cpython/Doc/library/cgi.rst

538 lines
22 KiB
ReStructuredText
Raw Normal View History

Merged revisions 73286,73294,73296,73459,73462-73463,73544,73576-73577,73595-73596,73693-73694,73704-73705,73707,73713,73937-73940,73945,73951,73979 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r73286 | georg.brandl | 2009-06-08 09:57:35 +0200 (Mo, 08 Jun 2009) | 1 line Remove period from end of headings. ........ r73294 | georg.brandl | 2009-06-08 15:34:52 +0200 (Mo, 08 Jun 2009) | 1 line #6194: O_SHLOCK/O_EXLOCK are not really more platform independent than lockf(). ........ r73296 | georg.brandl | 2009-06-08 18:03:41 +0200 (Mo, 08 Jun 2009) | 1 line #6238: add fillchar to string.just function family. ........ r73459 | raymond.hettinger | 2009-06-17 03:43:47 +0200 (Mi, 17 Jun 2009) | 1 line Add usage note. ........ r73462 | georg.brandl | 2009-06-17 11:36:21 +0200 (Mi, 17 Jun 2009) | 1 line #6295: clarify blocking behavior of getch(). ........ r73463 | georg.brandl | 2009-06-17 11:43:31 +0200 (Mi, 17 Jun 2009) | 1 line #6255: document PyInt_FromSize_t. ........ r73544 | georg.brandl | 2009-06-24 08:41:19 +0200 (Mi, 24 Jun 2009) | 1 line #6332: fix word dupes throughout the source. ........ r73576 | benjamin.peterson | 2009-06-27 01:37:06 +0200 (Sa, 27 Jun 2009) | 1 line document is_declared_global() ........ r73577 | benjamin.peterson | 2009-06-27 16:16:23 +0200 (Sa, 27 Jun 2009) | 1 line link to extensive generator docs in the reference manual ........ r73595 | ezio.melotti | 2009-06-28 01:45:39 +0200 (So, 28 Jun 2009) | 1 line stmt and setup can contain multiple statements, see #5896 ........ r73596 | ezio.melotti | 2009-06-28 02:07:45 +0200 (So, 28 Jun 2009) | 1 line Fixed a wrong apostrophe ........ r73693 | jesse.noller | 2009-06-29 20:20:34 +0200 (Mo, 29 Jun 2009) | 1 line Bug 5906: add a documentation note for unix daemons vs. multiprocessing daemons ........ r73694 | jesse.noller | 2009-06-29 20:24:26 +0200 (Mo, 29 Jun 2009) | 1 line Issue 5740: multiprocessing.connection.* authkey fixes ........ r73704 | georg.brandl | 2009-06-30 18:15:43 +0200 (Di, 30 Jun 2009) | 1 line #6376: fix copy-n-paste oversight. ........ r73705 | georg.brandl | 2009-06-30 18:17:28 +0200 (Di, 30 Jun 2009) | 1 line #6374: add a bit of explanation about shell=True on Windows. ........ r73707 | georg.brandl | 2009-06-30 18:35:11 +0200 (Di, 30 Jun 2009) | 1 line #6371: fix link targets. ........ r73713 | ezio.melotti | 2009-07-01 00:56:16 +0200 (Mi, 01 Jul 2009) | 1 line Fixed a backslash that was not supposed to be there ........ r73937 | georg.brandl | 2009-07-11 12:12:36 +0200 (Sa, 11 Jul 2009) | 1 line Fix style. ........ r73938 | georg.brandl | 2009-07-11 12:14:54 +0200 (Sa, 11 Jul 2009) | 1 line #6446: fix import_spam() function to use correct error and reference handling. ........ r73939 | georg.brandl | 2009-07-11 12:18:10 +0200 (Sa, 11 Jul 2009) | 1 line #6448: clarify docs for find_module(). ........ r73940 | georg.brandl | 2009-07-11 12:37:38 +0200 (Sa, 11 Jul 2009) | 1 line #6430: add note about size of "u" type. ........ r73945 | georg.brandl | 2009-07-11 12:51:31 +0200 (Sa, 11 Jul 2009) | 1 line #6456: clarify the meaning of constants used as arguments to nl_langinfo(). ........ r73951 | georg.brandl | 2009-07-11 16:23:38 +0200 (Sa, 11 Jul 2009) | 2 lines array.array is actually a class. ........ r73979 | benjamin.peterson | 2009-07-12 18:56:54 +0200 (So, 12 Jul 2009) | 1 line add versionadded ........
2009-10-27 11:29:22 -03:00
:mod:`cgi` --- Common Gateway Interface support
===============================================
2007-08-15 11:28:01 -03:00
.. module:: cgi
:synopsis: Helpers for running Python scripts via the Common Gateway Interface.
.. index::
pair: WWW; server
pair: CGI; protocol
pair: HTTP; protocol
pair: MIME; headers
single: URL
single: Common Gateway Interface
Support module for Common Gateway Interface (CGI) scripts.
This module defines a number of utilities for use by CGI scripts written in
Python.
Introduction
------------
.. _cgi-intro:
A CGI script is invoked by an HTTP server, usually to process user input
submitted through an HTML ``<FORM>`` or ``<ISINDEX>`` element.
Most often, CGI scripts live in the server's special :file:`cgi-bin` directory.
The HTTP server places all sorts of information about the request (such as the
client's hostname, the requested URL, the query string, and lots of other
goodies) in the script's shell environment, executes the script, and sends the
script's output back to the client.
The script's input is connected to the client too, and sometimes the form data
is read this way; at other times the form data is passed via the "query string"
part of the URL. This module is intended to take care of the different cases
and provide a simpler interface to the Python script. It also provides a number
of utilities that help in debugging scripts, and the latest addition is support
for file uploads from a form (if your browser supports it).
The output of a CGI script should consist of two sections, separated by a blank
line. The first section contains a number of headers, telling the client what
kind of data is following. Python code to generate a minimal header section
looks like this::
print "Content-Type: text/html" # HTML is following
print # blank line, end of headers
The second section is usually HTML, which allows the client software to display
nicely formatted text with header, in-line images, etc. Here's Python code that
prints a simple piece of HTML::
print "<TITLE>CGI script output</TITLE>"
print "<H1>This is my first CGI script</H1>"
print "Hello, world!"
.. _using-the-cgi-module:
Using the cgi module
--------------------
Begin by writing ``import cgi``. Do not use ``from cgi import *`` --- the
module defines all sorts of names for its own use or for backward compatibility
that you don't want in your namespace.
Merged revisions 68582,68718,68720-68721,68724-68727,68859,68973,69288-69289,69293,69295,69297-69301,69409,69414,69570,69573,69576,69728-69730,69769,69776,69803-69805,69840,69896 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r68582 | georg.brandl | 2009-01-13 23:14:01 +0100 (Di, 13 Jan 2009) | 2 lines Use assertRaises. ........ r68718 | georg.brandl | 2009-01-18 11:42:35 +0100 (So, 18 Jan 2009) | 1 line #4976: union() and intersection() take multiple args, but talk about "the other". ........ r68720 | georg.brandl | 2009-01-18 11:45:22 +0100 (So, 18 Jan 2009) | 1 line #4974: fix redundant mention of lists and tuples. ........ r68721 | georg.brandl | 2009-01-18 11:48:16 +0100 (So, 18 Jan 2009) | 1 line #4914: trunc is in math. ........ r68724 | georg.brandl | 2009-01-18 14:24:10 +0100 (So, 18 Jan 2009) | 1 line #4979: correct result range for some random functions. ........ r68725 | georg.brandl | 2009-01-18 14:47:26 +0100 (So, 18 Jan 2009) | 1 line #4857: fix augmented assignment target spec. ........ r68726 | georg.brandl | 2009-01-18 15:41:52 +0100 (So, 18 Jan 2009) | 1 line #4923: clarify what was added. ........ r68727 | georg.brandl | 2009-01-18 19:25:30 +0100 (So, 18 Jan 2009) | 1 line #4986: augassigns are not expressions. ........ r68859 | georg.brandl | 2009-01-22 19:29:28 +0100 (Do, 22 Jan 2009) | 2 lines Clarify wording. ........ r68973 | georg.brandl | 2009-01-26 22:29:38 +0100 (Mo, 26 Jan 2009) | 2 lines Copy over docs on advanced role features from Sphinx docs. ........ r69288 | georg.brandl | 2009-02-05 11:30:57 +0100 (Do, 05 Feb 2009) | 1 line #5153: fix typo in example. ........ r69289 | georg.brandl | 2009-02-05 11:37:07 +0100 (Do, 05 Feb 2009) | 1 line #5144: document that PySys_SetArgv prepends the script directory (or the empty string) to sys.path. ........ r69293 | georg.brandl | 2009-02-05 11:59:28 +0100 (Do, 05 Feb 2009) | 1 line #5059: fix example. ........ r69295 | georg.brandl | 2009-02-05 12:23:47 +0100 (Do, 05 Feb 2009) | 1 line PyErr_PrintEx is also in 2.x... ........ r69297 | georg.brandl | 2009-02-05 12:32:18 +0100 (Do, 05 Feb 2009) | 1 line #5015: document PythonHome API functions. ........ r69298 | georg.brandl | 2009-02-05 12:33:21 +0100 (Do, 05 Feb 2009) | 1 line #4827: fix callback example. ........ r69299 | georg.brandl | 2009-02-05 12:35:28 +0100 (Do, 05 Feb 2009) | 1 line #4820: use correct module for ctypes.util. ........ r69300 | georg.brandl | 2009-02-05 12:38:23 +0100 (Do, 05 Feb 2009) | 1 line #4563: disable alpha and roman lists, fixes wrong formatting of contributor list. ........ r69301 | georg.brandl | 2009-02-05 12:40:35 +0100 (Do, 05 Feb 2009) | 1 line #5031: fix Thread.daemon property docs. ........ r69409 | georg.brandl | 2009-02-07 13:21:17 +0100 (Sa, 07 Feb 2009) | 1 line #5174: fix wrong file closing in example. ........ r69414 | georg.brandl | 2009-02-07 19:49:54 +0100 (Sa, 07 Feb 2009) | 1 line make "super only for new-style classes" a note. ........ r69570 | georg.brandl | 2009-02-13 11:40:14 +0100 (Fr, 13 Feb 2009) | 1 line #4894: document "newurl" parameter to redirect_request(). ........ r69573 | georg.brandl | 2009-02-13 11:44:17 +0100 (Fr, 13 Feb 2009) | 1 line #3734: document complex coercing behavior better. ........ r69576 | georg.brandl | 2009-02-13 11:56:50 +0100 (Fr, 13 Feb 2009) | 1 line #1661108: note that urlsafe encoded string can contain "=". ........ r69728 | georg.brandl | 2009-02-18 01:22:55 +0100 (Mi, 18 Feb 2009) | 2 lines #5297: fix example. ........ r69729 | georg.brandl | 2009-02-18 01:25:13 +0100 (Mi, 18 Feb 2009) | 2 lines #5296: sequence -> iterable. ........ r69730 | georg.brandl | 2009-02-18 01:31:36 +0100 (Mi, 18 Feb 2009) | 2 lines #5268: mention VMSError. ........ r69769 | georg.brandl | 2009-02-19 09:30:06 +0100 (Do, 19 Feb 2009) | 1 line #5310, #3558: fix operator precedence table. ........ r69776 | georg.brandl | 2009-02-19 17:34:51 +0100 (Do, 19 Feb 2009) | 2 lines #5317: update IronPython URL. ........ r69803 | georg.brandl | 2009-02-20 08:48:21 +0100 (Fr, 20 Feb 2009) | 1 line #5327: fix a broken link by joining it. ........ r69804 | georg.brandl | 2009-02-20 09:22:21 +0100 (Fr, 20 Feb 2009) | 1 line At least separate imports from other statements. ........ r69805 | georg.brandl | 2009-02-20 09:45:47 +0100 (Fr, 20 Feb 2009) | 2 lines Fix punctuation. ........ r69840 | georg.brandl | 2009-02-21 20:09:40 +0100 (Sa, 21 Feb 2009) | 1 line #5338, #5339: two types in the API manual. ........ r69896 | georg.brandl | 2009-02-23 11:24:23 +0100 (Mo, 23 Feb 2009) | 1 line #5348: format() converts all kinds of values. ........
2009-02-23 06:41:11 -04:00
When you write a new script, consider adding these lines::
2007-08-15 11:28:01 -03:00
Merged revisions 68582,68718,68720-68721,68724-68727,68859,68973,69288-69289,69293,69295,69297-69301,69409,69414,69570,69573,69576,69728-69730,69769,69776,69803-69805,69840,69896 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r68582 | georg.brandl | 2009-01-13 23:14:01 +0100 (Di, 13 Jan 2009) | 2 lines Use assertRaises. ........ r68718 | georg.brandl | 2009-01-18 11:42:35 +0100 (So, 18 Jan 2009) | 1 line #4976: union() and intersection() take multiple args, but talk about "the other". ........ r68720 | georg.brandl | 2009-01-18 11:45:22 +0100 (So, 18 Jan 2009) | 1 line #4974: fix redundant mention of lists and tuples. ........ r68721 | georg.brandl | 2009-01-18 11:48:16 +0100 (So, 18 Jan 2009) | 1 line #4914: trunc is in math. ........ r68724 | georg.brandl | 2009-01-18 14:24:10 +0100 (So, 18 Jan 2009) | 1 line #4979: correct result range for some random functions. ........ r68725 | georg.brandl | 2009-01-18 14:47:26 +0100 (So, 18 Jan 2009) | 1 line #4857: fix augmented assignment target spec. ........ r68726 | georg.brandl | 2009-01-18 15:41:52 +0100 (So, 18 Jan 2009) | 1 line #4923: clarify what was added. ........ r68727 | georg.brandl | 2009-01-18 19:25:30 +0100 (So, 18 Jan 2009) | 1 line #4986: augassigns are not expressions. ........ r68859 | georg.brandl | 2009-01-22 19:29:28 +0100 (Do, 22 Jan 2009) | 2 lines Clarify wording. ........ r68973 | georg.brandl | 2009-01-26 22:29:38 +0100 (Mo, 26 Jan 2009) | 2 lines Copy over docs on advanced role features from Sphinx docs. ........ r69288 | georg.brandl | 2009-02-05 11:30:57 +0100 (Do, 05 Feb 2009) | 1 line #5153: fix typo in example. ........ r69289 | georg.brandl | 2009-02-05 11:37:07 +0100 (Do, 05 Feb 2009) | 1 line #5144: document that PySys_SetArgv prepends the script directory (or the empty string) to sys.path. ........ r69293 | georg.brandl | 2009-02-05 11:59:28 +0100 (Do, 05 Feb 2009) | 1 line #5059: fix example. ........ r69295 | georg.brandl | 2009-02-05 12:23:47 +0100 (Do, 05 Feb 2009) | 1 line PyErr_PrintEx is also in 2.x... ........ r69297 | georg.brandl | 2009-02-05 12:32:18 +0100 (Do, 05 Feb 2009) | 1 line #5015: document PythonHome API functions. ........ r69298 | georg.brandl | 2009-02-05 12:33:21 +0100 (Do, 05 Feb 2009) | 1 line #4827: fix callback example. ........ r69299 | georg.brandl | 2009-02-05 12:35:28 +0100 (Do, 05 Feb 2009) | 1 line #4820: use correct module for ctypes.util. ........ r69300 | georg.brandl | 2009-02-05 12:38:23 +0100 (Do, 05 Feb 2009) | 1 line #4563: disable alpha and roman lists, fixes wrong formatting of contributor list. ........ r69301 | georg.brandl | 2009-02-05 12:40:35 +0100 (Do, 05 Feb 2009) | 1 line #5031: fix Thread.daemon property docs. ........ r69409 | georg.brandl | 2009-02-07 13:21:17 +0100 (Sa, 07 Feb 2009) | 1 line #5174: fix wrong file closing in example. ........ r69414 | georg.brandl | 2009-02-07 19:49:54 +0100 (Sa, 07 Feb 2009) | 1 line make "super only for new-style classes" a note. ........ r69570 | georg.brandl | 2009-02-13 11:40:14 +0100 (Fr, 13 Feb 2009) | 1 line #4894: document "newurl" parameter to redirect_request(). ........ r69573 | georg.brandl | 2009-02-13 11:44:17 +0100 (Fr, 13 Feb 2009) | 1 line #3734: document complex coercing behavior better. ........ r69576 | georg.brandl | 2009-02-13 11:56:50 +0100 (Fr, 13 Feb 2009) | 1 line #1661108: note that urlsafe encoded string can contain "=". ........ r69728 | georg.brandl | 2009-02-18 01:22:55 +0100 (Mi, 18 Feb 2009) | 2 lines #5297: fix example. ........ r69729 | georg.brandl | 2009-02-18 01:25:13 +0100 (Mi, 18 Feb 2009) | 2 lines #5296: sequence -> iterable. ........ r69730 | georg.brandl | 2009-02-18 01:31:36 +0100 (Mi, 18 Feb 2009) | 2 lines #5268: mention VMSError. ........ r69769 | georg.brandl | 2009-02-19 09:30:06 +0100 (Do, 19 Feb 2009) | 1 line #5310, #3558: fix operator precedence table. ........ r69776 | georg.brandl | 2009-02-19 17:34:51 +0100 (Do, 19 Feb 2009) | 2 lines #5317: update IronPython URL. ........ r69803 | georg.brandl | 2009-02-20 08:48:21 +0100 (Fr, 20 Feb 2009) | 1 line #5327: fix a broken link by joining it. ........ r69804 | georg.brandl | 2009-02-20 09:22:21 +0100 (Fr, 20 Feb 2009) | 1 line At least separate imports from other statements. ........ r69805 | georg.brandl | 2009-02-20 09:45:47 +0100 (Fr, 20 Feb 2009) | 2 lines Fix punctuation. ........ r69840 | georg.brandl | 2009-02-21 20:09:40 +0100 (Sa, 21 Feb 2009) | 1 line #5338, #5339: two types in the API manual. ........ r69896 | georg.brandl | 2009-02-23 11:24:23 +0100 (Mo, 23 Feb 2009) | 1 line #5348: format() converts all kinds of values. ........
2009-02-23 06:41:11 -04:00
import cgitb
cgitb.enable()
2007-08-15 11:28:01 -03:00
This activates a special exception handler that will display detailed reports in
the Web browser if any errors occur. If you'd rather not show the guts of your
program to users of your script, you can have the reports saved to files
Merged revisions 68582,68718,68720-68721,68724-68727,68859,68973,69288-69289,69293,69295,69297-69301,69409,69414,69570,69573,69576,69728-69730,69769,69776,69803-69805,69840,69896 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r68582 | georg.brandl | 2009-01-13 23:14:01 +0100 (Di, 13 Jan 2009) | 2 lines Use assertRaises. ........ r68718 | georg.brandl | 2009-01-18 11:42:35 +0100 (So, 18 Jan 2009) | 1 line #4976: union() and intersection() take multiple args, but talk about "the other". ........ r68720 | georg.brandl | 2009-01-18 11:45:22 +0100 (So, 18 Jan 2009) | 1 line #4974: fix redundant mention of lists and tuples. ........ r68721 | georg.brandl | 2009-01-18 11:48:16 +0100 (So, 18 Jan 2009) | 1 line #4914: trunc is in math. ........ r68724 | georg.brandl | 2009-01-18 14:24:10 +0100 (So, 18 Jan 2009) | 1 line #4979: correct result range for some random functions. ........ r68725 | georg.brandl | 2009-01-18 14:47:26 +0100 (So, 18 Jan 2009) | 1 line #4857: fix augmented assignment target spec. ........ r68726 | georg.brandl | 2009-01-18 15:41:52 +0100 (So, 18 Jan 2009) | 1 line #4923: clarify what was added. ........ r68727 | georg.brandl | 2009-01-18 19:25:30 +0100 (So, 18 Jan 2009) | 1 line #4986: augassigns are not expressions. ........ r68859 | georg.brandl | 2009-01-22 19:29:28 +0100 (Do, 22 Jan 2009) | 2 lines Clarify wording. ........ r68973 | georg.brandl | 2009-01-26 22:29:38 +0100 (Mo, 26 Jan 2009) | 2 lines Copy over docs on advanced role features from Sphinx docs. ........ r69288 | georg.brandl | 2009-02-05 11:30:57 +0100 (Do, 05 Feb 2009) | 1 line #5153: fix typo in example. ........ r69289 | georg.brandl | 2009-02-05 11:37:07 +0100 (Do, 05 Feb 2009) | 1 line #5144: document that PySys_SetArgv prepends the script directory (or the empty string) to sys.path. ........ r69293 | georg.brandl | 2009-02-05 11:59:28 +0100 (Do, 05 Feb 2009) | 1 line #5059: fix example. ........ r69295 | georg.brandl | 2009-02-05 12:23:47 +0100 (Do, 05 Feb 2009) | 1 line PyErr_PrintEx is also in 2.x... ........ r69297 | georg.brandl | 2009-02-05 12:32:18 +0100 (Do, 05 Feb 2009) | 1 line #5015: document PythonHome API functions. ........ r69298 | georg.brandl | 2009-02-05 12:33:21 +0100 (Do, 05 Feb 2009) | 1 line #4827: fix callback example. ........ r69299 | georg.brandl | 2009-02-05 12:35:28 +0100 (Do, 05 Feb 2009) | 1 line #4820: use correct module for ctypes.util. ........ r69300 | georg.brandl | 2009-02-05 12:38:23 +0100 (Do, 05 Feb 2009) | 1 line #4563: disable alpha and roman lists, fixes wrong formatting of contributor list. ........ r69301 | georg.brandl | 2009-02-05 12:40:35 +0100 (Do, 05 Feb 2009) | 1 line #5031: fix Thread.daemon property docs. ........ r69409 | georg.brandl | 2009-02-07 13:21:17 +0100 (Sa, 07 Feb 2009) | 1 line #5174: fix wrong file closing in example. ........ r69414 | georg.brandl | 2009-02-07 19:49:54 +0100 (Sa, 07 Feb 2009) | 1 line make "super only for new-style classes" a note. ........ r69570 | georg.brandl | 2009-02-13 11:40:14 +0100 (Fr, 13 Feb 2009) | 1 line #4894: document "newurl" parameter to redirect_request(). ........ r69573 | georg.brandl | 2009-02-13 11:44:17 +0100 (Fr, 13 Feb 2009) | 1 line #3734: document complex coercing behavior better. ........ r69576 | georg.brandl | 2009-02-13 11:56:50 +0100 (Fr, 13 Feb 2009) | 1 line #1661108: note that urlsafe encoded string can contain "=". ........ r69728 | georg.brandl | 2009-02-18 01:22:55 +0100 (Mi, 18 Feb 2009) | 2 lines #5297: fix example. ........ r69729 | georg.brandl | 2009-02-18 01:25:13 +0100 (Mi, 18 Feb 2009) | 2 lines #5296: sequence -> iterable. ........ r69730 | georg.brandl | 2009-02-18 01:31:36 +0100 (Mi, 18 Feb 2009) | 2 lines #5268: mention VMSError. ........ r69769 | georg.brandl | 2009-02-19 09:30:06 +0100 (Do, 19 Feb 2009) | 1 line #5310, #3558: fix operator precedence table. ........ r69776 | georg.brandl | 2009-02-19 17:34:51 +0100 (Do, 19 Feb 2009) | 2 lines #5317: update IronPython URL. ........ r69803 | georg.brandl | 2009-02-20 08:48:21 +0100 (Fr, 20 Feb 2009) | 1 line #5327: fix a broken link by joining it. ........ r69804 | georg.brandl | 2009-02-20 09:22:21 +0100 (Fr, 20 Feb 2009) | 1 line At least separate imports from other statements. ........ r69805 | georg.brandl | 2009-02-20 09:45:47 +0100 (Fr, 20 Feb 2009) | 2 lines Fix punctuation. ........ r69840 | georg.brandl | 2009-02-21 20:09:40 +0100 (Sa, 21 Feb 2009) | 1 line #5338, #5339: two types in the API manual. ........ r69896 | georg.brandl | 2009-02-23 11:24:23 +0100 (Mo, 23 Feb 2009) | 1 line #5348: format() converts all kinds of values. ........
2009-02-23 06:41:11 -04:00
instead, with code like this::
2007-08-15 11:28:01 -03:00
Merged revisions 68582,68718,68720-68721,68724-68727,68859,68973,69288-69289,69293,69295,69297-69301,69409,69414,69570,69573,69576,69728-69730,69769,69776,69803-69805,69840,69896 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r68582 | georg.brandl | 2009-01-13 23:14:01 +0100 (Di, 13 Jan 2009) | 2 lines Use assertRaises. ........ r68718 | georg.brandl | 2009-01-18 11:42:35 +0100 (So, 18 Jan 2009) | 1 line #4976: union() and intersection() take multiple args, but talk about "the other". ........ r68720 | georg.brandl | 2009-01-18 11:45:22 +0100 (So, 18 Jan 2009) | 1 line #4974: fix redundant mention of lists and tuples. ........ r68721 | georg.brandl | 2009-01-18 11:48:16 +0100 (So, 18 Jan 2009) | 1 line #4914: trunc is in math. ........ r68724 | georg.brandl | 2009-01-18 14:24:10 +0100 (So, 18 Jan 2009) | 1 line #4979: correct result range for some random functions. ........ r68725 | georg.brandl | 2009-01-18 14:47:26 +0100 (So, 18 Jan 2009) | 1 line #4857: fix augmented assignment target spec. ........ r68726 | georg.brandl | 2009-01-18 15:41:52 +0100 (So, 18 Jan 2009) | 1 line #4923: clarify what was added. ........ r68727 | georg.brandl | 2009-01-18 19:25:30 +0100 (So, 18 Jan 2009) | 1 line #4986: augassigns are not expressions. ........ r68859 | georg.brandl | 2009-01-22 19:29:28 +0100 (Do, 22 Jan 2009) | 2 lines Clarify wording. ........ r68973 | georg.brandl | 2009-01-26 22:29:38 +0100 (Mo, 26 Jan 2009) | 2 lines Copy over docs on advanced role features from Sphinx docs. ........ r69288 | georg.brandl | 2009-02-05 11:30:57 +0100 (Do, 05 Feb 2009) | 1 line #5153: fix typo in example. ........ r69289 | georg.brandl | 2009-02-05 11:37:07 +0100 (Do, 05 Feb 2009) | 1 line #5144: document that PySys_SetArgv prepends the script directory (or the empty string) to sys.path. ........ r69293 | georg.brandl | 2009-02-05 11:59:28 +0100 (Do, 05 Feb 2009) | 1 line #5059: fix example. ........ r69295 | georg.brandl | 2009-02-05 12:23:47 +0100 (Do, 05 Feb 2009) | 1 line PyErr_PrintEx is also in 2.x... ........ r69297 | georg.brandl | 2009-02-05 12:32:18 +0100 (Do, 05 Feb 2009) | 1 line #5015: document PythonHome API functions. ........ r69298 | georg.brandl | 2009-02-05 12:33:21 +0100 (Do, 05 Feb 2009) | 1 line #4827: fix callback example. ........ r69299 | georg.brandl | 2009-02-05 12:35:28 +0100 (Do, 05 Feb 2009) | 1 line #4820: use correct module for ctypes.util. ........ r69300 | georg.brandl | 2009-02-05 12:38:23 +0100 (Do, 05 Feb 2009) | 1 line #4563: disable alpha and roman lists, fixes wrong formatting of contributor list. ........ r69301 | georg.brandl | 2009-02-05 12:40:35 +0100 (Do, 05 Feb 2009) | 1 line #5031: fix Thread.daemon property docs. ........ r69409 | georg.brandl | 2009-02-07 13:21:17 +0100 (Sa, 07 Feb 2009) | 1 line #5174: fix wrong file closing in example. ........ r69414 | georg.brandl | 2009-02-07 19:49:54 +0100 (Sa, 07 Feb 2009) | 1 line make "super only for new-style classes" a note. ........ r69570 | georg.brandl | 2009-02-13 11:40:14 +0100 (Fr, 13 Feb 2009) | 1 line #4894: document "newurl" parameter to redirect_request(). ........ r69573 | georg.brandl | 2009-02-13 11:44:17 +0100 (Fr, 13 Feb 2009) | 1 line #3734: document complex coercing behavior better. ........ r69576 | georg.brandl | 2009-02-13 11:56:50 +0100 (Fr, 13 Feb 2009) | 1 line #1661108: note that urlsafe encoded string can contain "=". ........ r69728 | georg.brandl | 2009-02-18 01:22:55 +0100 (Mi, 18 Feb 2009) | 2 lines #5297: fix example. ........ r69729 | georg.brandl | 2009-02-18 01:25:13 +0100 (Mi, 18 Feb 2009) | 2 lines #5296: sequence -> iterable. ........ r69730 | georg.brandl | 2009-02-18 01:31:36 +0100 (Mi, 18 Feb 2009) | 2 lines #5268: mention VMSError. ........ r69769 | georg.brandl | 2009-02-19 09:30:06 +0100 (Do, 19 Feb 2009) | 1 line #5310, #3558: fix operator precedence table. ........ r69776 | georg.brandl | 2009-02-19 17:34:51 +0100 (Do, 19 Feb 2009) | 2 lines #5317: update IronPython URL. ........ r69803 | georg.brandl | 2009-02-20 08:48:21 +0100 (Fr, 20 Feb 2009) | 1 line #5327: fix a broken link by joining it. ........ r69804 | georg.brandl | 2009-02-20 09:22:21 +0100 (Fr, 20 Feb 2009) | 1 line At least separate imports from other statements. ........ r69805 | georg.brandl | 2009-02-20 09:45:47 +0100 (Fr, 20 Feb 2009) | 2 lines Fix punctuation. ........ r69840 | georg.brandl | 2009-02-21 20:09:40 +0100 (Sa, 21 Feb 2009) | 1 line #5338, #5339: two types in the API manual. ........ r69896 | georg.brandl | 2009-02-23 11:24:23 +0100 (Mo, 23 Feb 2009) | 1 line #5348: format() converts all kinds of values. ........
2009-02-23 06:41:11 -04:00
import cgitb
cgitb.enable(display=0, logdir="/tmp")
2007-08-15 11:28:01 -03:00
It's very helpful to use this feature during script development. The reports
produced by :mod:`cgitb` provide information that can save you a lot of time in
tracking down bugs. You can always remove the ``cgitb`` line later when you
have tested your script and are confident that it works correctly.
To get at submitted form data, it's best to use the :class:`FieldStorage` class.
The other classes defined in this module are provided mostly for backward
compatibility. Instantiate it exactly once, without arguments. This reads the
form contents from standard input or the environment (depending on the value of
various environment variables set according to the CGI standard). Since it may
consume standard input, it should be instantiated only once.
Merged revisions 74008,74021-74022,74074-74075,74077,74148,74179,74188,74192-74194,74200,74205 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r74008 | benjamin.peterson | 2009-07-15 02:46:42 +0200 (Mi, 15 Jul 2009) | 1 line update year ........ r74021 | georg.brandl | 2009-07-16 09:33:04 +0200 (Do, 16 Jul 2009) | 1 line #6486: start with built in functions rather than "built in objects". ........ r74022 | georg.brandl | 2009-07-16 09:38:35 +0200 (Do, 16 Jul 2009) | 1 line #6481: fix typo in os.system() replacement. ........ r74074 | georg.brandl | 2009-07-18 11:03:10 +0200 (Sa, 18 Jul 2009) | 1 line #6513: fix example code: warning categories are classes, not instances. ........ r74075 | georg.brandl | 2009-07-18 11:06:31 +0200 (Sa, 18 Jul 2009) | 1 line #6505: fix typos. ........ r74077 | georg.brandl | 2009-07-18 11:43:40 +0200 (Sa, 18 Jul 2009) | 1 line #6489: fix an ambiguity in getiterator() documentation. ........ r74148 | ezio.melotti | 2009-07-21 22:18:27 +0200 (Di, 21 Jul 2009) | 1 line #6536 fixed typo ........ r74179 | ezio.melotti | 2009-07-22 23:08:49 +0200 (Mi, 22 Jul 2009) | 1 line #6423 has_key -> in ........ r74188 | benjamin.peterson | 2009-07-23 16:25:31 +0200 (Do, 23 Jul 2009) | 1 line use bools ........ r74192 | georg.brandl | 2009-07-24 18:28:38 +0200 (Fr, 24 Jul 2009) | 1 line Fix arg types of et#. ........ r74193 | georg.brandl | 2009-07-24 18:46:38 +0200 (Fr, 24 Jul 2009) | 1 line Dont put "void" in signature for nullary functions. ........ r74194 | georg.brandl | 2009-07-24 22:09:46 +0200 (Fr, 24 Jul 2009) | 1 line #6564: fix section about the two raise syntaxes. ........ r74200 | georg.brandl | 2009-07-25 15:02:15 +0200 (Sa, 25 Jul 2009) | 1 line #6571: add index entries for more operators. ........ r74205 | georg.brandl | 2009-07-26 15:36:39 +0200 (So, 26 Jul 2009) | 1 line #6576: fix cross-refs in re docs. ........
2009-10-27 11:34:21 -03:00
The :class:`FieldStorage` instance can be indexed like a Python dictionary.
It allows membership testing with the :keyword:`in` operator, and also supports
the standard dictionary method :meth:`keys` and the built-in function
:func:`len`. Form fields containing empty strings are ignored and do not appear
in the dictionary; to keep such values, provide a true value for the optional
*keep_blank_values* keyword parameter when creating the :class:`FieldStorage`
instance.
2007-08-15 11:28:01 -03:00
For instance, the following code (which assumes that the
:mailheader:`Content-Type` header and blank line have already been printed)
checks that the fields ``name`` and ``addr`` are both set to a non-empty
string::
form = cgi.FieldStorage()
Merged revisions 74008,74021-74022,74074-74075,74077,74148,74179,74188,74192-74194,74200,74205 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r74008 | benjamin.peterson | 2009-07-15 02:46:42 +0200 (Mi, 15 Jul 2009) | 1 line update year ........ r74021 | georg.brandl | 2009-07-16 09:33:04 +0200 (Do, 16 Jul 2009) | 1 line #6486: start with built in functions rather than "built in objects". ........ r74022 | georg.brandl | 2009-07-16 09:38:35 +0200 (Do, 16 Jul 2009) | 1 line #6481: fix typo in os.system() replacement. ........ r74074 | georg.brandl | 2009-07-18 11:03:10 +0200 (Sa, 18 Jul 2009) | 1 line #6513: fix example code: warning categories are classes, not instances. ........ r74075 | georg.brandl | 2009-07-18 11:06:31 +0200 (Sa, 18 Jul 2009) | 1 line #6505: fix typos. ........ r74077 | georg.brandl | 2009-07-18 11:43:40 +0200 (Sa, 18 Jul 2009) | 1 line #6489: fix an ambiguity in getiterator() documentation. ........ r74148 | ezio.melotti | 2009-07-21 22:18:27 +0200 (Di, 21 Jul 2009) | 1 line #6536 fixed typo ........ r74179 | ezio.melotti | 2009-07-22 23:08:49 +0200 (Mi, 22 Jul 2009) | 1 line #6423 has_key -> in ........ r74188 | benjamin.peterson | 2009-07-23 16:25:31 +0200 (Do, 23 Jul 2009) | 1 line use bools ........ r74192 | georg.brandl | 2009-07-24 18:28:38 +0200 (Fr, 24 Jul 2009) | 1 line Fix arg types of et#. ........ r74193 | georg.brandl | 2009-07-24 18:46:38 +0200 (Fr, 24 Jul 2009) | 1 line Dont put "void" in signature for nullary functions. ........ r74194 | georg.brandl | 2009-07-24 22:09:46 +0200 (Fr, 24 Jul 2009) | 1 line #6564: fix section about the two raise syntaxes. ........ r74200 | georg.brandl | 2009-07-25 15:02:15 +0200 (Sa, 25 Jul 2009) | 1 line #6571: add index entries for more operators. ........ r74205 | georg.brandl | 2009-07-26 15:36:39 +0200 (So, 26 Jul 2009) | 1 line #6576: fix cross-refs in re docs. ........
2009-10-27 11:34:21 -03:00
if "name" not in form or "addr" not in form:
2007-08-15 11:28:01 -03:00
print "<H1>Error</H1>"
print "Please fill in the name and addr fields."
return
print "<p>name:", form["name"].value
print "<p>addr:", form["addr"].value
...further form processing here...
Here the fields, accessed through ``form[key]``, are themselves instances of
:class:`FieldStorage` (or :class:`MiniFieldStorage`, depending on the form
encoding). The :attr:`value` attribute of the instance yields the string value
of the field. The :meth:`getvalue` method returns this string value directly;
it also accepts an optional second argument as a default to return if the
requested key is not present.
If the submitted form data contains more than one field with the same name, the
object retrieved by ``form[key]`` is not a :class:`FieldStorage` or
:class:`MiniFieldStorage` instance but a list of such instances. Similarly, in
this situation, ``form.getvalue(key)`` would return a list of strings. If you
expect this possibility (when your HTML form contains multiple fields with the
same name), use the :func:`getlist` function, which always returns a list of
values (so that you do not need to special-case the single item case). For
example, this code concatenates any number of username fields, separated by
commas::
value = form.getlist("username")
usernames = ",".join(value)
If a field represents an uploaded file, accessing the value via the
:attr:`value` attribute or the :func:`getvalue` method reads the entire file in
memory as a string. This may not be what you want. You can test for an uploaded
file by testing either the :attr:`filename` attribute or the :attr:`!file`
attribute. You can then read the data at leisure from the :attr:`!file`
2007-08-15 11:28:01 -03:00
attribute::
fileitem = form["userfile"]
if fileitem.file:
# It's an uploaded file; count lines
linecount = 0
while 1:
line = fileitem.file.readline()
if not line: break
linecount = linecount + 1
If an error is encountered when obtaining the contents of an uploaded file
(for example, when the user interrupts the form submission by clicking on
a Back or Cancel button) the :attr:`done` attribute of the object for the
field will be set to the value -1.
2007-08-15 11:28:01 -03:00
The file upload draft standard entertains the possibility of uploading multiple
files from one field (using a recursive :mimetype:`multipart/\*` encoding).
When this occurs, the item will be a dictionary-like :class:`FieldStorage` item.
This can be determined by testing its :attr:`!type` attribute, which should be
2007-08-15 11:28:01 -03:00
:mimetype:`multipart/form-data` (or perhaps another MIME type matching
:mimetype:`multipart/\*`). In this case, it can be iterated over recursively
just like the top-level form object.
When a form is submitted in the "old" format (as the query string or as a single
data part of type :mimetype:`application/x-www-form-urlencoded`), the items will
actually be instances of the class :class:`MiniFieldStorage`. In this case, the
:attr:`!list`, :attr:`!file`, and :attr:`filename` attributes are always ``None``.
2007-08-15 11:28:01 -03:00
A form submitted via POST that also has a query string will contain both
:class:`FieldStorage` and :class:`MiniFieldStorage` items.
2007-08-15 11:28:01 -03:00
Higher Level Interface
----------------------
.. versionadded:: 2.2
The previous section explains how to read CGI form data using the
:class:`FieldStorage` class. This section describes a higher level interface
which was added to this class to allow one to do it in a more readable and
intuitive way. The interface doesn't make the techniques described in previous
sections obsolete --- they are still useful to process file uploads efficiently,
for example.
2007-12-29 06:57:00 -04:00
.. XXX: Is this true ?
2007-08-15 11:28:01 -03:00
The interface consists of two simple methods. Using the methods you can process
form data in a generic way, without the need to worry whether only one or more
values were posted under one name.
In the previous section, you learned to write following code anytime you
expected a user to post more than one value under one name::
item = form.getvalue("item")
if isinstance(item, list):
# The user is requesting more than one item.
else:
# The user is requesting only one item.
This situation is common for example when a form contains a group of multiple
checkboxes with the same name::
<input type="checkbox" name="item" value="1" />
<input type="checkbox" name="item" value="2" />
In most situations, however, there's only one form control with a particular
name in a form and then you expect and need only one value associated with this
name. So you write a script containing for example this code::
user = form.getvalue("user").upper()
The problem with the code is that you should never expect that a client will
provide valid input to your scripts. For example, if a curious user appends
another ``user=foo`` pair to the query string, then the script would crash,
because in this situation the ``getvalue("user")`` method call returns a list
Merged revisions 74492,74531,74545-74550,74553-74555,74588,74603,74608,74614,74616-74618,74631-74633,74652-74653,74666,74671,74737,74739,74779,74781-74782,74784,74791,74793,74818-74820,74822,74832 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r74492 | r.david.murray | 2009-08-17 21:26:49 +0200 (Mo, 17 Aug 2009) | 2 lines Issue 6685: 'toupper' -> 'upper' in cgi doc example explanation. ........ r74531 | vinay.sajip | 2009-08-21 00:04:32 +0200 (Fr, 21 Aug 2009) | 1 line Added section on exceptions raised during logging. ........ r74545 | georg.brandl | 2009-08-24 19:14:29 +0200 (Mo, 24 Aug 2009) | 1 line #6772: mention utf-8 as utf8 alias. ........ r74546 | georg.brandl | 2009-08-24 19:20:40 +0200 (Mo, 24 Aug 2009) | 1 line #6725: spell "namespace" consistently. ........ r74547 | georg.brandl | 2009-08-24 19:22:05 +0200 (Mo, 24 Aug 2009) | 1 line #6718: fix example. ........ r74548 | georg.brandl | 2009-08-24 19:24:27 +0200 (Mo, 24 Aug 2009) | 1 line #6677: mention "deleting" as an alias for removing files. ........ r74549 | benjamin.peterson | 2009-08-24 19:42:36 +0200 (Mo, 24 Aug 2009) | 1 line fix pdf building by teaching latex the right encoding package ........ r74550 | georg.brandl | 2009-08-24 19:48:40 +0200 (Mo, 24 Aug 2009) | 1 line #6677: note that rmdir only removes empty directories. ........ r74553 | r.david.murray | 2009-08-27 03:04:59 +0200 (Do, 27 Aug 2009) | 2 lines Remove leftover text from end of sentence. ........ r74554 | georg.brandl | 2009-08-27 20:59:02 +0200 (Do, 27 Aug 2009) | 1 line Typo fix. ........ r74555 | georg.brandl | 2009-08-27 21:02:43 +0200 (Do, 27 Aug 2009) | 1 line #6787: reference fix. ........ r74588 | georg.brandl | 2009-08-30 10:35:01 +0200 (So, 30 Aug 2009) | 1 line #6803: fix old name. ........ r74603 | georg.brandl | 2009-08-31 08:38:29 +0200 (Mo, 31 Aug 2009) | 1 line other -> others where multiple arguments are accepted. ........ r74608 | senthil.kumaran | 2009-08-31 18:40:27 +0200 (Mo, 31 Aug 2009) | 3 lines Doc fix for the issue2637. ........ r74614 | georg.brandl | 2009-09-01 09:40:54 +0200 (Di, 01 Sep 2009) | 1 line #6813: better documentation for numberless string formats. ........ r74616 | georg.brandl | 2009-09-01 09:46:26 +0200 (Di, 01 Sep 2009) | 1 line #6808: clarification. ........ r74617 | georg.brandl | 2009-09-01 09:53:37 +0200 (Di, 01 Sep 2009) | 1 line #6765: hint that log(x, base) is not very sophisticated. ........ r74618 | georg.brandl | 2009-09-01 10:00:47 +0200 (Di, 01 Sep 2009) | 1 line #6810: add a link to the section about frame objects instead of just a description where to find it. ........ r74631 | georg.brandl | 2009-09-02 22:37:16 +0200 (Mi, 02 Sep 2009) | 1 line #6821: fix signature of PyBuffer_Release(). ........ r74632 | georg.brandl | 2009-09-03 09:27:26 +0200 (Do, 03 Sep 2009) | 1 line #6828: fix wrongly highlighted blocks. ........ r74633 | georg.brandl | 2009-09-03 14:31:39 +0200 (Do, 03 Sep 2009) | 1 line #6757: complete the list of types that marshal can serialize. ........ r74652 | georg.brandl | 2009-09-04 13:25:37 +0200 (Fr, 04 Sep 2009) | 1 line #6756: add some info about the "acct" parameter. ........ r74653 | georg.brandl | 2009-09-04 13:32:18 +0200 (Fr, 04 Sep 2009) | 1 line #6777: dont discourage usage of Exception.args or promote usage of Exception.message. ........ r74666 | georg.brandl | 2009-09-05 11:04:09 +0200 (Sa, 05 Sep 2009) | 1 line #6841: remove duplicated word. ........ r74671 | georg.brandl | 2009-09-05 18:47:17 +0200 (Sa, 05 Sep 2009) | 1 line #6843: add link from filterwarnings to where the meaning of the arguments is covered. ........ r74737 | georg.brandl | 2009-09-09 18:49:13 +0200 (Mi, 09 Sep 2009) | 1 line Properly document copy and deepcopy as functions. ........ r74739 | georg.brandl | 2009-09-11 09:55:20 +0200 (Fr, 11 Sep 2009) | 1 line Move function back to its section. ........ r74779 | michael.foord | 2009-09-13 18:13:36 +0200 (So, 13 Sep 2009) | 1 line Change to tutorial wording for reading text / binary files on Windows. Issue #6301. ........ r74781 | michael.foord | 2009-09-13 18:46:19 +0200 (So, 13 Sep 2009) | 1 line Note that sys._getframe is not guaranteed to exist in all implementations of Python, and a corresponding note in inspect.currentframe. Issue 6712. ........ r74782 | michael.foord | 2009-09-13 19:07:46 +0200 (So, 13 Sep 2009) | 1 line Tutorial tweaks. Issue 6849. ........ r74784 | georg.brandl | 2009-09-13 20:15:07 +0200 (So, 13 Sep 2009) | 1 line Typo fix. ........ r74791 | georg.brandl | 2009-09-14 16:08:54 +0200 (Mo, 14 Sep 2009) | 1 line #6574: list the future features in a table. ........ r74793 | georg.brandl | 2009-09-14 16:50:47 +0200 (Mo, 14 Sep 2009) | 1 line #6908: fix association of hashlib hash attributes. ........ r74818 | georg.brandl | 2009-09-16 11:23:04 +0200 (Mi, 16 Sep 2009) | 1 line #6880: add reference to classes section in exceptions section, which comes earlier. ........ r74819 | georg.brandl | 2009-09-16 11:24:57 +0200 (Mi, 16 Sep 2009) | 1 line #6876: fix base class constructor invocation in example. ........ r74820 | georg.brandl | 2009-09-16 11:30:48 +0200 (Mi, 16 Sep 2009) | 1 line #6891: comment out dead link to Unicode article. ........ r74822 | georg.brandl | 2009-09-16 12:12:06 +0200 (Mi, 16 Sep 2009) | 1 line #5621: refactor description of how class/instance attributes interact on a.x=a.x+1 or augassign. ........ r74832 | georg.brandl | 2009-09-16 17:57:46 +0200 (Mi, 16 Sep 2009) | 1 line Rewrap long lines. ........
2009-10-27 11:50:20 -03:00
instead of a string. Calling the :meth:`~str.upper` method on a list is not valid
2007-08-15 11:28:01 -03:00
(since lists do not have a method of this name) and results in an
:exc:`AttributeError` exception.
Therefore, the appropriate way to read form data values was to always use the
code which checks whether the obtained value is a single value or a list of
values. That's annoying and leads to less readable scripts.
A more convenient approach is to use the methods :meth:`getfirst` and
:meth:`getlist` provided by this higher level interface.
.. method:: FieldStorage.getfirst(name[, default])
This method always returns only one value associated with form field *name*.
The method returns only the first value in case that more values were posted
under such name. Please note that the order in which the values are received
may vary from browser to browser and should not be counted on. [#]_ If no such
form field or value exists then the method returns the value specified by the
optional parameter *default*. This parameter defaults to ``None`` if not
specified.
.. method:: FieldStorage.getlist(name)
This method always returns a list of values associated with form field *name*.
The method returns an empty list if no such form field or value exists for
*name*. It returns a list consisting of one item if only one such value exists.
Using these methods you can write nice compact code::
import cgi
form = cgi.FieldStorage()
user = form.getfirst("user", "").upper() # This way it's safe.
for item in form.getlist("item"):
do_something(item)
Old classes
-----------
.. deprecated:: 2.6
These classes, present in earlier versions of the :mod:`cgi` module, are
still supported for backward compatibility. New applications should use the
:class:`FieldStorage` class.
2007-08-15 11:28:01 -03:00
:class:`SvFormContentDict` stores single value form content as dictionary; it
assumes each field name occurs in the form only once.
:class:`FormContentDict` stores multiple value form content as a dictionary (the
form items are lists of values). Useful if your form contains multiple fields
with the same name.
Other classes (:class:`FormContent`, :class:`InterpFormContentDict`) are present
for backwards compatibility with really old applications only.
2007-08-15 11:28:01 -03:00
.. _functions-in-cgi-module:
Functions
---------
These are useful if you want more control, or if you want to employ some of the
algorithms implemented in this module in other circumstances.
.. function:: parse(fp[, keep_blank_values[, strict_parsing]])
Parse a query in the environment or from a file (the file defaults to
``sys.stdin``). The *keep_blank_values* and *strict_parsing* parameters are
passed to :func:`urlparse.parse_qs` unchanged.
2007-08-15 11:28:01 -03:00
.. function:: parse_qs(qs[, keep_blank_values[, strict_parsing]])
This function is deprecated in this module. Use :func:`urlparse.parse_qs`
instead. It is maintained here only for backward compatiblity.
2007-08-15 11:28:01 -03:00
.. function:: parse_qsl(qs[, keep_blank_values[, strict_parsing]])
This function is deprecated in this module. Use :func:`urlparse.parse_qsl`
instead. It is maintained here only for backward compatiblity.
2007-08-15 11:28:01 -03:00
.. function:: parse_multipart(fp, pdict)
Parse input of type :mimetype:`multipart/form-data` (for file uploads).
Arguments are *fp* for the input file and *pdict* for a dictionary containing
other parameters in the :mailheader:`Content-Type` header.
Returns a dictionary just like :func:`urlparse.parse_qs` keys are the field names, each
2007-08-15 11:28:01 -03:00
value is a list of values for that field. This is easy to use but not much good
if you are expecting megabytes to be uploaded --- in that case, use the
:class:`FieldStorage` class instead which is much more flexible.
Note that this does not parse nested multipart parts --- use
:class:`FieldStorage` for that.
.. function:: parse_header(string)
Parse a MIME header (such as :mailheader:`Content-Type`) into a main value and a
dictionary of parameters.
.. function:: test()
Robust test CGI script, usable as main program. Writes minimal HTTP headers and
formats all information provided to the script in HTML form.
.. function:: print_environ()
Format the shell environment in HTML.
.. function:: print_form(form)
Format a form in HTML.
.. function:: print_directory()
Format the current directory in HTML.
.. function:: print_environ_usage()
Print a list of useful (used by CGI) environment variables in HTML.
.. function:: escape(s[, quote])
Convert the characters ``'&'``, ``'<'`` and ``'>'`` in string *s* to HTML-safe
sequences. Use this if you need to display text that might contain such
characters in HTML. If the optional flag *quote* is true, the quotation mark
character (``'"'``) is also translated; this helps for inclusion in an HTML
attribute value, as in ``<A HREF="...">``. If the value to be quoted might
include single- or double-quote characters, or both, consider using the
:func:`quoteattr` function in the :mod:`xml.sax.saxutils` module instead.
.. _cgi-security:
Caring about security
---------------------
.. index:: pair: CGI; security
There's one important rule: if you invoke an external program (via the
:func:`os.system` or :func:`os.popen` functions. or others with similar
functionality), make very sure you don't pass arbitrary strings received from
the client to the shell. This is a well-known security hole whereby clever
hackers anywhere on the Web can exploit a gullible CGI script to invoke
arbitrary shell commands. Even parts of the URL or field names cannot be
trusted, since the request doesn't have to come from your form!
To be on the safe side, if you must pass a string gotten from a form to a shell
command, you should make sure the string contains only alphanumeric characters,
dashes, underscores, and periods.
Installing your CGI script on a Unix system
-------------------------------------------
Read the documentation for your HTTP server and check with your local system
administrator to find the directory where CGI scripts should be installed;
usually this is in a directory :file:`cgi-bin` in the server tree.
Make sure that your script is readable and executable by "others"; the Unix file
mode should be ``0755`` octal (use ``chmod 0755 filename``). Make sure that the
first line of the script contains ``#!`` starting in column 1 followed by the
pathname of the Python interpreter, for instance::
#!/usr/local/bin/python
Make sure the Python interpreter exists and is executable by "others".
Make sure that any files your script needs to read or write are readable or
writable, respectively, by "others" --- their mode should be ``0644`` for
readable and ``0666`` for writable. This is because, for security reasons, the
HTTP server executes your script as user "nobody", without any special
privileges. It can only read (write, execute) files that everybody can read
(write, execute). The current directory at execution time is also different (it
is usually the server's cgi-bin directory) and the set of environment variables
is also different from what you get when you log in. In particular, don't count
on the shell's search path for executables (:envvar:`PATH`) or the Python module
search path (:envvar:`PYTHONPATH`) to be set to anything interesting.
If you need to load modules from a directory which is not on Python's default
module search path, you can change the path in your script, before importing
other modules. For example::
import sys
sys.path.insert(0, "/usr/home/joe/lib/python")
sys.path.insert(0, "/usr/local/lib/python")
(This way, the directory inserted last will be searched first!)
Instructions for non-Unix systems will vary; check your HTTP server's
documentation (it will usually have a section on CGI scripts).
Testing your CGI script
-----------------------
Unfortunately, a CGI script will generally not run when you try it from the
command line, and a script that works perfectly from the command line may fail
mysteriously when run from the server. There's one reason why you should still
test your script from the command line: if it contains a syntax error, the
Python interpreter won't execute it at all, and the HTTP server will most likely
send a cryptic error to the client.
Assuming your script has no syntax errors, yet it does not work, you have no
choice but to read the next section.
Debugging CGI scripts
---------------------
.. index:: pair: CGI; debugging
First of all, check for trivial installation errors --- reading the section
above on installing your CGI script carefully can save you a lot of time. If
you wonder whether you have understood the installation procedure correctly, try
installing a copy of this module file (:file:`cgi.py`) as a CGI script. When
invoked as a script, the file will dump its environment and the contents of the
form in HTML form. Give it the right mode etc, and send it a request. If it's
installed in the standard :file:`cgi-bin` directory, it should be possible to
send it a request by entering a URL into your browser of the form::
http://yourhostname/cgi-bin/cgi.py?name=Joe+Blow&addr=At+Home
If this gives an error of type 404, the server cannot find the script -- perhaps
you need to install it in a different directory. If it gives another error,
there's an installation problem that you should fix before trying to go any
further. If you get a nicely formatted listing of the environment and form
content (in this example, the fields should be listed as "addr" with value "At
Home" and "name" with value "Joe Blow"), the :file:`cgi.py` script has been
installed correctly. If you follow the same procedure for your own script, you
should now be able to debug it.
The next step could be to call the :mod:`cgi` module's :func:`test` function
from your script: replace its main code with the single statement ::
cgi.test()
This should produce the same results as those gotten from installing the
:file:`cgi.py` file itself.
When an ordinary Python script raises an unhandled exception (for whatever
reason: of a typo in a module name, a file that can't be opened, etc.), the
Python interpreter prints a nice traceback and exits. While the Python
interpreter will still do this when your CGI script raises an exception, most
likely the traceback will end up in one of the HTTP server's log files, or be
discarded altogether.
Fortunately, once you have managed to get your script to execute *some* code,
you can easily send tracebacks to the Web browser using the :mod:`cgitb` module.
Merged revisions 68582,68718,68720-68721,68724-68727,68859,68973,69288-69289,69293,69295,69297-69301,69409,69414,69570,69573,69576,69728-69730,69769,69776,69803-69805,69840,69896 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r68582 | georg.brandl | 2009-01-13 23:14:01 +0100 (Di, 13 Jan 2009) | 2 lines Use assertRaises. ........ r68718 | georg.brandl | 2009-01-18 11:42:35 +0100 (So, 18 Jan 2009) | 1 line #4976: union() and intersection() take multiple args, but talk about "the other". ........ r68720 | georg.brandl | 2009-01-18 11:45:22 +0100 (So, 18 Jan 2009) | 1 line #4974: fix redundant mention of lists and tuples. ........ r68721 | georg.brandl | 2009-01-18 11:48:16 +0100 (So, 18 Jan 2009) | 1 line #4914: trunc is in math. ........ r68724 | georg.brandl | 2009-01-18 14:24:10 +0100 (So, 18 Jan 2009) | 1 line #4979: correct result range for some random functions. ........ r68725 | georg.brandl | 2009-01-18 14:47:26 +0100 (So, 18 Jan 2009) | 1 line #4857: fix augmented assignment target spec. ........ r68726 | georg.brandl | 2009-01-18 15:41:52 +0100 (So, 18 Jan 2009) | 1 line #4923: clarify what was added. ........ r68727 | georg.brandl | 2009-01-18 19:25:30 +0100 (So, 18 Jan 2009) | 1 line #4986: augassigns are not expressions. ........ r68859 | georg.brandl | 2009-01-22 19:29:28 +0100 (Do, 22 Jan 2009) | 2 lines Clarify wording. ........ r68973 | georg.brandl | 2009-01-26 22:29:38 +0100 (Mo, 26 Jan 2009) | 2 lines Copy over docs on advanced role features from Sphinx docs. ........ r69288 | georg.brandl | 2009-02-05 11:30:57 +0100 (Do, 05 Feb 2009) | 1 line #5153: fix typo in example. ........ r69289 | georg.brandl | 2009-02-05 11:37:07 +0100 (Do, 05 Feb 2009) | 1 line #5144: document that PySys_SetArgv prepends the script directory (or the empty string) to sys.path. ........ r69293 | georg.brandl | 2009-02-05 11:59:28 +0100 (Do, 05 Feb 2009) | 1 line #5059: fix example. ........ r69295 | georg.brandl | 2009-02-05 12:23:47 +0100 (Do, 05 Feb 2009) | 1 line PyErr_PrintEx is also in 2.x... ........ r69297 | georg.brandl | 2009-02-05 12:32:18 +0100 (Do, 05 Feb 2009) | 1 line #5015: document PythonHome API functions. ........ r69298 | georg.brandl | 2009-02-05 12:33:21 +0100 (Do, 05 Feb 2009) | 1 line #4827: fix callback example. ........ r69299 | georg.brandl | 2009-02-05 12:35:28 +0100 (Do, 05 Feb 2009) | 1 line #4820: use correct module for ctypes.util. ........ r69300 | georg.brandl | 2009-02-05 12:38:23 +0100 (Do, 05 Feb 2009) | 1 line #4563: disable alpha and roman lists, fixes wrong formatting of contributor list. ........ r69301 | georg.brandl | 2009-02-05 12:40:35 +0100 (Do, 05 Feb 2009) | 1 line #5031: fix Thread.daemon property docs. ........ r69409 | georg.brandl | 2009-02-07 13:21:17 +0100 (Sa, 07 Feb 2009) | 1 line #5174: fix wrong file closing in example. ........ r69414 | georg.brandl | 2009-02-07 19:49:54 +0100 (Sa, 07 Feb 2009) | 1 line make "super only for new-style classes" a note. ........ r69570 | georg.brandl | 2009-02-13 11:40:14 +0100 (Fr, 13 Feb 2009) | 1 line #4894: document "newurl" parameter to redirect_request(). ........ r69573 | georg.brandl | 2009-02-13 11:44:17 +0100 (Fr, 13 Feb 2009) | 1 line #3734: document complex coercing behavior better. ........ r69576 | georg.brandl | 2009-02-13 11:56:50 +0100 (Fr, 13 Feb 2009) | 1 line #1661108: note that urlsafe encoded string can contain "=". ........ r69728 | georg.brandl | 2009-02-18 01:22:55 +0100 (Mi, 18 Feb 2009) | 2 lines #5297: fix example. ........ r69729 | georg.brandl | 2009-02-18 01:25:13 +0100 (Mi, 18 Feb 2009) | 2 lines #5296: sequence -> iterable. ........ r69730 | georg.brandl | 2009-02-18 01:31:36 +0100 (Mi, 18 Feb 2009) | 2 lines #5268: mention VMSError. ........ r69769 | georg.brandl | 2009-02-19 09:30:06 +0100 (Do, 19 Feb 2009) | 1 line #5310, #3558: fix operator precedence table. ........ r69776 | georg.brandl | 2009-02-19 17:34:51 +0100 (Do, 19 Feb 2009) | 2 lines #5317: update IronPython URL. ........ r69803 | georg.brandl | 2009-02-20 08:48:21 +0100 (Fr, 20 Feb 2009) | 1 line #5327: fix a broken link by joining it. ........ r69804 | georg.brandl | 2009-02-20 09:22:21 +0100 (Fr, 20 Feb 2009) | 1 line At least separate imports from other statements. ........ r69805 | georg.brandl | 2009-02-20 09:45:47 +0100 (Fr, 20 Feb 2009) | 2 lines Fix punctuation. ........ r69840 | georg.brandl | 2009-02-21 20:09:40 +0100 (Sa, 21 Feb 2009) | 1 line #5338, #5339: two types in the API manual. ........ r69896 | georg.brandl | 2009-02-23 11:24:23 +0100 (Mo, 23 Feb 2009) | 1 line #5348: format() converts all kinds of values. ........
2009-02-23 06:41:11 -04:00
If you haven't done so already, just add the lines::
2007-08-15 11:28:01 -03:00
Merged revisions 68582,68718,68720-68721,68724-68727,68859,68973,69288-69289,69293,69295,69297-69301,69409,69414,69570,69573,69576,69728-69730,69769,69776,69803-69805,69840,69896 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r68582 | georg.brandl | 2009-01-13 23:14:01 +0100 (Di, 13 Jan 2009) | 2 lines Use assertRaises. ........ r68718 | georg.brandl | 2009-01-18 11:42:35 +0100 (So, 18 Jan 2009) | 1 line #4976: union() and intersection() take multiple args, but talk about "the other". ........ r68720 | georg.brandl | 2009-01-18 11:45:22 +0100 (So, 18 Jan 2009) | 1 line #4974: fix redundant mention of lists and tuples. ........ r68721 | georg.brandl | 2009-01-18 11:48:16 +0100 (So, 18 Jan 2009) | 1 line #4914: trunc is in math. ........ r68724 | georg.brandl | 2009-01-18 14:24:10 +0100 (So, 18 Jan 2009) | 1 line #4979: correct result range for some random functions. ........ r68725 | georg.brandl | 2009-01-18 14:47:26 +0100 (So, 18 Jan 2009) | 1 line #4857: fix augmented assignment target spec. ........ r68726 | georg.brandl | 2009-01-18 15:41:52 +0100 (So, 18 Jan 2009) | 1 line #4923: clarify what was added. ........ r68727 | georg.brandl | 2009-01-18 19:25:30 +0100 (So, 18 Jan 2009) | 1 line #4986: augassigns are not expressions. ........ r68859 | georg.brandl | 2009-01-22 19:29:28 +0100 (Do, 22 Jan 2009) | 2 lines Clarify wording. ........ r68973 | georg.brandl | 2009-01-26 22:29:38 +0100 (Mo, 26 Jan 2009) | 2 lines Copy over docs on advanced role features from Sphinx docs. ........ r69288 | georg.brandl | 2009-02-05 11:30:57 +0100 (Do, 05 Feb 2009) | 1 line #5153: fix typo in example. ........ r69289 | georg.brandl | 2009-02-05 11:37:07 +0100 (Do, 05 Feb 2009) | 1 line #5144: document that PySys_SetArgv prepends the script directory (or the empty string) to sys.path. ........ r69293 | georg.brandl | 2009-02-05 11:59:28 +0100 (Do, 05 Feb 2009) | 1 line #5059: fix example. ........ r69295 | georg.brandl | 2009-02-05 12:23:47 +0100 (Do, 05 Feb 2009) | 1 line PyErr_PrintEx is also in 2.x... ........ r69297 | georg.brandl | 2009-02-05 12:32:18 +0100 (Do, 05 Feb 2009) | 1 line #5015: document PythonHome API functions. ........ r69298 | georg.brandl | 2009-02-05 12:33:21 +0100 (Do, 05 Feb 2009) | 1 line #4827: fix callback example. ........ r69299 | georg.brandl | 2009-02-05 12:35:28 +0100 (Do, 05 Feb 2009) | 1 line #4820: use correct module for ctypes.util. ........ r69300 | georg.brandl | 2009-02-05 12:38:23 +0100 (Do, 05 Feb 2009) | 1 line #4563: disable alpha and roman lists, fixes wrong formatting of contributor list. ........ r69301 | georg.brandl | 2009-02-05 12:40:35 +0100 (Do, 05 Feb 2009) | 1 line #5031: fix Thread.daemon property docs. ........ r69409 | georg.brandl | 2009-02-07 13:21:17 +0100 (Sa, 07 Feb 2009) | 1 line #5174: fix wrong file closing in example. ........ r69414 | georg.brandl | 2009-02-07 19:49:54 +0100 (Sa, 07 Feb 2009) | 1 line make "super only for new-style classes" a note. ........ r69570 | georg.brandl | 2009-02-13 11:40:14 +0100 (Fr, 13 Feb 2009) | 1 line #4894: document "newurl" parameter to redirect_request(). ........ r69573 | georg.brandl | 2009-02-13 11:44:17 +0100 (Fr, 13 Feb 2009) | 1 line #3734: document complex coercing behavior better. ........ r69576 | georg.brandl | 2009-02-13 11:56:50 +0100 (Fr, 13 Feb 2009) | 1 line #1661108: note that urlsafe encoded string can contain "=". ........ r69728 | georg.brandl | 2009-02-18 01:22:55 +0100 (Mi, 18 Feb 2009) | 2 lines #5297: fix example. ........ r69729 | georg.brandl | 2009-02-18 01:25:13 +0100 (Mi, 18 Feb 2009) | 2 lines #5296: sequence -> iterable. ........ r69730 | georg.brandl | 2009-02-18 01:31:36 +0100 (Mi, 18 Feb 2009) | 2 lines #5268: mention VMSError. ........ r69769 | georg.brandl | 2009-02-19 09:30:06 +0100 (Do, 19 Feb 2009) | 1 line #5310, #3558: fix operator precedence table. ........ r69776 | georg.brandl | 2009-02-19 17:34:51 +0100 (Do, 19 Feb 2009) | 2 lines #5317: update IronPython URL. ........ r69803 | georg.brandl | 2009-02-20 08:48:21 +0100 (Fr, 20 Feb 2009) | 1 line #5327: fix a broken link by joining it. ........ r69804 | georg.brandl | 2009-02-20 09:22:21 +0100 (Fr, 20 Feb 2009) | 1 line At least separate imports from other statements. ........ r69805 | georg.brandl | 2009-02-20 09:45:47 +0100 (Fr, 20 Feb 2009) | 2 lines Fix punctuation. ........ r69840 | georg.brandl | 2009-02-21 20:09:40 +0100 (Sa, 21 Feb 2009) | 1 line #5338, #5339: two types in the API manual. ........ r69896 | georg.brandl | 2009-02-23 11:24:23 +0100 (Mo, 23 Feb 2009) | 1 line #5348: format() converts all kinds of values. ........
2009-02-23 06:41:11 -04:00
import cgitb
cgitb.enable()
2007-08-15 11:28:01 -03:00
to the top of your script. Then try running it again; when a problem occurs,
you should see a detailed report that will likely make apparent the cause of the
crash.
If you suspect that there may be a problem in importing the :mod:`cgitb` module,
you can use an even more robust approach (which only uses built-in modules)::
import sys
sys.stderr = sys.stdout
print "Content-Type: text/plain"
print
...your code here...
This relies on the Python interpreter to print the traceback. The content type
of the output is set to plain text, which disables all HTML processing. If your
script works, the raw HTML will be displayed by your client. If it raises an
exception, most likely after the first two lines have been printed, a traceback
will be displayed. Because no HTML interpretation is going on, the traceback
will be readable.
Common problems and solutions
-----------------------------
* Most HTTP servers buffer the output from CGI scripts until the script is
completed. This means that it is not possible to display a progress report on
the client's display while the script is running.
* Check the installation instructions above.
* Check the HTTP server's log files. (``tail -f logfile`` in a separate window
may be useful!)
* Always check a script for syntax errors first, by doing something like
``python script.py``.
* If your script does not have any syntax errors, try adding ``import cgitb;
cgitb.enable()`` to the top of the script.
* When invoking external programs, make sure they can be found. Usually, this
means using absolute path names --- :envvar:`PATH` is usually not set to a very
useful value in a CGI script.
* When reading or writing external files, make sure they can be read or written
by the userid under which your CGI script will be running: this is typically the
userid under which the web server is running, or some explicitly specified
userid for a web server's ``suexec`` feature.
* Don't try to give a CGI script a set-uid mode. This doesn't work on most
systems, and is a security liability as well.
.. rubric:: Footnotes
.. [#] Note that some recent versions of the HTML specification do state what order the
field values should be supplied in, but knowing whether a request was
received from a conforming browser, or even from a browser at all, is tedious
and error-prone.