mirror of https://github.com/python/cpython
1515 lines
54 KiB
ReStructuredText
1515 lines
54 KiB
ReStructuredText
:mod:`!urllib.request` --- Extensible library for opening URLs
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==============================================================
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.. module:: urllib.request
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:synopsis: Extensible library for opening URLs.
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.. moduleauthor:: Jeremy Hylton <jeremy@alum.mit.edu>
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.. sectionauthor:: Moshe Zadka <moshez@users.sourceforge.net>
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.. sectionauthor:: Senthil Kumaran <senthil@uthcode.com>
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**Source code:** :source:`Lib/urllib/request.py`
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--------------
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The :mod:`urllib.request` module defines functions and classes which help in
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opening URLs (mostly HTTP) in a complex world --- basic and digest
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authentication, redirections, cookies and more.
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.. seealso::
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The `Requests package <https://requests.readthedocs.io/en/master/>`_
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is recommended for a higher-level HTTP client interface.
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.. warning::
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On macOS it is unsafe to use this module in programs using
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:func:`os.fork` because the :func:`getproxies` implementation for
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macOS uses a higher-level system API. Set the environment variable
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``no_proxy`` to ``*`` to avoid this problem
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(e.g. ``os.environ["no_proxy"] = "*"``).
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.. include:: ../includes/wasm-notavail.rst
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The :mod:`urllib.request` module defines the following functions:
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.. function:: urlopen(url, data=None[, timeout], *, context=None)
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Open *url*, which can be either a string containing a valid, properly
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encoded URL, or a :class:`Request` object.
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*data* must be an object specifying additional data to be sent to the
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server, or ``None`` if no such data is needed. See :class:`Request`
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for details.
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urllib.request module uses HTTP/1.1 and includes ``Connection:close`` header
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in its HTTP requests.
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The optional *timeout* parameter specifies a timeout in seconds for
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blocking operations like the connection attempt (if not specified,
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the global default timeout setting will be used). This actually
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only works for HTTP, HTTPS and FTP connections.
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If *context* is specified, it must be a :class:`ssl.SSLContext` instance
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describing the various SSL options. See :class:`~http.client.HTTPSConnection`
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for more details.
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This function always returns an object which can work as a
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:term:`context manager` and has the properties *url*, *headers*, and *status*.
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See :class:`urllib.response.addinfourl` for more detail on these properties.
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For HTTP and HTTPS URLs, this function returns a
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:class:`http.client.HTTPResponse` object slightly modified. In addition
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to the three new methods above, the msg attribute contains the
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same information as the :attr:`~http.client.HTTPResponse.reason`
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attribute --- the reason phrase returned by server --- instead of
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the response headers as it is specified in the documentation for
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:class:`~http.client.HTTPResponse`.
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For FTP, file, and data URLs, this function
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returns a :class:`urllib.response.addinfourl` object.
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Raises :exc:`~urllib.error.URLError` on protocol errors.
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Note that ``None`` may be returned if no handler handles the request (though
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the default installed global :class:`OpenerDirector` uses
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:class:`UnknownHandler` to ensure this never happens).
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In addition, if proxy settings are detected (for example, when a ``*_proxy``
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environment variable like :envvar:`!http_proxy` is set),
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:class:`ProxyHandler` is default installed and makes sure the requests are
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handled through the proxy.
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The legacy ``urllib.urlopen`` function from Python 2.6 and earlier has been
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discontinued; :func:`urllib.request.urlopen` corresponds to the old
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``urllib2.urlopen``. Proxy handling, which was done by passing a dictionary
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parameter to ``urllib.urlopen``, can be obtained by using
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:class:`ProxyHandler` objects.
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.. audit-event:: urllib.Request fullurl,data,headers,method urllib.request.urlopen
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The default opener raises an :ref:`auditing event <auditing>`
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``urllib.Request`` with arguments ``fullurl``, ``data``, ``headers``,
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``method`` taken from the request object.
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.. versionchanged:: 3.2
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*cafile* and *capath* were added.
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HTTPS virtual hosts are now supported if possible (that is, if
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:const:`ssl.HAS_SNI` is true).
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*data* can be an iterable object.
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.. versionchanged:: 3.3
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*cadefault* was added.
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.. versionchanged:: 3.4.3
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*context* was added.
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.. versionchanged:: 3.10
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HTTPS connection now send an ALPN extension with protocol indicator
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``http/1.1`` when no *context* is given. Custom *context* should set
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ALPN protocols with :meth:`~ssl.SSLContext.set_alpn_protocols`.
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.. versionchanged:: 3.13
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Remove *cafile*, *capath* and *cadefault* parameters: use the *context*
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parameter instead.
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.. function:: install_opener(opener)
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Install an :class:`OpenerDirector` instance as the default global opener.
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Installing an opener is only necessary if you want urlopen to use that
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opener; otherwise, simply call :meth:`OpenerDirector.open` instead of
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:func:`~urllib.request.urlopen`. The code does not check for a real
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:class:`OpenerDirector`, and any class with the appropriate interface will
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work.
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.. function:: build_opener([handler, ...])
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Return an :class:`OpenerDirector` instance, which chains the handlers in the
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order given. *handler*\s can be either instances of :class:`BaseHandler`, or
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subclasses of :class:`BaseHandler` (in which case it must be possible to call
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the constructor without any parameters). Instances of the following classes
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will be in front of the *handler*\s, unless the *handler*\s contain them,
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instances of them or subclasses of them: :class:`ProxyHandler` (if proxy
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settings are detected), :class:`UnknownHandler`, :class:`HTTPHandler`,
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:class:`HTTPDefaultErrorHandler`, :class:`HTTPRedirectHandler`,
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:class:`FTPHandler`, :class:`FileHandler`, :class:`HTTPErrorProcessor`.
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If the Python installation has SSL support (i.e., if the :mod:`ssl` module
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can be imported), :class:`HTTPSHandler` will also be added.
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A :class:`BaseHandler` subclass may also change its :attr:`handler_order`
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attribute to modify its position in the handlers list.
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.. function:: pathname2url(path)
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Convert the pathname *path* from the local syntax for a path to the form used in
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the path component of a URL. This does not produce a complete URL. The return
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value will already be quoted using the :func:`~urllib.parse.quote` function.
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.. function:: url2pathname(path)
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Convert the path component *path* from a percent-encoded URL to the local syntax for a
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path. This does not accept a complete URL. This function uses
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:func:`~urllib.parse.unquote` to decode *path*.
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.. function:: getproxies()
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This helper function returns a dictionary of scheme to proxy server URL
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mappings. It scans the environment for variables named ``<scheme>_proxy``,
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in a case insensitive approach, for all operating systems first, and when it
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cannot find it, looks for proxy information from System
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Configuration for macOS and Windows Systems Registry for Windows.
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If both lowercase and uppercase environment variables exist (and disagree),
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lowercase is preferred.
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.. note::
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If the environment variable ``REQUEST_METHOD`` is set, which usually
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indicates your script is running in a CGI environment, the environment
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variable ``HTTP_PROXY`` (uppercase ``_PROXY``) will be ignored. This is
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because that variable can be injected by a client using the "Proxy:" HTTP
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header. If you need to use an HTTP proxy in a CGI environment, either use
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``ProxyHandler`` explicitly, or make sure the variable name is in
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lowercase (or at least the ``_proxy`` suffix).
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The following classes are provided:
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.. class:: Request(url, data=None, headers={}, origin_req_host=None, unverifiable=False, method=None)
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This class is an abstraction of a URL request.
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*url* should be a string containing a valid, properly encoded URL.
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*data* must be an object specifying additional data to send to the
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server, or ``None`` if no such data is needed. Currently HTTP
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requests are the only ones that use *data*. The supported object
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types include bytes, file-like objects, and iterables of bytes-like objects.
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If no ``Content-Length`` nor ``Transfer-Encoding`` header field
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has been provided, :class:`HTTPHandler` will set these headers according
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to the type of *data*. ``Content-Length`` will be used to send
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bytes objects, while ``Transfer-Encoding: chunked`` as specified in
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:rfc:`7230`, Section 3.3.1 will be used to send files and other iterables.
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For an HTTP POST request method, *data* should be a buffer in the
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standard :mimetype:`application/x-www-form-urlencoded` format. The
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:func:`urllib.parse.urlencode` function takes a mapping or sequence
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of 2-tuples and returns an ASCII string in this format. It should
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be encoded to bytes before being used as the *data* parameter.
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*headers* should be a dictionary, and will be treated as if
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:meth:`add_header` was called with each key and value as arguments.
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This is often used to "spoof" the ``User-Agent`` header value, which is
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used by a browser to identify itself -- some HTTP servers only
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allow requests coming from common browsers as opposed to scripts.
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For example, Mozilla Firefox may identify itself as ``"Mozilla/5.0
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(X11; U; Linux i686) Gecko/20071127 Firefox/2.0.0.11"``, while
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:mod:`urllib`'s default user agent string is
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``"Python-urllib/2.6"`` (on Python 2.6).
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All header keys are sent in camel case.
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An appropriate ``Content-Type`` header should be included if the *data*
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argument is present. If this header has not been provided and *data*
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is not ``None``, ``Content-Type: application/x-www-form-urlencoded`` will
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be added as a default.
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The next two arguments are only of interest for correct handling
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of third-party HTTP cookies:
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*origin_req_host* should be the request-host of the origin
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transaction, as defined by :rfc:`2965`. It defaults to
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``http.cookiejar.request_host(self)``. This is the host name or IP
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address of the original request that was initiated by the user.
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For example, if the request is for an image in an HTML document,
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this should be the request-host of the request for the page
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containing the image.
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*unverifiable* should indicate whether the request is unverifiable,
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as defined by :rfc:`2965`. It defaults to ``False``. An unverifiable
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request is one whose URL the user did not have the option to
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approve. For example, if the request is for an image in an HTML
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document, and the user had no option to approve the automatic
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fetching of the image, this should be true.
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*method* should be a string that indicates the HTTP request method that
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will be used (e.g. ``'HEAD'``). If provided, its value is stored in the
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:attr:`~Request.method` attribute and is used by :meth:`get_method`.
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The default is ``'GET'`` if *data* is ``None`` or ``'POST'`` otherwise.
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Subclasses may indicate a different default method by setting the
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:attr:`~Request.method` attribute in the class itself.
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.. note::
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The request will not work as expected if the data object is unable
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to deliver its content more than once (e.g. a file or an iterable
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that can produce the content only once) and the request is retried
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for HTTP redirects or authentication. The *data* is sent to the
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HTTP server right away after the headers. There is no support for
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a 100-continue expectation in the library.
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.. versionchanged:: 3.3
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:attr:`Request.method` argument is added to the Request class.
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.. versionchanged:: 3.4
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Default :attr:`Request.method` may be indicated at the class level.
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.. versionchanged:: 3.6
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Do not raise an error if the ``Content-Length`` has not been
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provided and *data* is neither ``None`` nor a bytes object.
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Fall back to use chunked transfer encoding instead.
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.. class:: OpenerDirector()
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The :class:`OpenerDirector` class opens URLs via :class:`BaseHandler`\ s chained
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together. It manages the chaining of handlers, and recovery from errors.
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.. class:: BaseHandler()
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This is the base class for all registered handlers --- and handles only the
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simple mechanics of registration.
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.. class:: HTTPDefaultErrorHandler()
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A class which defines a default handler for HTTP error responses; all responses
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are turned into :exc:`~urllib.error.HTTPError` exceptions.
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.. class:: HTTPRedirectHandler()
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A class to handle redirections.
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.. class:: HTTPCookieProcessor(cookiejar=None)
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A class to handle HTTP Cookies.
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.. class:: ProxyHandler(proxies=None)
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Cause requests to go through a proxy. If *proxies* is given, it must be a
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dictionary mapping protocol names to URLs of proxies. The default is to read
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the list of proxies from the environment variables
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``<protocol>_proxy``. If no proxy environment variables are set, then
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in a Windows environment proxy settings are obtained from the registry's
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Internet Settings section, and in a macOS environment proxy information
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is retrieved from the System Configuration Framework.
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To disable autodetected proxy pass an empty dictionary.
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The :envvar:`no_proxy` environment variable can be used to specify hosts
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which shouldn't be reached via proxy; if set, it should be a comma-separated
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list of hostname suffixes, optionally with ``:port`` appended, for example
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``cern.ch,ncsa.uiuc.edu,some.host:8080``.
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.. note::
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``HTTP_PROXY`` will be ignored if a variable ``REQUEST_METHOD`` is set;
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see the documentation on :func:`~urllib.request.getproxies`.
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.. class:: HTTPPasswordMgr()
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Keep a database of ``(realm, uri) -> (user, password)`` mappings.
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.. class:: HTTPPasswordMgrWithDefaultRealm()
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Keep a database of ``(realm, uri) -> (user, password)`` mappings. A realm of
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``None`` is considered a catch-all realm, which is searched if no other realm
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fits.
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.. class:: HTTPPasswordMgrWithPriorAuth()
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A variant of :class:`HTTPPasswordMgrWithDefaultRealm` that also has a
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database of ``uri -> is_authenticated`` mappings. Can be used by a
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BasicAuth handler to determine when to send authentication credentials
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immediately instead of waiting for a ``401`` response first.
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.. versionadded:: 3.5
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.. class:: AbstractBasicAuthHandler(password_mgr=None)
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This is a mixin class that helps with HTTP authentication, both to the remote
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host and to a proxy. *password_mgr*, if given, should be something that is
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compatible with :class:`HTTPPasswordMgr`; refer to section
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:ref:`http-password-mgr` for information on the interface that must be
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supported. If *passwd_mgr* also provides ``is_authenticated`` and
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``update_authenticated`` methods (see
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:ref:`http-password-mgr-with-prior-auth`), then the handler will use the
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``is_authenticated`` result for a given URI to determine whether or not to
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send authentication credentials with the request. If ``is_authenticated``
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returns ``True`` for the URI, credentials are sent. If ``is_authenticated``
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is ``False``, credentials are not sent, and then if a ``401`` response is
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received the request is re-sent with the authentication credentials. If
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authentication succeeds, ``update_authenticated`` is called to set
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``is_authenticated`` ``True`` for the URI, so that subsequent requests to
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the URI or any of its super-URIs will automatically include the
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authentication credentials.
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.. versionadded:: 3.5
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Added ``is_authenticated`` support.
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.. class:: HTTPBasicAuthHandler(password_mgr=None)
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Handle authentication with the remote host. *password_mgr*, if given, should
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be something that is compatible with :class:`HTTPPasswordMgr`; refer to
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section :ref:`http-password-mgr` for information on the interface that must
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be supported. HTTPBasicAuthHandler will raise a :exc:`ValueError` when
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presented with a wrong Authentication scheme.
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.. class:: ProxyBasicAuthHandler(password_mgr=None)
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Handle authentication with the proxy. *password_mgr*, if given, should be
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something that is compatible with :class:`HTTPPasswordMgr`; refer to section
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:ref:`http-password-mgr` for information on the interface that must be
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supported.
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.. class:: AbstractDigestAuthHandler(password_mgr=None)
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This is a mixin class that helps with HTTP authentication, both to the remote
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host and to a proxy. *password_mgr*, if given, should be something that is
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compatible with :class:`HTTPPasswordMgr`; refer to section
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:ref:`http-password-mgr` for information on the interface that must be
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supported.
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.. class:: HTTPDigestAuthHandler(password_mgr=None)
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Handle authentication with the remote host. *password_mgr*, if given, should
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be something that is compatible with :class:`HTTPPasswordMgr`; refer to
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section :ref:`http-password-mgr` for information on the interface that must
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be supported. When both Digest Authentication Handler and Basic
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Authentication Handler are both added, Digest Authentication is always tried
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first. If the Digest Authentication returns a 40x response again, it is sent
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to Basic Authentication handler to Handle. This Handler method will raise a
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:exc:`ValueError` when presented with an authentication scheme other than
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Digest or Basic.
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.. versionchanged:: 3.3
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Raise :exc:`ValueError` on unsupported Authentication Scheme.
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.. class:: ProxyDigestAuthHandler(password_mgr=None)
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Handle authentication with the proxy. *password_mgr*, if given, should be
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something that is compatible with :class:`HTTPPasswordMgr`; refer to section
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:ref:`http-password-mgr` for information on the interface that must be
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supported.
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.. class:: HTTPHandler()
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A class to handle opening of HTTP URLs.
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.. class:: HTTPSHandler(debuglevel=0, context=None, check_hostname=None)
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A class to handle opening of HTTPS URLs. *context* and *check_hostname*
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have the same meaning as in :class:`http.client.HTTPSConnection`.
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.. versionchanged:: 3.2
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*context* and *check_hostname* were added.
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.. class:: FileHandler()
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Open local files.
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.. class:: DataHandler()
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Open data URLs.
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.. versionadded:: 3.4
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.. class:: FTPHandler()
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Open FTP URLs.
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.. class:: CacheFTPHandler()
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Open FTP URLs, keeping a cache of open FTP connections to minimize delays.
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.. class:: UnknownHandler()
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A catch-all class to handle unknown URLs.
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.. class:: HTTPErrorProcessor()
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Process HTTP error responses.
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.. _request-objects:
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Request Objects
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---------------
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The following methods describe :class:`Request`'s public interface,
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and so all may be overridden in subclasses. It also defines several
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public attributes that can be used by clients to inspect the parsed
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request.
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.. attribute:: Request.full_url
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The original URL passed to the constructor.
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.. versionchanged:: 3.4
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Request.full_url is a property with setter, getter and a deleter. Getting
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:attr:`~Request.full_url` returns the original request URL with the
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fragment, if it was present.
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.. attribute:: Request.type
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The URI scheme.
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.. attribute:: Request.host
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The URI authority, typically a host, but may also contain a port
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separated by a colon.
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.. attribute:: Request.origin_req_host
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The original host for the request, without port.
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.. attribute:: Request.selector
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|
|
The URI path. If the :class:`Request` uses a proxy, then selector
|
|
will be the full URL that is passed to the proxy.
|
|
|
|
.. attribute:: Request.data
|
|
|
|
The entity body for the request, or ``None`` if not specified.
|
|
|
|
.. versionchanged:: 3.4
|
|
Changing value of :attr:`Request.data` now deletes "Content-Length"
|
|
header if it was previously set or calculated.
|
|
|
|
.. attribute:: Request.unverifiable
|
|
|
|
boolean, indicates whether the request is unverifiable as defined
|
|
by :rfc:`2965`.
|
|
|
|
.. attribute:: Request.method
|
|
|
|
The HTTP request method to use. By default its value is :const:`None`,
|
|
which means that :meth:`~Request.get_method` will do its normal computation
|
|
of the method to be used. Its value can be set (thus overriding the default
|
|
computation in :meth:`~Request.get_method`) either by providing a default
|
|
value by setting it at the class level in a :class:`Request` subclass, or by
|
|
passing a value in to the :class:`Request` constructor via the *method*
|
|
argument.
|
|
|
|
.. versionadded:: 3.3
|
|
|
|
.. versionchanged:: 3.4
|
|
A default value can now be set in subclasses; previously it could only
|
|
be set via the constructor argument.
|
|
|
|
|
|
.. method:: Request.get_method()
|
|
|
|
Return a string indicating the HTTP request method. If
|
|
:attr:`Request.method` is not ``None``, return its value, otherwise return
|
|
``'GET'`` if :attr:`Request.data` is ``None``, or ``'POST'`` if it's not.
|
|
This is only meaningful for HTTP requests.
|
|
|
|
.. versionchanged:: 3.3
|
|
get_method now looks at the value of :attr:`Request.method`.
|
|
|
|
|
|
.. method:: Request.add_header(key, val)
|
|
|
|
Add another header to the request. Headers are currently ignored by all
|
|
handlers except HTTP handlers, where they are added to the list of headers sent
|
|
to the server. Note that there cannot be more than one header with the same
|
|
name, and later calls will overwrite previous calls in case the *key* collides.
|
|
Currently, this is no loss of HTTP functionality, since all headers which have
|
|
meaning when used more than once have a (header-specific) way of gaining the
|
|
same functionality using only one header. Note that headers added using
|
|
this method are also added to redirected requests.
|
|
|
|
|
|
.. method:: Request.add_unredirected_header(key, header)
|
|
|
|
Add a header that will not be added to a redirected request.
|
|
|
|
|
|
.. method:: Request.has_header(header)
|
|
|
|
Return whether the instance has the named header (checks both regular and
|
|
unredirected).
|
|
|
|
|
|
.. method:: Request.remove_header(header)
|
|
|
|
Remove named header from the request instance (both from regular and
|
|
unredirected headers).
|
|
|
|
.. versionadded:: 3.4
|
|
|
|
|
|
.. method:: Request.get_full_url()
|
|
|
|
Return the URL given in the constructor.
|
|
|
|
.. versionchanged:: 3.4
|
|
|
|
Returns :attr:`Request.full_url`
|
|
|
|
|
|
.. method:: Request.set_proxy(host, type)
|
|
|
|
Prepare the request by connecting to a proxy server. The *host* and *type* will
|
|
replace those of the instance, and the instance's selector will be the original
|
|
URL given in the constructor.
|
|
|
|
|
|
.. method:: Request.get_header(header_name, default=None)
|
|
|
|
Return the value of the given header. If the header is not present, return
|
|
the default value.
|
|
|
|
|
|
.. method:: Request.header_items()
|
|
|
|
Return a list of tuples (header_name, header_value) of the Request headers.
|
|
|
|
.. versionchanged:: 3.4
|
|
The request methods add_data, has_data, get_data, get_type, get_host,
|
|
get_selector, get_origin_req_host and is_unverifiable that were deprecated
|
|
since 3.3 have been removed.
|
|
|
|
|
|
.. _opener-director-objects:
|
|
|
|
OpenerDirector Objects
|
|
----------------------
|
|
|
|
:class:`OpenerDirector` instances have the following methods:
|
|
|
|
|
|
.. method:: OpenerDirector.add_handler(handler)
|
|
|
|
*handler* should be an instance of :class:`BaseHandler`. The following methods
|
|
are searched, and added to the possible chains (note that HTTP errors are a
|
|
special case). Note that, in the following, *protocol* should be replaced
|
|
with the actual protocol to handle, for example :meth:`http_response` would
|
|
be the HTTP protocol response handler. Also *type* should be replaced with
|
|
the actual HTTP code, for example :meth:`http_error_404` would handle HTTP
|
|
404 errors.
|
|
|
|
* :meth:`!<protocol>_open` --- signal that the handler knows how to open *protocol*
|
|
URLs.
|
|
|
|
See |protocol_open|_ for more information.
|
|
|
|
* :meth:`!http_error_\<type\>` --- signal that the handler knows how to handle HTTP
|
|
errors with HTTP error code *type*.
|
|
|
|
See |http_error_nnn|_ for more information.
|
|
|
|
* :meth:`!<protocol>_error` --- signal that the handler knows how to handle errors
|
|
from (non-\ ``http``) *protocol*.
|
|
|
|
* :meth:`!<protocol>_request` --- signal that the handler knows how to pre-process
|
|
*protocol* requests.
|
|
|
|
See |protocol_request|_ for more information.
|
|
|
|
* :meth:`!<protocol>_response` --- signal that the handler knows how to
|
|
post-process *protocol* responses.
|
|
|
|
See |protocol_response|_ for more information.
|
|
|
|
.. |protocol_open| replace:: :meth:`BaseHandler.<protocol>_open`
|
|
.. |http_error_nnn| replace:: :meth:`BaseHandler.http_error_\<nnn\>`
|
|
.. |protocol_request| replace:: :meth:`BaseHandler.<protocol>_request`
|
|
.. |protocol_response| replace:: :meth:`BaseHandler.<protocol>_response`
|
|
|
|
.. method:: OpenerDirector.open(url, data=None[, timeout])
|
|
|
|
Open the given *url* (which can be a request object or a string), optionally
|
|
passing the given *data*. Arguments, return values and exceptions raised are
|
|
the same as those of :func:`urlopen` (which simply calls the :meth:`open`
|
|
method on the currently installed global :class:`OpenerDirector`). The
|
|
optional *timeout* parameter specifies a timeout in seconds for blocking
|
|
operations like the connection attempt (if not specified, the global default
|
|
timeout setting will be used). The timeout feature actually works only for
|
|
HTTP, HTTPS and FTP connections.
|
|
|
|
|
|
.. method:: OpenerDirector.error(proto, *args)
|
|
|
|
Handle an error of the given protocol. This will call the registered error
|
|
handlers for the given protocol with the given arguments (which are protocol
|
|
specific). The HTTP protocol is a special case which uses the HTTP response
|
|
code to determine the specific error handler; refer to the :meth:`!http_error_\<type\>`
|
|
methods of the handler classes.
|
|
|
|
Return values and exceptions raised are the same as those of :func:`urlopen`.
|
|
|
|
OpenerDirector objects open URLs in three stages:
|
|
|
|
The order in which these methods are called within each stage is determined by
|
|
sorting the handler instances.
|
|
|
|
#. Every handler with a method named like :meth:`!<protocol>_request` has that
|
|
method called to pre-process the request.
|
|
|
|
#. Handlers with a method named like :meth:`!<protocol>_open` are called to handle
|
|
the request. This stage ends when a handler either returns a non-\ :const:`None`
|
|
value (ie. a response), or raises an exception (usually
|
|
:exc:`~urllib.error.URLError`). Exceptions are allowed to propagate.
|
|
|
|
In fact, the above algorithm is first tried for methods named
|
|
:meth:`~BaseHandler.default_open`. If all such methods return :const:`None`, the algorithm
|
|
is repeated for methods named like :meth:`!<protocol>_open`. If all such methods
|
|
return :const:`None`, the algorithm is repeated for methods named
|
|
:meth:`~BaseHandler.unknown_open`.
|
|
|
|
Note that the implementation of these methods may involve calls of the parent
|
|
:class:`OpenerDirector` instance's :meth:`~OpenerDirector.open` and
|
|
:meth:`~OpenerDirector.error` methods.
|
|
|
|
#. Every handler with a method named like :meth:`!<protocol>_response` has that
|
|
method called to post-process the response.
|
|
|
|
|
|
.. _base-handler-objects:
|
|
|
|
BaseHandler Objects
|
|
-------------------
|
|
|
|
:class:`BaseHandler` objects provide a couple of methods that are directly
|
|
useful, and others that are meant to be used by derived classes. These are
|
|
intended for direct use:
|
|
|
|
|
|
.. method:: BaseHandler.add_parent(director)
|
|
|
|
Add a director as parent.
|
|
|
|
|
|
.. method:: BaseHandler.close()
|
|
|
|
Remove any parents.
|
|
|
|
The following attribute and methods should only be used by classes derived from
|
|
:class:`BaseHandler`.
|
|
|
|
.. note::
|
|
|
|
The convention has been adopted that subclasses defining
|
|
:meth:`!<protocol>_request` or :meth:`!<protocol>_response` methods are named
|
|
:class:`!\*Processor`; all others are named :class:`!\*Handler`.
|
|
|
|
|
|
.. attribute:: BaseHandler.parent
|
|
|
|
A valid :class:`OpenerDirector`, which can be used to open using a different
|
|
protocol, or handle errors.
|
|
|
|
|
|
.. method:: BaseHandler.default_open(req)
|
|
|
|
This method is *not* defined in :class:`BaseHandler`, but subclasses should
|
|
define it if they want to catch all URLs.
|
|
|
|
This method, if implemented, will be called by the parent
|
|
:class:`OpenerDirector`. It should return a file-like object as described in
|
|
the return value of the :meth:`~OpenerDirector.open` method of :class:`OpenerDirector`, or ``None``.
|
|
It should raise :exc:`~urllib.error.URLError`, unless a truly exceptional
|
|
thing happens (for example, :exc:`MemoryError` should not be mapped to
|
|
:exc:`~urllib.error.URLError`).
|
|
|
|
This method will be called before any protocol-specific open method.
|
|
|
|
|
|
.. _protocol_open:
|
|
.. method:: BaseHandler.<protocol>_open(req)
|
|
:noindex:
|
|
|
|
This method is *not* defined in :class:`BaseHandler`, but subclasses should
|
|
define it if they want to handle URLs with the given protocol.
|
|
|
|
This method, if defined, will be called by the parent :class:`OpenerDirector`.
|
|
Return values should be the same as for :meth:`~BaseHandler.default_open`.
|
|
|
|
|
|
.. method:: BaseHandler.unknown_open(req)
|
|
|
|
This method is *not* defined in :class:`BaseHandler`, but subclasses should
|
|
define it if they want to catch all URLs with no specific registered handler to
|
|
open it.
|
|
|
|
This method, if implemented, will be called by the :attr:`parent`
|
|
:class:`OpenerDirector`. Return values should be the same as for
|
|
:meth:`default_open`.
|
|
|
|
|
|
.. method:: BaseHandler.http_error_default(req, fp, code, msg, hdrs)
|
|
|
|
This method is *not* defined in :class:`BaseHandler`, but subclasses should
|
|
override it if they intend to provide a catch-all for otherwise unhandled HTTP
|
|
errors. It will be called automatically by the :class:`OpenerDirector` getting
|
|
the error, and should not normally be called in other circumstances.
|
|
|
|
*req* will be a :class:`Request` object, *fp* will be a file-like object with
|
|
the HTTP error body, *code* will be the three-digit code of the error, *msg*
|
|
will be the user-visible explanation of the code and *hdrs* will be a mapping
|
|
object with the headers of the error.
|
|
|
|
Return values and exceptions raised should be the same as those of
|
|
:func:`urlopen`.
|
|
|
|
|
|
.. _http_error_nnn:
|
|
.. method:: BaseHandler.http_error_<nnn>(req, fp, code, msg, hdrs)
|
|
|
|
*nnn* should be a three-digit HTTP error code. This method is also not defined
|
|
in :class:`BaseHandler`, but will be called, if it exists, on an instance of a
|
|
subclass, when an HTTP error with code *nnn* occurs.
|
|
|
|
Subclasses should override this method to handle specific HTTP errors.
|
|
|
|
Arguments, return values and exceptions raised should be the same as for
|
|
:meth:`~BaseHandler.http_error_default`.
|
|
|
|
|
|
.. _protocol_request:
|
|
.. method:: BaseHandler.<protocol>_request(req)
|
|
:noindex:
|
|
|
|
This method is *not* defined in :class:`BaseHandler`, but subclasses should
|
|
define it if they want to pre-process requests of the given protocol.
|
|
|
|
This method, if defined, will be called by the parent :class:`OpenerDirector`.
|
|
*req* will be a :class:`Request` object. The return value should be a
|
|
:class:`Request` object.
|
|
|
|
|
|
.. _protocol_response:
|
|
.. method:: BaseHandler.<protocol>_response(req, response)
|
|
:noindex:
|
|
|
|
This method is *not* defined in :class:`BaseHandler`, but subclasses should
|
|
define it if they want to post-process responses of the given protocol.
|
|
|
|
This method, if defined, will be called by the parent :class:`OpenerDirector`.
|
|
*req* will be a :class:`Request` object. *response* will be an object
|
|
implementing the same interface as the return value of :func:`urlopen`. The
|
|
return value should implement the same interface as the return value of
|
|
:func:`urlopen`.
|
|
|
|
|
|
.. _http-redirect-handler:
|
|
|
|
HTTPRedirectHandler Objects
|
|
---------------------------
|
|
|
|
.. note::
|
|
|
|
Some HTTP redirections require action from this module's client code. If this
|
|
is the case, :exc:`~urllib.error.HTTPError` is raised. See :rfc:`2616` for
|
|
details of the precise meanings of the various redirection codes.
|
|
|
|
An :exc:`~urllib.error.HTTPError` exception raised as a security consideration if the
|
|
HTTPRedirectHandler is presented with a redirected URL which is not an HTTP,
|
|
HTTPS or FTP URL.
|
|
|
|
|
|
.. method:: HTTPRedirectHandler.redirect_request(req, fp, code, msg, hdrs, newurl)
|
|
|
|
Return a :class:`Request` or ``None`` in response to a redirect. This is called
|
|
by the default implementations of the :meth:`!http_error_30\*` methods when a
|
|
redirection is received from the server. If a redirection should take place,
|
|
return a new :class:`Request` to allow :meth:`!http_error_30\*` to perform the
|
|
redirect to *newurl*. Otherwise, raise :exc:`~urllib.error.HTTPError` if
|
|
no other handler should try to handle this URL, or return ``None`` if you
|
|
can't but another handler might.
|
|
|
|
.. note::
|
|
|
|
The default implementation of this method does not strictly follow :rfc:`2616`,
|
|
which says that 301 and 302 responses to ``POST`` requests must not be
|
|
automatically redirected without confirmation by the user. In reality, browsers
|
|
do allow automatic redirection of these responses, changing the POST to a
|
|
``GET``, and the default implementation reproduces this behavior.
|
|
|
|
|
|
.. method:: HTTPRedirectHandler.http_error_301(req, fp, code, msg, hdrs)
|
|
|
|
Redirect to the ``Location:`` or ``URI:`` URL. This method is called by the
|
|
parent :class:`OpenerDirector` when getting an HTTP 'moved permanently' response.
|
|
|
|
|
|
.. method:: HTTPRedirectHandler.http_error_302(req, fp, code, msg, hdrs)
|
|
|
|
The same as :meth:`http_error_301`, but called for the 'found' response.
|
|
|
|
|
|
.. method:: HTTPRedirectHandler.http_error_303(req, fp, code, msg, hdrs)
|
|
|
|
The same as :meth:`http_error_301`, but called for the 'see other' response.
|
|
|
|
|
|
.. method:: HTTPRedirectHandler.http_error_307(req, fp, code, msg, hdrs)
|
|
|
|
The same as :meth:`http_error_301`, but called for the 'temporary redirect'
|
|
response. It does not allow changing the request method from ``POST``
|
|
to ``GET``.
|
|
|
|
|
|
.. method:: HTTPRedirectHandler.http_error_308(req, fp, code, msg, hdrs)
|
|
|
|
The same as :meth:`http_error_301`, but called for the 'permanent redirect'
|
|
response. It does not allow changing the request method from ``POST``
|
|
to ``GET``.
|
|
|
|
.. versionadded:: 3.11
|
|
|
|
|
|
.. _http-cookie-processor:
|
|
|
|
HTTPCookieProcessor Objects
|
|
---------------------------
|
|
|
|
:class:`HTTPCookieProcessor` instances have one attribute:
|
|
|
|
.. attribute:: HTTPCookieProcessor.cookiejar
|
|
|
|
The :class:`http.cookiejar.CookieJar` in which cookies are stored.
|
|
|
|
|
|
.. _proxy-handler:
|
|
|
|
ProxyHandler Objects
|
|
--------------------
|
|
|
|
|
|
.. method:: ProxyHandler.<protocol>_open(request)
|
|
:noindex:
|
|
|
|
The :class:`ProxyHandler` will have a method :meth:`!<protocol>_open` for every
|
|
*protocol* which has a proxy in the *proxies* dictionary given in the
|
|
constructor. The method will modify requests to go through the proxy, by
|
|
calling ``request.set_proxy()``, and call the next handler in the chain to
|
|
actually execute the protocol.
|
|
|
|
|
|
.. _http-password-mgr:
|
|
|
|
HTTPPasswordMgr Objects
|
|
-----------------------
|
|
|
|
These methods are available on :class:`HTTPPasswordMgr` and
|
|
:class:`HTTPPasswordMgrWithDefaultRealm` objects.
|
|
|
|
|
|
.. method:: HTTPPasswordMgr.add_password(realm, uri, user, passwd)
|
|
|
|
*uri* can be either a single URI, or a sequence of URIs. *realm*, *user* and
|
|
*passwd* must be strings. This causes ``(user, passwd)`` to be used as
|
|
authentication tokens when authentication for *realm* and a super-URI of any of
|
|
the given URIs is given.
|
|
|
|
|
|
.. method:: HTTPPasswordMgr.find_user_password(realm, authuri)
|
|
|
|
Get user/password for given realm and URI, if any. This method will return
|
|
``(None, None)`` if there is no matching user/password.
|
|
|
|
For :class:`HTTPPasswordMgrWithDefaultRealm` objects, the realm ``None`` will be
|
|
searched if the given *realm* has no matching user/password.
|
|
|
|
|
|
.. _http-password-mgr-with-prior-auth:
|
|
|
|
HTTPPasswordMgrWithPriorAuth Objects
|
|
------------------------------------
|
|
|
|
This password manager extends :class:`HTTPPasswordMgrWithDefaultRealm` to support
|
|
tracking URIs for which authentication credentials should always be sent.
|
|
|
|
|
|
.. method:: HTTPPasswordMgrWithPriorAuth.add_password(realm, uri, user, \
|
|
passwd, is_authenticated=False)
|
|
|
|
*realm*, *uri*, *user*, *passwd* are as for
|
|
:meth:`HTTPPasswordMgr.add_password`. *is_authenticated* sets the initial
|
|
value of the ``is_authenticated`` flag for the given URI or list of URIs.
|
|
If *is_authenticated* is specified as ``True``, *realm* is ignored.
|
|
|
|
|
|
.. method:: HTTPPasswordMgrWithPriorAuth.find_user_password(realm, authuri)
|
|
|
|
Same as for :class:`HTTPPasswordMgrWithDefaultRealm` objects
|
|
|
|
|
|
.. method:: HTTPPasswordMgrWithPriorAuth.update_authenticated(self, uri, \
|
|
is_authenticated=False)
|
|
|
|
Update the ``is_authenticated`` flag for the given *uri* or list
|
|
of URIs.
|
|
|
|
|
|
.. method:: HTTPPasswordMgrWithPriorAuth.is_authenticated(self, authuri)
|
|
|
|
Returns the current state of the ``is_authenticated`` flag for
|
|
the given URI.
|
|
|
|
|
|
.. _abstract-basic-auth-handler:
|
|
|
|
AbstractBasicAuthHandler Objects
|
|
--------------------------------
|
|
|
|
|
|
.. method:: AbstractBasicAuthHandler.http_error_auth_reqed(authreq, host, req, headers)
|
|
|
|
Handle an authentication request by getting a user/password pair, and re-trying
|
|
the request. *authreq* should be the name of the header where the information
|
|
about the realm is included in the request, *host* specifies the URL and path to
|
|
authenticate for, *req* should be the (failed) :class:`Request` object, and
|
|
*headers* should be the error headers.
|
|
|
|
*host* is either an authority (e.g. ``"python.org"``) or a URL containing an
|
|
authority component (e.g. ``"http://python.org/"``). In either case, the
|
|
authority must not contain a userinfo component (so, ``"python.org"`` and
|
|
``"python.org:80"`` are fine, ``"joe:password@python.org"`` is not).
|
|
|
|
|
|
.. _http-basic-auth-handler:
|
|
|
|
HTTPBasicAuthHandler Objects
|
|
----------------------------
|
|
|
|
|
|
.. method:: HTTPBasicAuthHandler.http_error_401(req, fp, code, msg, hdrs)
|
|
|
|
Retry the request with authentication information, if available.
|
|
|
|
|
|
.. _proxy-basic-auth-handler:
|
|
|
|
ProxyBasicAuthHandler Objects
|
|
-----------------------------
|
|
|
|
|
|
.. method:: ProxyBasicAuthHandler.http_error_407(req, fp, code, msg, hdrs)
|
|
|
|
Retry the request with authentication information, if available.
|
|
|
|
|
|
.. _abstract-digest-auth-handler:
|
|
|
|
AbstractDigestAuthHandler Objects
|
|
---------------------------------
|
|
|
|
|
|
.. method:: AbstractDigestAuthHandler.http_error_auth_reqed(authreq, host, req, headers)
|
|
|
|
*authreq* should be the name of the header where the information about the realm
|
|
is included in the request, *host* should be the host to authenticate to, *req*
|
|
should be the (failed) :class:`Request` object, and *headers* should be the
|
|
error headers.
|
|
|
|
|
|
.. _http-digest-auth-handler:
|
|
|
|
HTTPDigestAuthHandler Objects
|
|
-----------------------------
|
|
|
|
|
|
.. method:: HTTPDigestAuthHandler.http_error_401(req, fp, code, msg, hdrs)
|
|
|
|
Retry the request with authentication information, if available.
|
|
|
|
|
|
.. _proxy-digest-auth-handler:
|
|
|
|
ProxyDigestAuthHandler Objects
|
|
------------------------------
|
|
|
|
|
|
.. method:: ProxyDigestAuthHandler.http_error_407(req, fp, code, msg, hdrs)
|
|
|
|
Retry the request with authentication information, if available.
|
|
|
|
|
|
.. _http-handler-objects:
|
|
|
|
HTTPHandler Objects
|
|
-------------------
|
|
|
|
|
|
.. method:: HTTPHandler.http_open(req)
|
|
|
|
Send an HTTP request, which can be either GET or POST, depending on
|
|
``req.has_data()``.
|
|
|
|
|
|
.. _https-handler-objects:
|
|
|
|
HTTPSHandler Objects
|
|
--------------------
|
|
|
|
|
|
.. method:: HTTPSHandler.https_open(req)
|
|
|
|
Send an HTTPS request, which can be either GET or POST, depending on
|
|
``req.has_data()``.
|
|
|
|
|
|
.. _file-handler-objects:
|
|
|
|
FileHandler Objects
|
|
-------------------
|
|
|
|
|
|
.. method:: FileHandler.file_open(req)
|
|
|
|
Open the file locally, if there is no host name, or the host name is
|
|
``'localhost'``.
|
|
|
|
.. versionchanged:: 3.2
|
|
This method is applicable only for local hostnames. When a remote
|
|
hostname is given, a :exc:`~urllib.error.URLError` is raised.
|
|
|
|
|
|
.. _data-handler-objects:
|
|
|
|
DataHandler Objects
|
|
-------------------
|
|
|
|
.. method:: DataHandler.data_open(req)
|
|
|
|
Read a data URL. This kind of URL contains the content encoded in the URL
|
|
itself. The data URL syntax is specified in :rfc:`2397`. This implementation
|
|
ignores white spaces in base64 encoded data URLs so the URL may be wrapped
|
|
in whatever source file it comes from. But even though some browsers don't
|
|
mind about a missing padding at the end of a base64 encoded data URL, this
|
|
implementation will raise a :exc:`ValueError` in that case.
|
|
|
|
|
|
.. _ftp-handler-objects:
|
|
|
|
FTPHandler Objects
|
|
------------------
|
|
|
|
|
|
.. method:: FTPHandler.ftp_open(req)
|
|
|
|
Open the FTP file indicated by *req*. The login is always done with empty
|
|
username and password.
|
|
|
|
|
|
.. _cacheftp-handler-objects:
|
|
|
|
CacheFTPHandler Objects
|
|
-----------------------
|
|
|
|
:class:`CacheFTPHandler` objects are :class:`FTPHandler` objects with the
|
|
following additional methods:
|
|
|
|
|
|
.. method:: CacheFTPHandler.setTimeout(t)
|
|
|
|
Set timeout of connections to *t* seconds.
|
|
|
|
|
|
.. method:: CacheFTPHandler.setMaxConns(m)
|
|
|
|
Set maximum number of cached connections to *m*.
|
|
|
|
|
|
.. _unknown-handler-objects:
|
|
|
|
UnknownHandler Objects
|
|
----------------------
|
|
|
|
|
|
.. method:: UnknownHandler.unknown_open()
|
|
|
|
Raise a :exc:`~urllib.error.URLError` exception.
|
|
|
|
|
|
.. _http-error-processor-objects:
|
|
|
|
HTTPErrorProcessor Objects
|
|
--------------------------
|
|
|
|
.. method:: HTTPErrorProcessor.http_response(request, response)
|
|
|
|
Process HTTP error responses.
|
|
|
|
For 200 error codes, the response object is returned immediately.
|
|
|
|
For non-200 error codes, this simply passes the job on to the
|
|
:meth:`!http_error_\<type\>` handler methods, via :meth:`OpenerDirector.error`.
|
|
Eventually, :class:`HTTPDefaultErrorHandler` will raise an
|
|
:exc:`~urllib.error.HTTPError` if no other handler handles the error.
|
|
|
|
|
|
.. method:: HTTPErrorProcessor.https_response(request, response)
|
|
|
|
Process HTTPS error responses.
|
|
|
|
The behavior is same as :meth:`http_response`.
|
|
|
|
|
|
.. _urllib-request-examples:
|
|
|
|
Examples
|
|
--------
|
|
|
|
In addition to the examples below, more examples are given in
|
|
:ref:`urllib-howto`.
|
|
|
|
This example gets the python.org main page and displays the first 300 bytes of
|
|
it. ::
|
|
|
|
>>> import urllib.request
|
|
>>> with urllib.request.urlopen('http://www.python.org/') as f:
|
|
... print(f.read(300))
|
|
...
|
|
b'<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
|
|
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">\n\n\n<html
|
|
xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">\n\n<head>\n
|
|
<meta http-equiv="content-type" content="text/html; charset=utf-8" />\n
|
|
<title>Python Programming '
|
|
|
|
Note that urlopen returns a bytes object. This is because there is no way
|
|
for urlopen to automatically determine the encoding of the byte stream
|
|
it receives from the HTTP server. In general, a program will decode
|
|
the returned bytes object to string once it determines or guesses
|
|
the appropriate encoding.
|
|
|
|
The following W3C document, https://www.w3.org/International/O-charset\ , lists
|
|
the various ways in which an (X)HTML or an XML document could have specified its
|
|
encoding information.
|
|
|
|
As the python.org website uses *utf-8* encoding as specified in its meta tag, we
|
|
will use the same for decoding the bytes object. ::
|
|
|
|
>>> with urllib.request.urlopen('http://www.python.org/') as f:
|
|
... print(f.read(100).decode('utf-8'))
|
|
...
|
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
|
|
"http://www.w3.org/TR/xhtml1/DTD/xhtm
|
|
|
|
It is also possible to achieve the same result without using the
|
|
:term:`context manager` approach. ::
|
|
|
|
>>> import urllib.request
|
|
>>> f = urllib.request.urlopen('http://www.python.org/')
|
|
>>> print(f.read(100).decode('utf-8'))
|
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
|
|
"http://www.w3.org/TR/xhtml1/DTD/xhtm
|
|
|
|
In the following example, we are sending a data-stream to the stdin of a CGI
|
|
and reading the data it returns to us. Note that this example will only work
|
|
when the Python installation supports SSL. ::
|
|
|
|
>>> import urllib.request
|
|
>>> req = urllib.request.Request(url='https://localhost/cgi-bin/test.cgi',
|
|
... data=b'This data is passed to stdin of the CGI')
|
|
>>> with urllib.request.urlopen(req) as f:
|
|
... print(f.read().decode('utf-8'))
|
|
...
|
|
Got Data: "This data is passed to stdin of the CGI"
|
|
|
|
The code for the sample CGI used in the above example is::
|
|
|
|
#!/usr/bin/env python
|
|
import sys
|
|
data = sys.stdin.read()
|
|
print('Content-type: text/plain\n\nGot Data: "%s"' % data)
|
|
|
|
Here is an example of doing a ``PUT`` request using :class:`Request`::
|
|
|
|
import urllib.request
|
|
DATA = b'some data'
|
|
req = urllib.request.Request(url='http://localhost:8080', data=DATA, method='PUT')
|
|
with urllib.request.urlopen(req) as f:
|
|
pass
|
|
print(f.status)
|
|
print(f.reason)
|
|
|
|
Use of Basic HTTP Authentication::
|
|
|
|
import urllib.request
|
|
# Create an OpenerDirector with support for Basic HTTP Authentication...
|
|
auth_handler = urllib.request.HTTPBasicAuthHandler()
|
|
auth_handler.add_password(realm='PDQ Application',
|
|
uri='https://mahler:8092/site-updates.py',
|
|
user='klem',
|
|
passwd='kadidd!ehopper')
|
|
opener = urllib.request.build_opener(auth_handler)
|
|
# ...and install it globally so it can be used with urlopen.
|
|
urllib.request.install_opener(opener)
|
|
urllib.request.urlopen('http://www.example.com/login.html')
|
|
|
|
:func:`build_opener` provides many handlers by default, including a
|
|
:class:`ProxyHandler`. By default, :class:`ProxyHandler` uses the environment
|
|
variables named ``<scheme>_proxy``, where ``<scheme>`` is the URL scheme
|
|
involved. For example, the :envvar:`!http_proxy` environment variable is read to
|
|
obtain the HTTP proxy's URL.
|
|
|
|
This example replaces the default :class:`ProxyHandler` with one that uses
|
|
programmatically supplied proxy URLs, and adds proxy authorization support with
|
|
:class:`ProxyBasicAuthHandler`. ::
|
|
|
|
proxy_handler = urllib.request.ProxyHandler({'http': 'http://www.example.com:3128/'})
|
|
proxy_auth_handler = urllib.request.ProxyBasicAuthHandler()
|
|
proxy_auth_handler.add_password('realm', 'host', 'username', 'password')
|
|
|
|
opener = urllib.request.build_opener(proxy_handler, proxy_auth_handler)
|
|
# This time, rather than install the OpenerDirector, we use it directly:
|
|
opener.open('http://www.example.com/login.html')
|
|
|
|
Adding HTTP headers:
|
|
|
|
Use the *headers* argument to the :class:`Request` constructor, or::
|
|
|
|
import urllib.request
|
|
req = urllib.request.Request('http://www.example.com/')
|
|
req.add_header('Referer', 'http://www.python.org/')
|
|
# Customize the default User-Agent header value:
|
|
req.add_header('User-Agent', 'urllib-example/0.1 (Contact: . . .)')
|
|
r = urllib.request.urlopen(req)
|
|
|
|
:class:`OpenerDirector` automatically adds a :mailheader:`User-Agent` header to
|
|
every :class:`Request`. To change this::
|
|
|
|
import urllib.request
|
|
opener = urllib.request.build_opener()
|
|
opener.addheaders = [('User-agent', 'Mozilla/5.0')]
|
|
opener.open('http://www.example.com/')
|
|
|
|
Also, remember that a few standard headers (:mailheader:`Content-Length`,
|
|
:mailheader:`Content-Type` and :mailheader:`Host`)
|
|
are added when the :class:`Request` is passed to :func:`urlopen` (or
|
|
:meth:`OpenerDirector.open`).
|
|
|
|
.. _urllib-examples:
|
|
|
|
Here is an example session that uses the ``GET`` method to retrieve a URL
|
|
containing parameters::
|
|
|
|
>>> import urllib.request
|
|
>>> import urllib.parse
|
|
>>> params = urllib.parse.urlencode({'spam': 1, 'eggs': 2, 'bacon': 0})
|
|
>>> url = "http://www.musi-cal.com/cgi-bin/query?%s" % params
|
|
>>> with urllib.request.urlopen(url) as f:
|
|
... print(f.read().decode('utf-8'))
|
|
...
|
|
|
|
The following example uses the ``POST`` method instead. Note that params output
|
|
from urlencode is encoded to bytes before it is sent to urlopen as data::
|
|
|
|
>>> import urllib.request
|
|
>>> import urllib.parse
|
|
>>> data = urllib.parse.urlencode({'spam': 1, 'eggs': 2, 'bacon': 0})
|
|
>>> data = data.encode('ascii')
|
|
>>> with urllib.request.urlopen("http://requestb.in/xrbl82xr", data) as f:
|
|
... print(f.read().decode('utf-8'))
|
|
...
|
|
|
|
The following example uses an explicitly specified HTTP proxy, overriding
|
|
environment settings::
|
|
|
|
>>> import urllib.request
|
|
>>> proxies = {'http': 'http://proxy.example.com:8080/'}
|
|
>>> opener = urllib.request.build_opener(urllib.request.ProxyHandler(proxies))
|
|
>>> with opener.open("http://www.python.org") as f:
|
|
... f.read().decode('utf-8')
|
|
...
|
|
|
|
The following example uses no proxies at all, overriding environment settings::
|
|
|
|
>>> import urllib.request
|
|
>>> opener = urllib.request.build_opener(urllib.request.ProxyHandler({}}))
|
|
>>> with opener.open("http://www.python.org/") as f:
|
|
... f.read().decode('utf-8')
|
|
...
|
|
|
|
|
|
Legacy interface
|
|
----------------
|
|
|
|
The following functions and classes are ported from the Python 2 module
|
|
``urllib`` (as opposed to ``urllib2``). They might become deprecated at
|
|
some point in the future.
|
|
|
|
.. function:: urlretrieve(url, filename=None, reporthook=None, data=None)
|
|
|
|
Copy a network object denoted by a URL to a local file. If the URL
|
|
points to a local file, the object will not be copied unless filename is supplied.
|
|
Return a tuple ``(filename, headers)`` where *filename* is the
|
|
local file name under which the object can be found, and *headers* is whatever
|
|
the :meth:`!info` method of the object returned by :func:`urlopen` returned (for
|
|
a remote object). Exceptions are the same as for :func:`urlopen`.
|
|
|
|
The second argument, if present, specifies the file location to copy to (if
|
|
absent, the location will be a tempfile with a generated name). The third
|
|
argument, if present, is a callable that will be called once on
|
|
establishment of the network connection and once after each block read
|
|
thereafter. The callable will be passed three arguments; a count of blocks
|
|
transferred so far, a block size in bytes, and the total size of the file. The
|
|
third argument may be ``-1`` on older FTP servers which do not return a file
|
|
size in response to a retrieval request.
|
|
|
|
The following example illustrates the most common usage scenario::
|
|
|
|
>>> import urllib.request
|
|
>>> local_filename, headers = urllib.request.urlretrieve('http://python.org/')
|
|
>>> html = open(local_filename)
|
|
>>> html.close()
|
|
|
|
If the *url* uses the :file:`http:` scheme identifier, the optional *data*
|
|
argument may be given to specify a ``POST`` request (normally the request
|
|
type is ``GET``). The *data* argument must be a bytes object in standard
|
|
:mimetype:`application/x-www-form-urlencoded` format; see the
|
|
:func:`urllib.parse.urlencode` function.
|
|
|
|
:func:`urlretrieve` will raise :exc:`~urllib.error.ContentTooShortError` when it detects that
|
|
the amount of data available was less than the expected amount (which is the
|
|
size reported by a *Content-Length* header). This can occur, for example, when
|
|
the download is interrupted.
|
|
|
|
The *Content-Length* is treated as a lower bound: if there's more data to read,
|
|
urlretrieve reads more data, but if less data is available, it raises the
|
|
exception.
|
|
|
|
You can still retrieve the downloaded data in this case, it is stored in the
|
|
:attr:`!content` attribute of the exception instance.
|
|
|
|
If no *Content-Length* header was supplied, urlretrieve can not check the size
|
|
of the data it has downloaded, and just returns it. In this case you just have
|
|
to assume that the download was successful.
|
|
|
|
.. function:: urlcleanup()
|
|
|
|
Cleans up temporary files that may have been left behind by previous
|
|
calls to :func:`urlretrieve`.
|
|
|
|
|
|
:mod:`urllib.request` Restrictions
|
|
----------------------------------
|
|
|
|
.. index::
|
|
pair: HTTP; protocol
|
|
pair: FTP; protocol
|
|
|
|
* Currently, only the following protocols are supported: HTTP (versions 0.9 and
|
|
1.0), FTP, local files, and data URLs.
|
|
|
|
.. versionchanged:: 3.4 Added support for data URLs.
|
|
|
|
* The caching feature of :func:`urlretrieve` has been disabled until someone
|
|
finds the time to hack proper processing of Expiration time headers.
|
|
|
|
* There should be a function to query whether a particular URL is in the cache.
|
|
|
|
* For backward compatibility, if a URL appears to point to a local file but the
|
|
file can't be opened, the URL is re-interpreted using the FTP protocol. This
|
|
can sometimes cause confusing error messages.
|
|
|
|
* The :func:`urlopen` and :func:`urlretrieve` functions can cause arbitrarily
|
|
long delays while waiting for a network connection to be set up. This means
|
|
that it is difficult to build an interactive web client using these functions
|
|
without using threads.
|
|
|
|
.. index::
|
|
single: HTML
|
|
pair: HTTP; protocol
|
|
|
|
* The data returned by :func:`urlopen` or :func:`urlretrieve` is the raw data
|
|
returned by the server. This may be binary data (such as an image), plain text
|
|
or (for example) HTML. The HTTP protocol provides type information in the reply
|
|
header, which can be inspected by looking at the :mailheader:`Content-Type`
|
|
header. If the returned data is HTML, you can use the module
|
|
:mod:`html.parser` to parse it.
|
|
|
|
.. index:: single: FTP
|
|
|
|
* The code handling the FTP protocol cannot differentiate between a file and a
|
|
directory. This can lead to unexpected behavior when attempting to read a URL
|
|
that points to a file that is not accessible. If the URL ends in a ``/``, it is
|
|
assumed to refer to a directory and will be handled accordingly. But if an
|
|
attempt to read a file leads to a 550 error (meaning the URL cannot be found or
|
|
is not accessible, often for permission reasons), then the path is treated as a
|
|
directory in order to handle the case when a directory is specified by a URL but
|
|
the trailing ``/`` has been left off. This can cause misleading results when
|
|
you try to fetch a file whose read permissions make it inaccessible; the FTP
|
|
code will try to read it, fail with a 550 error, and then perform a directory
|
|
listing for the unreadable file. If fine-grained control is needed, consider
|
|
using the :mod:`ftplib` module.
|
|
|
|
|
|
|
|
:mod:`urllib.response` --- Response classes used by urllib
|
|
==========================================================
|
|
|
|
.. module:: urllib.response
|
|
:synopsis: Response classes used by urllib.
|
|
|
|
The :mod:`urllib.response` module defines functions and classes which define a
|
|
minimal file-like interface, including ``read()`` and ``readline()``.
|
|
Functions defined by this module are used internally by the :mod:`urllib.request` module.
|
|
The typical response object is a :class:`urllib.response.addinfourl` instance:
|
|
|
|
.. class:: addinfourl
|
|
|
|
.. attribute:: url
|
|
|
|
URL of the resource retrieved, commonly used to determine if a redirect was followed.
|
|
|
|
.. attribute:: headers
|
|
|
|
Returns the headers of the response in the form of an :class:`~email.message.EmailMessage` instance.
|
|
|
|
.. attribute:: status
|
|
|
|
.. versionadded:: 3.9
|
|
|
|
Status code returned by server.
|
|
|
|
.. method:: geturl()
|
|
|
|
.. deprecated:: 3.9
|
|
Deprecated in favor of :attr:`~addinfourl.url`.
|
|
|
|
.. method:: info()
|
|
|
|
.. deprecated:: 3.9
|
|
Deprecated in favor of :attr:`~addinfourl.headers`.
|
|
|
|
.. attribute:: code
|
|
|
|
.. deprecated:: 3.9
|
|
Deprecated in favor of :attr:`~addinfourl.status`.
|
|
|
|
.. method:: getcode()
|
|
|
|
.. deprecated:: 3.9
|
|
Deprecated in favor of :attr:`~addinfourl.status`.
|