ncgi(n) 1.2.3 "CGI Support"
ncgi - Procedures to manipulate CGI values.
package require Tcl 8.2
package require ncgi ?1.2.3?
The 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
ncgi package to query these values, set and get cookies, and
encode and decode www-url-encoded values.
In the simplest case, a CGI script first calls ::ncgi::parse and
then calls ::ncgi::value to get different form values. If a CGI
value is repeated, you should use ::ncgi::valueList to get back
the complete list of values.
An alternative to ::ncgi::parse is ::ncgi::input, which
has semantics similar to Don Libes' cgi_input procedure.
::ncgi::input restricts repeated CGI values to have names that
end with "List". In this case, ::ncgi::value will return the
complete list of values, and ::ncgi::input will raise errors if
it find repeated form elements without the right name.
The ::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.
The complete set of procedures is described below.
- ::ncgi::cookie cookie
Return a list of values for cookie, if any. It is possible that
more than one cookie with the same name can be present, so this
procedure returns a list.
- ::ncgi::decode str
Decode strings in www-url-encoding, which represents special
characters with a %xx sequence, where xx is the character code in hex.
- ::ncgi::empty name
Returns 1 if the CGI variable name is not present or has the
empty string as its value.
- ::ncgi::encode string
Encode string into www-url-encoded format.
- ::ncgi::header ?type? args
Output the CGI header to standard output. This emits a Content-Type:
header and additional headers based on args, which is a list of
header names and header values. The type defaults to
- ::ncgi::import cginame ?tclname?
This creates a variable in the current scope with the value of the CGI
variable cginame. The name of the variable is tclname, or
cginame if tclname is empty (default).
- ::ncgi::importAll args
This imports several CGI variables as Tcl variables. If args is
empty, then every CGI value is imported. Otherwise each CGI variable
listed in args is imported.
- ::ncgi::importFile cmd cginame ?filename?
This provides information about an uploaded file from a form input
field of type file with name cginame. cmd can be
one of -server -client, -type or
- -client cginame
returns the filename as sent by the client.
- -type cginame
returns the mime type of the uploaded file.
- -data cginame
returns the contents of the file.
- -server cginame filename
writes the file contents to a local temporary file (or filename
if supplied) and returns the name of the file. The caller is
responsible for deleting this file after use.
- ::ncgi::input ?fakeinput? ?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 ::ncgi::value
- ::ncgi::multipart type query
This procedure parses a multipart/form-data query. This is used
by ::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 ::ncgi::value you just get the
form value. If you use ::ncgi::valueList you get the structured
value with meta data and the value.
The type is the whole Content-Type, including the parameters
like 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.
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
This reads and decodes the CGI values from the environment. The CGI
values are obtained later with the ::ncgi::value procedure. IF
a CGI value is repeated, then you should use ::ncgi::valueList
to get the complete list of values.
- ::ncgi::parseMimeValue 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.
This returns the raw query data.
- ::ncgi::redirect url
Generate a response that causes a 302 redirect by the Web server. The
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.
- ::ncgi::reset 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 query or type are
specified, then the ncgi module will look in the standard
CGI environment for its data.
- ::ncgi::setCookie args
Set a cookie value that will be returned as part of the reply. This
must be done before ::ncgi::header or ::ncgi::redirect is
called in order for the cookie to be returned properly. The
args are a set of flags and values:
- -name name
- -value value
- -expires date
- -path path restriction
- -domain domain restriction
- ::ncgi::setDefaultValue key defvalue
Set a CGI value if it does not already exists. This affects future
calls to ::ncgi::value (but not future calls to
::ncgi::nvlist). If the CGI value already is present, then this
procedure has no side effects.
- ::ncgi::setDefaultValueList key defvaluelist
Like ::ncgi::setDefaultValue except that the value already has
list structure to represent multiple checkboxes or a multi-selection.
- ::ncgi::setValue key value
Set a CGI value, overriding whatever was present in the CGI
environment already. This affects future calls to ::ncgi::value
(but not future calls to ::ncgi::nvlist).
- ::ncgi::setValueList key valuelist
Like ::ncgi::setValue except that the value already has list
structure to represent multiple checkboxes or a multi-selection.
Returns the Content-Type of the current CGI values.
- ::ncgi::urlStub ?url?
Returns the current URL, but without the protocol, server, and port.
If url is specified, then it defines the URL for the current
session. That value will be returned by future calls to
- ::ncgi::value key ?default?
Return the CGI value identified by key. If the CGI value is not
present, then the default value is returned instead. This value
defaults to the empty string.
If the form value key is repeated, then there are two cases: if
::ncgi::parse was called, then ::ncgi::value only returns
the first value associated with key. If ::ncgi::input was
called, then ::ncgi::value returns a Tcl list value and
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 ::ncgi::valueList.
- ::ncgi::valueList key ?default?
Like ::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.
CGI, cookie, form, html