
``urllib.parse`` --- Parse URLs into components
***********************************************

This module defines a standard interface to break Uniform Resource
Locator (URL) strings up in components (addressing scheme, network
location, path etc.), to combine the components back into a URL
string, and to convert a "relative URL" to an absolute URL given a
"base URL."

The module has been designed to match the Internet RFC on Relative
Uniform Resource Locators (and discovered a bug in an earlier draft!).
It supports the following URL schemes: ``file``, ``ftp``, ``gopher``,
``hdl``, ``http``, ``https``, ``imap``, ``mailto``, ``mms``, ``news``,
``nntp``, ``prospero``, ``rsync``, ``rtsp``, ``rtspu``, ``sftp``,
``shttp``, ``sip``, ``sips``, ``snews``, ``svn``, ``svn+ssh``,
``telnet``, ``wais``.

The ``urllib.parse`` module defines functions that fall into two broad
categories: URL parsing and URL quoting. These are covered in detail
in the following sections.


URL Parsing
===========

The URL parsing functions focus on splitting a URL string into its
components, or on combining URL components into a URL string.

urllib.parse.urlparse(urlstring, scheme='', allow_fragments=True)

   Parse a URL into six components, returning a 6-tuple.  This
   corresponds to the general structure of a URL:
   ``scheme://netloc/path;parameters?query#fragment``. Each tuple item
   is a string, possibly empty. The components are not broken up in
   smaller parts (for example, the network location is a single
   string), and % escapes are not expanded. The delimiters as shown
   above are not part of the result, except for a leading slash in the
   *path* component, which is retained if present.  For example:

   >>> from urllib.parse import urlparse
   >>> o = urlparse('http://www.cwi.nl:80/%7Eguido/Python.html')
   >>> o   # doctest: +NORMALIZE_WHITESPACE
   ParseResult(scheme='http', netloc='www.cwi.nl:80', path='/%7Eguido/Python.html',
               params='', query='', fragment='')
   >>> o.scheme
   'http'
   >>> o.port
   80
   >>> o.geturl()
   'http://www.cwi.nl:80/%7Eguido/Python.html'

   Following the syntax specifications in **RFC 1808**, urlparse
   recognizes a netloc only if it is properly introduced by '//'.
   Otherwise the input is presumed to be a relative URL and thus to
   start with a path component.

   >>> from urllib.parse import urlparse
   >>> urlparse('//www.cwi.nl:80/%7Eguido/Python.html')
   ParseResult(scheme='', netloc='www.cwi.nl:80', path='/%7Eguido/Python.html',
              params='', query='', fragment='')
   >>> urlparse('www.cwi.nl:80/%7Eguido/Python.html')
   ParseResult(scheme='', netloc='', path='www.cwi.nl:80/%7Eguido/Python.html',
              params='', query='', fragment='')
   >>> urlparse('help/Python.html')
   ParseResult(scheme='', netloc='', path='help/Python.html', params='',
              query='', fragment='')

   If the *scheme* argument is specified, it gives the default
   addressing scheme, to be used only if the URL does not specify one.
   The default value for this argument is the empty string.

   If the *allow_fragments* argument is false, fragment identifiers
   are not allowed, even if the URL's addressing scheme normally does
   support them.  The default value for this argument is ``True``.

   The return value is actually an instance of a subclass of
   ``tuple``.  This class has the following additional read-only
   convenience attributes:

   +--------------------+---------+----------------------------+------------------------+
   | Attribute          | Index   | Value                      | Value if not present   |
   +====================+=========+============================+========================+
   | ``scheme``         | 0       | URL scheme specifier       | empty string           |
   +--------------------+---------+----------------------------+------------------------+
   | ``netloc``         | 1       | Network location part      | empty string           |
   +--------------------+---------+----------------------------+------------------------+
   | ``path``           | 2       | Hierarchical path          | empty string           |
   +--------------------+---------+----------------------------+------------------------+
   | ``params``         | 3       | Parameters for last path   | empty string           |
   |                    |         | element                    |                        |
   +--------------------+---------+----------------------------+------------------------+
   | ``query``          | 4       | Query component            | empty string           |
   +--------------------+---------+----------------------------+------------------------+
   | ``fragment``       | 5       | Fragment identifier        | empty string           |
   +--------------------+---------+----------------------------+------------------------+
   | ``username``       |         | User name                  | ``None``               |
   +--------------------+---------+----------------------------+------------------------+
   | ``password``       |         | Password                   | ``None``               |
   +--------------------+---------+----------------------------+------------------------+
   | ``hostname``       |         | Host name (lower case)     | ``None``               |
   +--------------------+---------+----------------------------+------------------------+
   | ``port``           |         | Port number as integer, if | ``None``               |
   |                    |         | present                    |                        |
   +--------------------+---------+----------------------------+------------------------+

   See section *Structured Parse Results* for more information on the
   result object.

   Changed in version 3.2: Added IPv6 URL parsing capabilities.

urllib.parse.parse_qs(qs, keep_blank_values=False, strict_parsing=False, encoding='utf-8', errors='replace')

   Parse a query string given as a string argument (data of type
   *application/x-www-form-urlencoded*).  Data are returned as a
   dictionary.  The dictionary keys are the unique query variable
   names and the values are lists of values for each name.

   The optional argument *keep_blank_values* is a flag indicating
   whether blank values in percent-encoded queries should be treated
   as blank strings. A true value indicates that blanks should be
   retained as  blank strings.  The default false value indicates that
   blank values are to be ignored and treated as if they were not
   included.

   The optional argument *strict_parsing* is a flag indicating what to
   do with parsing errors.  If false (the default), errors are
   silently ignored.  If true, errors raise a ``ValueError``
   exception.

   The optional *encoding* and *errors* parameters specify how to
   decode percent-encoded sequences into Unicode characters, as
   accepted by the ``bytes.decode()`` method.

   Use the ``urllib.parse.urlencode()`` function to convert such
   dictionaries into query strings.

   Changed in version 3.2: Add *encoding* and *errors* parameters.

urllib.parse.parse_qsl(qs, keep_blank_values=False, strict_parsing=False, encoding='utf-8', errors='replace')

   Parse a query string given as a string argument (data of type
   *application/x-www-form-urlencoded*).  Data are returned as a list
   of name, value pairs.

   The optional argument *keep_blank_values* is a flag indicating
   whether blank values in percent-encoded queries should be treated
   as blank strings. A true value indicates that blanks should be
   retained as  blank strings.  The default false value indicates that
   blank values are to be ignored and treated as if they were not
   included.

   The optional argument *strict_parsing* is a flag indicating what to
   do with parsing errors.  If false (the default), errors are
   silently ignored.  If true, errors raise a ``ValueError``
   exception.

   The optional *encoding* and *errors* parameters specify how to
   decode percent-encoded sequences into Unicode characters, as
   accepted by the ``bytes.decode()`` method.

   Use the ``urllib.parse.urlencode()`` function to convert such lists
   of pairs into query strings.

   Changed in version 3.2: Add *encoding* and *errors* parameters.

urllib.parse.urlunparse(parts)

   Construct a URL from a tuple as returned by ``urlparse()``. The
   *parts* argument can be any six-item iterable. This may result in a
   slightly different, but equivalent URL, if the URL that was parsed
   originally had unnecessary delimiters (for example, a ``?`` with an
   empty query; the RFC states that these are equivalent).

urllib.parse.urlsplit(urlstring, scheme='', allow_fragments=True)

   This is similar to ``urlparse()``, but does not split the params
   from the URL. This should generally be used instead of
   ``urlparse()`` if the more recent URL syntax allowing parameters to
   be applied to each segment of the *path* portion of the URL (see
   **RFC 2396**) is wanted.  A separate function is needed to separate
   the path segments and parameters.  This function returns a 5-tuple:
   (addressing scheme, network location, path, query, fragment
   identifier).

   The return value is actually an instance of a subclass of
   ``tuple``.  This class has the following additional read-only
   convenience attributes:

   +--------------------+---------+---------------------------+------------------------+
   | Attribute          | Index   | Value                     | Value if not present   |
   +====================+=========+===========================+========================+
   | ``scheme``         | 0       | URL scheme specifier      | empty string           |
   +--------------------+---------+---------------------------+------------------------+
   | ``netloc``         | 1       | Network location part     | empty string           |
   +--------------------+---------+---------------------------+------------------------+
   | ``path``           | 2       | Hierarchical path         | empty string           |
   +--------------------+---------+---------------------------+------------------------+
   | ``query``          | 3       | Query component           | empty string           |
   +--------------------+---------+---------------------------+------------------------+
   | ``fragment``       | 4       | Fragment identifier       | empty string           |
   +--------------------+---------+---------------------------+------------------------+
   | ``username``       |         | User name                 | ``None``               |
   +--------------------+---------+---------------------------+------------------------+
   | ``password``       |         | Password                  | ``None``               |
   +--------------------+---------+---------------------------+------------------------+
   | ``hostname``       |         | Host name (lower case)    | ``None``               |
   +--------------------+---------+---------------------------+------------------------+
   | ``port``           |         | Port number as integer,   | ``None``               |
   |                    |         | if present                |                        |
   +--------------------+---------+---------------------------+------------------------+

   See section *Structured Parse Results* for more information on the
   result object.

urllib.parse.urlunsplit(parts)

   Combine the elements of a tuple as returned by ``urlsplit()`` into
   a complete URL as a string. The *parts* argument can be any five-
   item iterable. This may result in a slightly different, but
   equivalent URL, if the URL that was parsed originally had
   unnecessary delimiters (for example, a ? with an empty query; the
   RFC states that these are equivalent).

urllib.parse.urljoin(base, url, allow_fragments=True)

   Construct a full ("absolute") URL by combining a "base URL"
   (*base*) with another URL (*url*).  Informally, this uses
   components of the base URL, in particular the addressing scheme,
   the network location and (part of) the path, to provide missing
   components in the relative URL.  For example:

   >>> from urllib.parse import urljoin
   >>> urljoin('http://www.cwi.nl/%7Eguido/Python.html', 'FAQ.html')
   'http://www.cwi.nl/%7Eguido/FAQ.html'

   The *allow_fragments* argument has the same meaning and default as
   for ``urlparse()``.

   Note: If *url* is an absolute URL (that is, starting with ``//`` or
     ``scheme://``), the *url*'s host name and/or scheme will be
     present in the result.  For example:

      >>> urljoin('http://www.cwi.nl/%7Eguido/Python.html',
      ...         '//www.python.org/%7Eguido')
      'http://www.python.org/%7Eguido'

   If you do not want that behavior, preprocess the *url* with
   ``urlsplit()`` and ``urlunsplit()``, removing possible *scheme* and
   *netloc* parts.

urllib.parse.urldefrag(url)

   If *url* contains a fragment identifier, return a modified version
   of *url* with no fragment identifier, and the fragment identifier
   as a separate string.  If there is no fragment identifier in *url*,
   return *url* unmodified and an empty string.

   The return value is actually an instance of a subclass of
   ``tuple``.  This class has the following additional read-only
   convenience attributes:

   +--------------------+---------+---------------------------+------------------------+
   | Attribute          | Index   | Value                     | Value if not present   |
   +====================+=========+===========================+========================+
   | ``url``            | 0       | URL with no fragment      | empty string           |
   +--------------------+---------+---------------------------+------------------------+
   | ``fragment``       | 1       | Fragment identifier       | empty string           |
   +--------------------+---------+---------------------------+------------------------+

   See section *Structured Parse Results* for more information on the
   result object.

   Changed in version 3.2: Result is a structured object rather than a
   simple 2-tuple.


Parsing ASCII Encoded Bytes
===========================

The URL parsing functions were originally designed to operate on
character strings only. In practice, it is useful to be able to
manipulate properly quoted and encoded URLs as sequences of ASCII
bytes. Accordingly, the URL parsing functions in this module all
operate on ``bytes`` and ``bytearray`` objects in addition to ``str``
objects.

If ``str`` data is passed in, the result will also contain only
``str`` data. If ``bytes`` or ``bytearray`` data is passed in, the
result will contain only ``bytes`` data.

Attempting to mix ``str`` data with ``bytes`` or ``bytearray`` in a
single function call will result in a ``TypeError`` being raised,
while attempting to pass in non-ASCII byte values will trigger
``UnicodeDecodeError``.

To support easier conversion of result objects between ``str`` and
``bytes``, all return values from URL parsing functions provide either
an ``encode()`` method (when the result contains ``str`` data) or a
``decode()`` method (when the result contains ``bytes`` data). The
signatures of these methods match those of the corresponding ``str``
and ``bytes`` methods (except that the default encoding is ``'ascii'``
rather than ``'utf-8'``). Each produces a value of a corresponding
type that contains either ``bytes`` data (for ``encode()`` methods) or
``str`` data (for ``decode()`` methods).

Applications that need to operate on potentially improperly quoted
URLs that may contain non-ASCII data will need to do their own
decoding from bytes to characters before invoking the URL parsing
methods.

The behaviour described in this section applies only to the URL
parsing functions. The URL quoting functions use their own rules when
producing or consuming byte sequences as detailed in the documentation
of the individual URL quoting functions.

Changed in version 3.2: URL parsing functions now accept ASCII encoded
byte sequences


Structured Parse Results
========================

The result objects from the ``urlparse()``, ``urlsplit()``  and
``urldefrag()`` functions are subclasses of the ``tuple`` type. These
subclasses add the attributes listed in the documentation for those
functions, the encoding and decoding support described in the previous
section, as well as an additional method:

urllib.parse.SplitResult.geturl()

   Return the re-combined version of the original URL as a string.
   This may differ from the original URL in that the scheme may be
   normalized to lower case and empty components may be dropped.
   Specifically, empty parameters, queries, and fragment identifiers
   will be removed.

   For ``urldefrag()`` results, only empty fragment identifiers will
   be removed. For ``urlsplit()`` and ``urlparse()`` results, all
   noted changes will be made to the URL returned by this method.

   The result of this method remains unchanged if passed back through
   the original parsing function:

   >>> from urllib.parse import urlsplit
   >>> url = 'HTTP://www.Python.org/doc/#'
   >>> r1 = urlsplit(url)
   >>> r1.geturl()
   'http://www.Python.org/doc/'
   >>> r2 = urlsplit(r1.geturl())
   >>> r2.geturl()
   'http://www.Python.org/doc/'

The following classes provide the implementations of the structured
parse results when operating on ``str`` objects:

class class urllib.parse.DefragResult(url, fragment)

   Concrete class for ``urldefrag()`` results containing ``str`` data.
   The ``encode()`` method returns a ``DefragResultBytes`` instance.

   New in version 3.2.

class class urllib.parse.ParseResult(scheme, netloc, path, params, query, fragment)

   Concrete class for ``urlparse()`` results containing ``str`` data.
   The ``encode()`` method returns a ``ParseResultBytes`` instance.

class class urllib.parse.SplitResult(scheme, netloc, path, query, fragment)

   Concrete class for ``urlsplit()`` results containing ``str`` data.
   The ``encode()`` method returns a ``SplitResultBytes`` instance.

The following classes provide the implementations of the parse results
when operating on ``bytes`` or ``bytearray`` objects:

class class urllib.parse.DefragResultBytes(url, fragment)

   Concrete class for ``urldefrag()`` results containing ``bytes``
   data. The ``decode()`` method returns a ``DefragResult`` instance.

   New in version 3.2.

class class urllib.parse.ParseResultBytes(scheme, netloc, path, params, query, fragment)

   Concrete class for ``urlparse()`` results containing ``bytes``
   data. The ``decode()`` method returns a ``ParseResult`` instance.

   New in version 3.2.

class class urllib.parse.SplitResultBytes(scheme, netloc, path, query, fragment)

   Concrete class for ``urlsplit()`` results containing ``bytes``
   data. The ``decode()`` method returns a ``SplitResult`` instance.

   New in version 3.2.


URL Quoting
===========

The URL quoting functions focus on taking program data and making it
safe for use as URL components by quoting special characters and
appropriately encoding non-ASCII text. They also support reversing
these operations to recreate the original data from the contents of a
URL component if that task isn't already covered by the URL parsing
functions above.

urllib.parse.quote(string, safe='/', encoding=None, errors=None)

   Replace special characters in *string* using the ``%xx`` escape.
   Letters, digits, and the characters ``'_.-'`` are never quoted. By
   default, this function is intended for quoting the path section of
   URL. The optional *safe* parameter specifies additional ASCII
   characters that should not be quoted --- its default value is
   ``'/'``.

   *string* may be either a ``str`` or a ``bytes``.

   The optional *encoding* and *errors* parameters specify how to deal
   with non-ASCII characters, as accepted by the ``str.encode()``
   method. *encoding* defaults to ``'utf-8'``. *errors* defaults to
   ``'strict'``, meaning unsupported characters raise a
   ``UnicodeEncodeError``. *encoding* and *errors* must not be
   supplied if *string* is a ``bytes``, or a ``TypeError`` is raised.

   Note that ``quote(string, safe, encoding, errors)`` is equivalent
   to ``quote_from_bytes(string.encode(encoding, errors), safe)``.

   Example: ``quote('/El Niño/')`` yields ``'/El%20Ni%C3%B1o/'``.

urllib.parse.quote_plus(string, safe='', encoding=None, errors=None)

   Like ``quote()``, but also replace spaces by plus signs, as
   required for quoting HTML form values when building up a query
   string to go into a URL. Plus signs in the original string are
   escaped unless they are included in *safe*.  It also does not have
   *safe* default to ``'/'``.

   Example: ``quote_plus('/El Niño/')`` yields
   ``'%2FEl+Ni%C3%B1o%2F'``.

urllib.parse.quote_from_bytes(bytes, safe='/')

   Like ``quote()``, but accepts a ``bytes`` object rather than a
   ``str``, and does not perform string-to-bytes encoding.

   Example: ``quote_from_bytes(b'a&\xef')`` yields ``'a%26%EF'``.

urllib.parse.unquote(string, encoding='utf-8', errors='replace')

   Replace ``%xx`` escapes by their single-character equivalent. The
   optional *encoding* and *errors* parameters specify how to decode
   percent-encoded sequences into Unicode characters, as accepted by
   the ``bytes.decode()`` method.

   *string* must be a ``str``.

   *encoding* defaults to ``'utf-8'``. *errors* defaults to
   ``'replace'``, meaning invalid sequences are replaced by a
   placeholder character.

   Example: ``unquote('/El%20Ni%C3%B1o/')`` yields ``'/El Niño/'``.

urllib.parse.unquote_plus(string, encoding='utf-8', errors='replace')

   Like ``unquote()``, but also replace plus signs by spaces, as
   required for unquoting HTML form values.

   *string* must be a ``str``.

   Example: ``unquote_plus('/El+Ni%C3%B1o/')`` yields ``'/El Niño/'``.

urllib.parse.unquote_to_bytes(string)

   Replace ``%xx`` escapes by their single-octet equivalent, and
   return a ``bytes`` object.

   *string* may be either a ``str`` or a ``bytes``.

   If it is a ``str``, unescaped non-ASCII characters in *string* are
   encoded into UTF-8 bytes.

   Example: ``unquote_to_bytes('a%26%EF')`` yields ``b'a&\xef'``.

urllib.parse.urlencode(query, doseq=False, safe='', encoding=None, errors=None)

   Convert a mapping object or a sequence of two-element tuples, which
   may either be a ``str`` or a ``bytes``,  to a "percent-encoded"
   string.  The resultant string must be converted to bytes using the
   user-specified encoding before it is sent to ``urlopen()`` as the
   optional *data* argument. The resulting string is a series of
   ``key=value`` pairs separated by ``'&'`` characters, where both
   *key* and *value* are quoted using ``quote_plus()`` above. When a
   sequence of two-element tuples is used as the *query* argument, the
   first element of each tuple is a key and the second is a value. The
   value element in itself can be a sequence and in that case, if the
   optional parameter *doseq* is evaluates to *True*, individual
   ``key=value`` pairs separated by ``'&'`` are generated for each
   element of the value sequence for the key.  The order of parameters
   in the encoded string will match the order of parameter tuples in
   the sequence.

   When *query* parameter is a ``str``, the *safe*, *encoding* and
   *error* parameters are passed down to ``quote_plus()`` for
   encoding.

   To reverse this encoding process, ``parse_qs()`` and
   ``parse_qsl()`` are provided in this module to parse query strings
   into Python data structures.

   Refer to *urllib examples* to find out how urlencode method can be
   used for generating query string for a URL or data for POST.

   Changed in version 3.2: Query parameter supports bytes and string
   objects.

See also:

   **RFC 3986** - Uniform Resource Identifiers
      This is the current standard (STD66). Any changes to
      urllib.parse module should conform to this. Certain deviations
      could be observed, which are mostly for backward compatibility
      purposes and for certain de-facto parsing requirements as
      commonly observed in major browsers.

   **RFC 2732** - Format for Literal IPv6 Addresses in URL's.
      This specifies the parsing requirements of IPv6 URLs.

   **RFC 2396** - Uniform Resource Identifiers (URI): Generic Syntax
      Document describing the generic syntactic requirements for both
      Uniform Resource Names (URNs) and Uniform Resource Locators
      (URLs).

   **RFC 2368** - The mailto URL scheme.
      Parsing requirements for mailto url schemes.

   **RFC 1808** - Relative Uniform Resource Locators
      This Request For Comments includes the rules for joining an
      absolute and a relative URL, including a fair number of
      "Abnormal Examples" which govern the treatment of border cases.

   **RFC 1738** - Uniform Resource Locators (URL)
      This specifies the formal syntax and semantics of absolute URLs.
