True``, don't convert (some) non-string-like
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objects.
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.. function:: iri_to_uri(iri)
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Convert an Internationalized Resource Identifier (IRI) portion to a URI
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portion that is suitable for inclusion in a URL.
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This is the algorithm from section 3.1 of `RFC 3987`_. However, since we
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are assuming input is either UTF-8 or unicode already, we can simplify
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things a little from the full method.
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.. _RFC 3987: http://www.ietf.org/rfc/rfc3987.txt
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Returns an ASCII string containing the encoded result.
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``django.utils.feedgenerator``
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==============================
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.. module:: django.utils.feedgenerator
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:synopsis: Syndication feed generation library -- used for generating RSS, etc.
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Sample usage::
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>>> from django.utils import feedgenerator
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>>> feed = feedgenerator.Rss201rev2Feed(
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... title=u"Poynter E-Media Tidbits",
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... link=u"http://www.poynter.org/column.asp?id=31",
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... description=u"A group Weblog by the sharpest minds in online media/journalism/publishing.",
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... language=u"en",
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... )
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>>> feed.add_item(
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... title="Hello",
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... link=u"http://www.holovaty.com/test/",
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... description="Testing."
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... )
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>>> fp = open('test.rss', 'w')
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>>> feed.write(fp, 'utf-8')
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>>> fp.close()
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For simplifying the selection of a generator use ``feedgenerator.DefaultFeed``
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which is currently ``Rss201rev2Feed``
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For definitions of the different versions of RSS, see:
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http://diveintomark.org/archives/2004/02/04/incompatible-rss
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.. function:: get_tag_uri(url, date)
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Creates a TagURI.
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See http://diveintomark.org/archives/2004/05/28/howto-atom-id
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SyndicationFeed
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---------------
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.. class:: SyndicationFeed
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Base class for all syndication feeds. Subclasses should provide write().
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.. method:: __init__(title, link, description, [language=None, author_email=None, author_name=None, author_link=None, subtitle=None, categories=None, feed_url=None, feed_copyright=None, feed_guid=None, ttl=None, **kwargs])
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Initialize the feed with the given dictionary of metadata, which applies
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to the entire feed.
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Any extra keyword arguments you pass to ``__init__`` will be stored in
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``self.feed``.
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All parameters should be Unicode objects, except ``categories``, which
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should be a sequence of Unicode objects.
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.. method:: add_item(title, link, description, [author_email=None, author_name=None, author_link=None, pubdate=None, comments=None, unique_id=None, enclosure=None, categories=(), item_copyright=None, ttl=None, **kwargs])
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Adds an item to the feed. All args are expected to be Python ``unicode``
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objects except ``pubdate``, which is a ``datetime.datetime`` object, and
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``enclosure``, which is an instance of the ``Enclosure`` class.
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.. method:: num_items()
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.. method:: root_attributes()
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Return extra attributes to place on the root (i.e. feed/channel)
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element. Called from ``write()``.
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.. method:: add_root_elements(handler)
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Add elements in the root (i.e. feed/channel) element.
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Called from ``write()``.
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.. method:: item_attributes(item)
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Return extra attributes to place on each item (i.e. item/entry)
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element.
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.. method:: add_item_elements(handler, item)
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Add elements on each item (i.e. item/entry) element.
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.. method:: write(outfile, encoding)
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Outputs the feed in the given encoding to ``outfile``, which is a
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file-like object. Subclasses should override this.
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.. method:: writeString(encoding)
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Returns the feed in the given encoding as a string.
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.. method:: latest_post_date()
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Returns the latest item's ``pubdate``. If none of them have a
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``pubdate``, this returns the current date/time.
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Enclosure
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---------
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.. class:: Enclosure
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Represents an RSS enclosure
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RssFeed
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-------
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.. class:: RssFeed(SyndicationFeed)
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Rss201rev2Feed
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--------------
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.. class:: Rss201rev2Feed(RssFeed)
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Spec: http://blogs.law.harvard.edu/tech/rss
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RssUserland091Feed
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------------------
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.. class:: RssUserland091Feed(RssFeed)
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Spec: http://backend.userland.com/rss091
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Atom1Feed
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---------
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.. class:: Atom1Feed(SyndicationFeed)
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Spec: http://atompub.org/2005/07/11/draft-ietf-atompub-format-10.html
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``django.utils.http``
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=====================
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.. module:: django.utils.http
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:synopsis: HTTP helper functions. (URL encoding, cookie handling, ...)
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.. function:: urlquote(url, safe='/')
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A version of Python's ``urllib.quote()`` function that can operate on
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unicode strings. The url is first UTF-8 encoded before quoting. The
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returned string can safely be used as part of an argument to a subsequent
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``iri_to_uri()`` call without double-quoting occurring. Employs lazy
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execution.
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.. function:: urlquote_plus(url, safe='')
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A version of Python's urllib.quote_plus() function that can operate on
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unicode strings. The url is first UTF-8 encoded before quoting. The
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returned string can safely be used as part of an argument to a subsequent
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``iri_to_uri()`` call without double-quoting occurring. Employs lazy
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execution.
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.. function:: urlencode(query, doseq=0)
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A version of Python's urllib.urlencode() function that can operate on
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unicode strings. The parameters are first case to UTF-8 encoded strings
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and then encoded as per normal.
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.. function:: cookie_date(epoch_seconds=None)
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Formats the time to ensure compatibility with Netscape's cookie standard.
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Accepts a floating point number expressed in seconds since the epoch in
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UTC--such as that outputted by ``time.time()``. If set to ``None``,
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defaults to the current time.
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Outputs a string in the format ``Wdy, DD-Mon-YYYY HH:MM:SS GMT``.
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.. function:: http_date(epoch_seconds=None)
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Formats the time to match the RFC 1123 date format as specified by HTTP
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`RFC 2616`_ section 3.3.1.
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.. _RFC 2616: http://www.w3.org/Protocols/rfc2616/rfc2616.txt
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Accepts a floating point number expressed in seconds since the epoch in
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UTC--such as that outputted by ``time.time()``. If set to ``None``,
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defaults to the current time.
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Outputs a string in the format ``Wdy, DD Mon YYYY HH:MM:SS GMT``.
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.. function:: base36_to_int(s)
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Converts a base 36 string to an integer.
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.. function:: int_to_base36(i)
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Converts an integer to a base 36 string.
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``django.utils.safestring``
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===========================
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.. module:: django.utils.safestring
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:synopsis: Functions and classes for working with strings that can be displayed safely without further escaping in HTML.
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Functions and classes for working with "safe strings": strings that can be
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displayed safely without further escaping in HTML. Marking something as a "safe
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string" means that the producer of the string has already turned characters
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that should not be interpreted by the HTML engine (e.g. '<') into the
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appropriate entities.
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.. class:: SafeString
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A string subclass that has been specifically marked as "safe" (requires no
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further escaping) for HTML output purposes.
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.. class:: SafeUnicode
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A unicode subclass that has been specifically marked as "safe" for HTML
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output purposes.
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.. function:: mark_safe(s)
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Explicitly mark a string as safe for (HTML) output purposes. The returned
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object can be used everywhere a string or unicode object is appropriate.
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Can be called multiple times on a single string.
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.. function:: mark_for_escaping(s)
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Explicitly mark a string as requiring HTML escaping upon output. Has no
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effect on ``SafeData`` subclasses.
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Can be called multiple times on a single string (the resulting escaping is
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only applied once).
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``django.utils.translation``
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============================
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.. module:: django.utils.translation
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:synopsis: Internationalization support.
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For a complete discussion on the usage of the following see the
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:doc:`Internationalization documentation </topics/i18n/internationalization>`.
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.. function:: gettext(message)
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Translates ``message`` and returns it in a UTF-8 bytestring
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.. function:: ugettext(message)
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Translates ``message`` and returns it in a unicode string
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.. function:: gettext_lazy(message)
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.. function:: ugettext_lazy(message)
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Same as the non-lazy versions above, but using lazy execution.
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See :ref:`lazy translations documentation <lazy-translations>`.
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.. function:: gettext_noop(message)
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Marks strings for translation but doesn't translate them now. This can be
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used to store strings in global variables that should stay in the base
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language (because they might be used externally) and will be translated
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later.
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.. function:: ngettext(singular, plural, number)
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Translates ``singular`` and ``plural`` and returns the appropriate string
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based on ``number`` in a UTF-8 bytestring.
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.. function:: ungettext(singular, plural, number)
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Translates ``singular`` and ``plural`` and returns the appropriate string
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based on ``number`` in a unicode string.
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.. function:: ngettext_lazy(singular, plural, number)
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.. function:: ungettext_lazy(singular, plural, number)
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Same as the non-lazy versions above, but using lazy execution.
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See :ref:`lazy translations documentation <lazy-translations>`.
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.. function:: string_concat(*strings)
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Lazy variant of string concatenation, needed for translations that are
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constructed from multiple parts.
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.. function:: activate(language)
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Fetches the translation object for a given tuple of application name and
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language and installs it as the current translation object for the current
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thread.
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.. function:: deactivate()
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De-installs the currently active translation object so that further _ calls
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will resolve against the default translation object, again.
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.. function:: deactivate_all()
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Makes the active translation object a NullTranslations() instance. This is
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useful when we want delayed translations to appear as the original string
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for some reason.
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.. function:: get_language()
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Returns the currently selected language code.
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.. function:: get_language_bidi()
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Returns selected language's BiDi layout:
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* ``False`` = left-to-right layout
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* ``True`` = right-to-left layout
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.. function:: get_language_from_request(request)
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Analyzes the request to find what language the user wants the system to show.
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Only languages listed in settings.LANGUAGES are taken into account. If the user
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requests a sublanguage where we have a main language, we send out the main
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language.
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.. function:: to_locale(language)
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Turns a language name (en-us) into a locale name (en_US).
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.. function:: templatize(src)
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Turns a Django template into something that is understood by xgettext. It does
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so by translating the Django translation tags into standard gettext function
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invocations.
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``django.utils.tzinfo``
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=======================
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.. module:: django.utils.tzinfo
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:synopsis: Implementation of ``tzinfo`` classes for use with ``datetime.datetime``.
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.. class:: FixedOffset
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Fixed offset in minutes east from UTC.
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.. class:: LocalTimezone
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Proxy timezone information from time module.
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