path: root/tcllib/modules/ncgi/ncgi.man

[vset VERSION 1.4.3]
[manpage_begin ncgi n [vset VERSION]]
[see_also html]
[keywords CGI]
[keywords cookie]
[keywords form]
[keywords html]
[comment {-*- tcl -*- doctools manpage}]
[moddesc   {CGI Support}]
[titledesc {Procedures to manipulate CGI values.}]
[category  {CGI programming}]
[require Tcl 8.4]
[require ncgi [opt [vset VERSION]]]
[description]
[para]

The [package ncgi] package provides commands that manipulate CGI
values.  These are values that come from Web forms and are processed
either by CGI scripts or web pages with embedded Tcl code.  Use the
[package ncgi] package to query these values, set and get cookies, and
encode and decode www-url-encoded values.

[para]

In the simplest case, a CGI script first calls [cmd ::ncgi::parse] and
then calls [cmd ::ncgi::value] to get different form values.  If a CGI
value is repeated, you should use [cmd ::ncgi::valueList] to get back
the complete list of values.

[para]

An alternative to [cmd ::ncgi::parse] is [cmd ::ncgi::input], which
has semantics similar to Don Libes' [cmd cgi_input] procedure.

[cmd ::ncgi::input] restricts repeated CGI values to have names that
end with "List".  In this case, [cmd ::ncgi::value] will return the
complete list of values, and [cmd ::ncgi::input] will raise errors if
it find repeated form elements without the right name.

[para]

The [cmd ::ncgi::reset] procedure can be used in test suites and Web
servers to initialize the source of the CGI values.  Otherwise the
values are read in from the CGI environment.

[para]

The complete set of procedures is described below.

[list_begin definitions]

[call [cmd ::ncgi::cookie] [arg cookie]]

Return a list of values for [arg cookie], if any.  It is possible that
more than one cookie with the same name can be present, so this
procedure returns a list.

[call [cmd ::ncgi::decode] [arg str]]

Decode strings in www-url-encoding, which represents special
characters with a %xx sequence, where xx is the character code in hex.

[call [cmd ::ncgi::empty] [arg name]]

Returns 1 if the CGI variable [arg name] is not present or has the
empty string as its value.

[call [cmd ::ncgi::exists] [arg name]]

The return value is a boolean. It returns [const 0] if the CGI
variable [arg name] is not present, and [const 1] otherwise.

[call [cmd ::ncgi::encode] [arg string]]

Encode [arg string] into www-url-encoded format.

[call [cmd ::ncgi::header] [opt [arg type]] [arg args]]

Output the CGI header to standard output.  This emits a Content-Type:
header and additional headers based on [arg args], which is a list of
header names and header values. The [arg type] defaults to
"text/html".

[call [cmd ::ncgi::import] [arg cginame] [opt [arg tclname]]]

This creates a variable in the current scope with the value of the CGI
variable [arg cginame].  The name of the variable is [arg tclname], or
[arg cginame] if [arg tclname] is empty (default).

[call [cmd ::ncgi::importAll] [arg args]]

This imports several CGI variables as Tcl variables.  If [arg args] is
empty, then every CGI value is imported.  Otherwise each CGI variable
listed in [arg args] is imported.

[call [cmd ::ncgi::importFile] [arg cmd] [arg cginame] [opt [arg filename]]]

This provides information about an uploaded file from a form input
field of type [const file] with name [arg cginame].  [arg cmd] can be
one of [option -server] [option -client], [option -type] or
[option -data].

[list_begin definitions]

[def "[option -client] [arg cginame]"]

returns the filename as sent by the client.

[def "[option -type] [arg cginame]"]

returns the mime type of the uploaded file.

[def "[option -data] [arg cginame]"]

returns the contents of the file.

[def "[option -server] [arg cginame] [arg filename]"]

writes the file contents to a local temporary file (or [arg filename]
if supplied) and returns the name of the file. The caller is
responsible for deleting this file after use.

[list_end]

[call [cmd ::ncgi::input] [opt [arg fakeinput]] [opt [arg fakecookie]]]

This reads and decodes the CGI values from the environment.  It
restricts repeated form values to have a trailing "List" in their
name.  The CGI values are obtained later with the [cmd ::ncgi::value]
procedure.

[call [cmd ::ncgi::multipart] [arg {type query}]]

This procedure parses a multipart/form-data [arg query].  This is used
by [cmd ::ncgi::nvlist] and not normally called directly.  It returns
an alternating list of names and structured values.  Each structure
value is in turn a list of two elements.  The first element is
meta-data from the multipart/form-data structure.  The second element
is the form value.  If you use [cmd ::ncgi::value] you just get the
form value.  If you use [cmd ::ncgi::valueList] you get the structured
value with meta data and the value.

[para]

The [arg type] is the whole Content-Type, including the parameters
like [arg boundary].  This returns a list of names and values that
describe the multipart data.  The values are a nested list structure
that has some descriptive information first, and the actual form value
second.  The descriptive information is list of header names and
values that describe the content.

[call [cmd ::ncgi::nvlist]]

This returns all the query data as a name, value list.  In the case of
multipart/form-data, the values are structured as described in

[cmd ::ncgi::multipart].

[call [cmd ::ncgi::names]]

This returns all names found in the query data, as a list.

[cmd ::ncgi::multipart].

[call [cmd ::ncgi::parse]]

This reads and decodes the CGI values from the environment.  The CGI
values are obtained later with the [cmd ::ncgi::value] procedure.  IF
a CGI value is repeated, then you should use [cmd ::ncgi::valueList]
to get the complete list of values.

[call [cmd ::ncgi::parseMimeValue] [arg value]]

This decodes the Content-Type and other MIME headers that have the
form of "primary value; param=val; p2=v2" It returns a list, where the
first element is the primary value, and the second element is a list
of parameter names and values.

[call [cmd ::ncgi::query]]

This returns the raw query data.

[call [cmd ::ncgi::redirect] [arg url]]

Generate a response that causes a 302 redirect by the Web server.  The
[arg url] is the new URL that is the target of the redirect.  The URL
will be qualified with the current server and current directory, if
necessary, to convert it into a full URL.

[call [cmd ::ncgi::reset] [arg {query type}]]

Set the query data and Content-Type for the current CGI session.  This
is used by the test suite and by Web servers to initialize the ncgi
module so it does not try to read standard input or use environment
variables to get its data.  If neither [arg query] or [arg type] are
specified, then the [package ncgi] module will look in the standard
CGI environment for its data.

[call [cmd ::ncgi::setCookie] [arg args]]

Set a cookie value that will be returned as part of the reply.  This
must be done before [cmd ::ncgi::header] or [cmd ::ncgi::redirect] is
called in order for the cookie to be returned properly.  The

[arg args] are a set of flags and values:

[list_begin definitions]

[def "[option -name] [arg name]"]
[def "[option -value] [arg value]"]
[def "[option -expires] [arg date]"]
[def "[option -path] [arg {path restriction}]"]
[def "[option -domain] [arg {domain restriction}]"]
[list_end]

[call [cmd ::ncgi::setDefaultValue] [arg {key defvalue}]]

Set a CGI value if it does not already exists.  This affects future
calls to [cmd ::ncgi::value] (but not future calls to

[cmd ::ncgi::nvlist]).  If the CGI value already is present, then this
procedure has no side effects.

[call [cmd ::ncgi::setDefaultValueList] [arg {key defvaluelist}]]

Like [cmd ::ncgi::setDefaultValue] except that the value already has
list structure to represent multiple checkboxes or a multi-selection.

[call [cmd ::ncgi::setValue] [arg {key value}]]

Set a CGI value, overriding whatever was present in the CGI
environment already.  This affects future calls to [cmd ::ncgi::value]
(but not future calls to [cmd ::ncgi::nvlist]).

[call [cmd ::ncgi::setValueList] [arg {key valuelist}]]

Like [cmd ::ncgi::setValue] except that the value already has list
structure to represent multiple checkboxes or a multi-selection.

[call [cmd ::ncgi::type]]

Returns the Content-Type of the current CGI values.

[call [cmd ::ncgi::urlStub] [opt [arg url]]]

Returns the current URL, but without the protocol, server, and port.
If [arg url] is specified, then it defines the URL for the current
session.  That value will be returned by future calls to

[cmd ::ncgi::urlStub]

[call [cmd ::ncgi::value] [arg key] [opt [arg default]]]

Return the CGI value identified by [arg key].  If the CGI value is not
present, then the [arg default] value is returned instead. This value
defaults to the empty string.

[para]

If the form value [arg key] is repeated, then there are two cases: if
[cmd ::ncgi::parse] was called, then [cmd ::ncgi::value] only returns
the first value associated with [arg key].  If [cmd ::ncgi::input] was
called, then [cmd ::ncgi::value] returns a Tcl list value and

[arg key] must end in "List" (e.g., "skuList").  In the case of
multipart/form-data, this procedure just returns the value of the form
element.  If you want the meta-data associated with each form value,
then use [cmd ::ncgi::valueList].

[call [cmd ::ncgi::valueList] [arg key] [opt [arg default]]]

Like [cmd ::ncgi::value], but this always returns a list of values
(even if there is only one value).  In the case of
multipart/form-data, this procedure returns a list of two elements.
The first element is meta-data in the form of a parameter, value list.
The second element is the form value.

[list_end]

[section EXAMPLES]

Uploading a file
[example {
HTML:
<html>
<form action="/cgi-bin/upload.cgi" method="POST" enctype="multipart/form-data">
Path: <input type="file" name="filedata"><br>
Name: <input type="text" name="filedesc"><br>
<input type="submit">
</form>
</html>

TCL: upload.cgi
#!/usr/local/bin/tclsh

::ncgi::parse
set filedata [::ncgi::value filedata]
set filedesc [::ncgi::value filedesc]

puts "<html> File uploaded at <a href=\"/images/$filedesc\">$filedesc</a> </html>"

set filename /www/images/$filedesc

set fh [open $filename w]
puts -nonewline $fh $filedata
close $fh
}]

[para]

[vset CATEGORY ncgi]
[include ../doctools2base/include/feedback.inc]
[manpage_end]