Doc/lib/liburlparse.tex

   1 \section{\module{urlparse} ---
   2          Parse URLs into components}
   3 \declaremodule{standard}{urlparse}
   4
   5 \modulesynopsis{Parse URLs into components.}
   6
   7 \index{WWW}
   8 \index{World Wide Web}
   9 \index{URL}
  10 \indexii{URL}{parsing}
  11 \indexii{relative}{URL}
  12
  13
  14 This module defines a standard interface to break Uniform Resource
  15 Locator (URL) strings up in components (addressing scheme, network
  16 location, path etc.), to combine the components back into a URL
  17 string, and to convert a ``relative URL'' to an absolute URL given a
  18 ``base URL.''
  19
  20 The module has been designed to match the Internet RFC on Relative
  21 Uniform Resource Locators (and discovered a bug in an earlier
  22 draft!).
  23
  24 It defines the following functions:
  25
  26 \begin{funcdesc}{urlparse}{urlstring\optional{, default_scheme\optional{, allow_fragments}}}
  27 Parse a URL into 6 components, returning a 6-tuple: (addressing
  28 scheme, network location, path, parameters, query, fragment
  29 identifier).  This corresponds to the general structure of a URL:
  30 \code{\var{scheme}://\var{netloc}/\var{path};\var{parameters}?\var{query}\#\var{fragment}}.
  31 Each tuple item is a string, possibly empty.
  32 The components are not broken up in smaller parts (e.g. the network
  33 location is a single string), and \% escapes are not expanded.
  34 The delimiters as shown above are not part of the tuple items,
  35 except for a leading slash in the \var{path} component, which is
  36 retained if present.
  37
  38 Example:
  39
  40 \begin{verbatim}
  41 urlparse('http://www.cwi.nl:80/%7Eguido/Python.html')
  42 \end{verbatim}
  43
  44 yields the tuple
  45
  46 \begin{verbatim}
  47 ('http', 'www.cwi.nl:80', '/%7Eguido/Python.html', '', '', '')
  48 \end{verbatim}
  49
  50 If the \var{default_scheme} argument is specified, it gives the
  51 default addressing scheme, to be used only if the URL string does not
  52 specify one.  The default value for this argument is the empty string.
  53
  54 If the \var{allow_fragments} argument is zero, fragment identifiers
  55 are not allowed, even if the URL's addressing scheme normally does
  56 support them.  The default value for this argument is \code{1}.
  57 \end{funcdesc}
  58
  59 \begin{funcdesc}{urlunparse}{tuple}
  60 Construct a URL string from a tuple as returned by \code{urlparse()}.
  61 This may result in a slightly different, but equivalent URL, if the
  62 URL that was parsed originally had redundant delimiters, e.g. a ? with
  63 an empty query (the draft states that these are equivalent).
  64 \end{funcdesc}
  65
  66 \begin{funcdesc}{urlsplit}{urlstring\optional{,
  67                            default_scheme\optional{, allow_fragments}}}
  68 This is similar to \function{urlparse()}, but does not split the
  69 params from the URL.  This should generally be used instead of
  70 \function{urlparse()} if the more recent URL syntax allowing
  71 parameters to be applied to each segment of the \var{path} portion of
  72 the URL (see \rfc{2396}).  A separate function is needed to separate
  73 the path segments and parameters.  This function returns a 5-tuple:
  74 (addressing scheme, network location, path, query, fragment
  75 identifier).
  76 \versionadded{2.2}
  77 \end{funcdesc}
  78
  79 \begin{funcdesc}{urlunsplit}{tuple}
  80 Combine the elements of a tuple as returned by \function{urlsplit()}
  81 into a complete URL as a string.
  82 \versionadded{2.2}
  83 \end{funcdesc}
  84
  85 \begin{funcdesc}{urljoin}{base, url\optional{, allow_fragments}}
  86 Construct a full (``absolute'') URL by combining a ``base URL''
  87 (\var{base}) with a ``relative URL'' (\var{url}).  Informally, this
  88 uses components of the base URL, in particular the addressing scheme,
  89 the network location and (part of) the path, to provide missing
  90 components in the relative URL.
  91
  92 Example:
  93
  94 \begin{verbatim}
  95 urljoin('http://www.cwi.nl/%7Eguido/Python.html', 'FAQ.html')
  96 \end{verbatim}
  97
  98 yields the string
  99
 100 \begin{verbatim}
 101 'http://www.cwi.nl/%7Eguido/FAQ.html'
 102 \end{verbatim}
 103
 104 The \var{allow_fragments} argument has the same meaning as for
 105 \code{urlparse()}.
 106 \end{funcdesc}
 107
 108 \begin{funcdesc}{urldefrag}{url}
 109 If \var{url} contains a fragment identifier, returns a modified
 110 version of \var{url} with no fragment identifier, and the fragment
 111 identifier as a separate string.  If there is no fragment identifier
 112 in \var{url}, returns \var{url} unmodified and an empty string.
 113 \end{funcdesc}
 114
 115
 116 \begin{seealso}
 117   \seerfc{1738}{Uniform Resource Locators (URL)}{
 118         This specifies the formal syntax and semantics of absolute
 119         URLs.}
 120   \seerfc{1808}{Relative Uniform Resource Locators}{
 121         This Request For Comments includes the rules for joining an
 122         absolute and a relative URL, including a fair number of
 123         ``Abnormal Examples'' which govern the treatment of border
 124         cases.}
 125   \seerfc{2396}{Uniform Resource Identifiers (URI): Generic Syntax}{
 126         Document describing the generic syntactic requirements for
 127         both Uniform Resource Names (URNs) and Uniform Resource
 128         Locators (URLs).}
 129 \end{seealso}