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52dbbb9068
Code contributed by Matt Giuca. quote() now encodes the input before quoting, unquote() decodes after unquoting. There are new arguments to change the encoding and errors settings. There are also new APIs to skip the encode/decode steps. [un]quote_plus() are also affected.
348 lines
16 KiB
ReStructuredText
348 lines
16 KiB
ReStructuredText
:mod:`urllib.parse` --- Parse URLs into components
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==================================================
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.. module:: urllib.parse
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:synopsis: Parse URLs into or assemble them from components.
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.. index::
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single: WWW
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single: World Wide Web
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single: URL
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pair: URL; parsing
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pair: relative; URL
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This module defines a standard interface to break Uniform Resource Locator (URL)
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strings up in components (addressing scheme, network location, path etc.), to
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combine the components back into a URL string, and to convert a "relative URL"
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to an absolute URL given a "base URL."
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The module has been designed to match the Internet RFC on Relative Uniform
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Resource Locators (and discovered a bug in an earlier draft!). It supports the
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following URL schemes: ``file``, ``ftp``, ``gopher``, ``hdl``, ``http``,
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``https``, ``imap``, ``mailto``, ``mms``, ``news``, ``nntp``, ``prospero``,
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``rsync``, ``rtsp``, ``rtspu``, ``sftp``, ``shttp``, ``sip``, ``sips``,
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``snews``, ``svn``, ``svn+ssh``, ``telnet``, ``wais``.
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The :mod:`urllib.parse` module defines the following functions:
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.. function:: urlparse(urlstring[, default_scheme[, allow_fragments]])
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Parse a URL into six components, returning a 6-tuple. This corresponds to the
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general structure of a URL: ``scheme://netloc/path;parameters?query#fragment``.
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Each tuple item is a string, possibly empty. The components are not broken up in
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smaller parts (for example, the network location is a single string), and %
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escapes are not expanded. The delimiters as shown above are not part of the
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result, except for a leading slash in the *path* component, which is retained if
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present. For example:
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>>> from urllib.parse import urlparse
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>>> o = urlparse('http://www.cwi.nl:80/%7Eguido/Python.html')
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>>> o # doctest: +NORMALIZE_WHITESPACE
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ParseResult(scheme='http', netloc='www.cwi.nl:80', path='/%7Eguido/Python.html',
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params='', query='', fragment='')
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>>> o.scheme
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'http'
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>>> o.port
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80
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>>> o.geturl()
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'http://www.cwi.nl:80/%7Eguido/Python.html'
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If the *default_scheme* argument is specified, it gives the default addressing
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scheme, to be used only if the URL does not specify one. The default value for
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this argument is the empty string.
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If the *allow_fragments* argument is false, fragment identifiers are not
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allowed, even if the URL's addressing scheme normally does support them. The
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default value for this argument is :const:`True`.
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The return value is actually an instance of a subclass of :class:`tuple`. This
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class has the following additional read-only convenience attributes:
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+------------------+-------+--------------------------+----------------------+
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| Attribute | Index | Value | Value if not present |
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+==================+=======+==========================+======================+
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| :attr:`scheme` | 0 | URL scheme specifier | empty string |
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+------------------+-------+--------------------------+----------------------+
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| :attr:`netloc` | 1 | Network location part | empty string |
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+------------------+-------+--------------------------+----------------------+
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| :attr:`path` | 2 | Hierarchical path | empty string |
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+------------------+-------+--------------------------+----------------------+
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| :attr:`params` | 3 | Parameters for last path | empty string |
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| | | element | |
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+------------------+-------+--------------------------+----------------------+
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| :attr:`query` | 4 | Query component | empty string |
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+------------------+-------+--------------------------+----------------------+
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| :attr:`fragment` | 5 | Fragment identifier | empty string |
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+------------------+-------+--------------------------+----------------------+
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| :attr:`username` | | User name | :const:`None` |
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+------------------+-------+--------------------------+----------------------+
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| :attr:`password` | | Password | :const:`None` |
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+------------------+-------+--------------------------+----------------------+
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| :attr:`hostname` | | Host name (lower case) | :const:`None` |
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+------------------+-------+--------------------------+----------------------+
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| :attr:`port` | | Port number as integer, | :const:`None` |
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| | | if present | |
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+------------------+-------+--------------------------+----------------------+
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See section :ref:`urlparse-result-object` for more information on the result
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object.
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.. function:: urlunparse(parts)
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Construct a URL from a tuple as returned by ``urlparse()``. The *parts*
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argument can be any six-item iterable. This may result in a slightly
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different, but equivalent URL, if the URL that was parsed originally had
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unnecessary delimiters (for example, a ``?`` with an empty query; the RFC
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states that these are equivalent).
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.. function:: urlsplit(urlstring[, default_scheme[, allow_fragments]])
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This is similar to :func:`urlparse`, but does not split the params from the URL.
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This should generally be used instead of :func:`urlparse` if the more recent URL
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syntax allowing parameters to be applied to each segment of the *path* portion
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of the URL (see :rfc:`2396`) is wanted. A separate function is needed to
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separate the path segments and parameters. This function returns a 5-tuple:
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(addressing scheme, network location, path, query, fragment identifier).
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The return value is actually an instance of a subclass of :class:`tuple`. This
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class has the following additional read-only convenience attributes:
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+------------------+-------+-------------------------+----------------------+
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| Attribute | Index | Value | Value if not present |
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+==================+=======+=========================+======================+
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| :attr:`scheme` | 0 | URL scheme specifier | empty string |
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+------------------+-------+-------------------------+----------------------+
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| :attr:`netloc` | 1 | Network location part | empty string |
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+------------------+-------+-------------------------+----------------------+
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| :attr:`path` | 2 | Hierarchical path | empty string |
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+------------------+-------+-------------------------+----------------------+
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| :attr:`query` | 3 | Query component | empty string |
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+------------------+-------+-------------------------+----------------------+
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| :attr:`fragment` | 4 | Fragment identifier | empty string |
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+------------------+-------+-------------------------+----------------------+
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| :attr:`username` | | User name | :const:`None` |
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+------------------+-------+-------------------------+----------------------+
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| :attr:`password` | | Password | :const:`None` |
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+------------------+-------+-------------------------+----------------------+
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| :attr:`hostname` | | Host name (lower case) | :const:`None` |
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+------------------+-------+-------------------------+----------------------+
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| :attr:`port` | | Port number as integer, | :const:`None` |
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| | | if present | |
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+------------------+-------+-------------------------+----------------------+
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See section :ref:`urlparse-result-object` for more information on the result
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object.
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.. function:: urlunsplit(parts)
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Combine the elements of a tuple as returned by :func:`urlsplit` into a
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complete URL as a string. The *parts* argument can be any five-item
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iterable. This may result in a slightly different, but equivalent URL, if the
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URL that was parsed originally had unnecessary delimiters (for example, a ?
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with an empty query; the RFC states that these are equivalent).
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.. function:: urljoin(base, url[, allow_fragments])
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Construct a full ("absolute") URL by combining a "base URL" (*base*) with
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another URL (*url*). Informally, this uses components of the base URL, in
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particular the addressing scheme, the network location and (part of) the
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path, to provide missing components in the relative URL. For example:
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>>> from urllib.parse import urljoin
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>>> urljoin('http://www.cwi.nl/%7Eguido/Python.html', 'FAQ.html')
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'http://www.cwi.nl/%7Eguido/FAQ.html'
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The *allow_fragments* argument has the same meaning and default as for
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:func:`urlparse`.
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.. note::
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If *url* is an absolute URL (that is, starting with ``//`` or ``scheme://``),
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the *url*'s host name and/or scheme will be present in the result. For example:
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.. doctest::
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>>> urljoin('http://www.cwi.nl/%7Eguido/Python.html',
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... '//www.python.org/%7Eguido')
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'http://www.python.org/%7Eguido'
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If you do not want that behavior, preprocess the *url* with :func:`urlsplit` and
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:func:`urlunsplit`, removing possible *scheme* and *netloc* parts.
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.. function:: urldefrag(url)
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If *url* contains a fragment identifier, return a modified version of *url*
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with no fragment identifier, and the fragment identifier as a separate
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string. If there is no fragment identifier in *url*, return *url* unmodified
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and an empty string.
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.. function:: quote(string[, safe[, encoding[, errors]]])
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Replace special characters in *string* using the ``%xx`` escape. Letters,
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digits, and the characters ``'_.-'`` are never quoted. The optional *safe*
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parameter specifies additional ASCII characters that should not be quoted
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--- its default value is ``'/'``.
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*string* may be either a :class:`str` or a :class:`bytes`.
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The optional *encoding* and *errors* parameters specify how to deal with
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non-ASCII characters, as accepted by the :meth:`str.encode` method.
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*encoding* defaults to ``'utf-8'``.
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*errors* defaults to ``'strict'``, meaning unsupported characters raise a
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:class:`UnicodeEncodeError`.
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*encoding* and *errors* must not be supplied if *string* is a
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:class:`bytes`, or a :class:`TypeError` is raised.
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Note that ``quote(string, safe, encoding, errors)`` is equivalent to
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``quote_from_bytes(string.encode(encoding, errors), safe)``.
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Example: ``quote('/El Niño/')`` yields ``'/El%20Ni%C3%B1o/'``.
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.. function:: quote_plus(string[, safe[, encoding[, errors]]])
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Like :func:`quote`, but also replace spaces by plus signs, as required for
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quoting HTML form values. Plus signs in the original string are escaped
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unless they are included in *safe*. It also does not have *safe* default to
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``'/'``.
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Example: ``quote_plus('/El Niño/')`` yields ``'%2FEl+Ni%C3%B1o%2F'``.
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.. function:: quote_from_bytes(bytes[, safe])
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Like :func:`quote`, but accepts a :class:`bytes` object rather than a
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:class:`str`, and does not perform string-to-bytes encoding.
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Example: ``quote_from_bytes(b'a&\xef')`` yields
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``'a%26%EF'``.
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.. function:: unquote(string[, encoding[, errors]])
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Replace ``%xx`` escapes by their single-character equivalent.
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The optional *encoding* and *errors* parameters specify how to decode
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percent-encoded sequences into Unicode characters, as accepted by the
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:meth:`bytes.decode` method.
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*string* must be a :class:`str`.
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*encoding* defaults to ``'utf-8'``.
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*errors* defaults to ``'replace'``, meaning invalid sequences are replaced
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by a placeholder character.
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Example: ``unquote('/El%20Ni%C3%B1o/')`` yields ``'/El Niño/'``.
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.. function:: unquote_plus(string[, encoding[, errors]])
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Like :func:`unquote`, but also replace plus signs by spaces, as required for
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unquoting HTML form values.
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*string* must be a :class:`str`.
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Example: ``unquote_plus('/El+Ni%C3%B1o/')`` yields ``'/El Niño/'``.
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.. function:: unquote_to_bytes(string)
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Replace ``%xx`` escapes by their single-octet equivalent, and return a
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:class:`bytes` object.
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*string* may be either a :class:`str` or a :class:`bytes`.
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If it is a :class:`str`, unescaped non-ASCII characters in *string*
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are encoded into UTF-8 bytes.
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Example: ``unquote_to_bytes('a%26%EF')`` yields
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``b'a&\xef'``.
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.. function:: urlencode(query[, doseq])
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Convert a mapping object or a sequence of two-element tuples to a "url-encoded"
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string, suitable to pass to :func:`urlopen` above as the optional *data*
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argument. This is useful to pass a dictionary of form fields to a ``POST``
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request. The resulting string is a series of ``key=value`` pairs separated by
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``'&'`` characters, where both *key* and *value* are quoted using
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:func:`quote_plus` above. If the optional parameter *doseq* is present and
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evaluates to true, individual ``key=value`` pairs are generated for each element
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of the sequence. When a sequence of two-element tuples is used as the *query*
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argument, the first element of each tuple is a key and the second is a value.
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The order of parameters in the encoded string will match the order of parameter
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tuples in the sequence. The :mod:`cgi` module provides the functions
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:func:`parse_qs` and :func:`parse_qsl` which are used to parse query strings
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into Python data structures.
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.. seealso::
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:rfc:`1738` - Uniform Resource Locators (URL)
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This specifies the formal syntax and semantics of absolute URLs.
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:rfc:`1808` - Relative Uniform Resource Locators
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This Request For Comments includes the rules for joining an absolute and a
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relative URL, including a fair number of "Abnormal Examples" which govern the
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treatment of border cases.
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:rfc:`2396` - Uniform Resource Identifiers (URI): Generic Syntax
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Document describing the generic syntactic requirements for both Uniform Resource
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Names (URNs) and Uniform Resource Locators (URLs).
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.. _urlparse-result-object:
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Results of :func:`urlparse` and :func:`urlsplit`
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------------------------------------------------
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The result objects from the :func:`urlparse` and :func:`urlsplit` functions are
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subclasses of the :class:`tuple` type. These subclasses add the attributes
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described in those functions, as well as provide an additional method:
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.. method:: ParseResult.geturl()
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Return the re-combined version of the original URL as a string. This may differ
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from the original URL in that the scheme will always be normalized to lower case
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and empty components may be dropped. Specifically, empty parameters, queries,
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and fragment identifiers will be removed.
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The result of this method is a fixpoint if passed back through the original
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parsing function:
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>>> import urllib.parse
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>>> url = 'HTTP://www.Python.org/doc/#'
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>>> r1 = urllib.parse.urlsplit(url)
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>>> r1.geturl()
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'http://www.Python.org/doc/'
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>>> r2 = urllib.parse.urlsplit(r1.geturl())
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>>> r2.geturl()
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'http://www.Python.org/doc/'
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The following classes provide the implementations of the parse results::
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.. class:: BaseResult
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Base class for the concrete result classes. This provides most of the
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attribute definitions. It does not provide a :meth:`geturl` method. It is
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derived from :class:`tuple`, but does not override the :meth:`__init__` or
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:meth:`__new__` methods.
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.. class:: ParseResult(scheme, netloc, path, params, query, fragment)
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Concrete class for :func:`urlparse` results. The :meth:`__new__` method is
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overridden to support checking that the right number of arguments are passed.
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.. class:: SplitResult(scheme, netloc, path, query, fragment)
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Concrete class for :func:`urlsplit` results. The :meth:`__new__` method is
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overridden to support checking that the right number of arguments are passed.
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