Credit: Richie Hindle
You want to lead a simpler life
when writing simple CGI scripts, accessing form fields from a simple
dictionary rather than from a cgi.FieldStorage
instance.
The cgi
module offers sophisticated functionality
in its
FieldStorage
class, but for most web pages, you can
access the form’s data as a normal dictionary.
It’s not hard to build the dictionary from the
FieldStorage
object:
#!/usr/bin/python import cgi def cgiFieldStorageToDict(fieldStorage): """ Get a plain dictionary rather than the '.value' system used by the cgi module's native fieldStorage class. """ params = {} for key in fieldStorage.keys( ): params[key] = fieldStorage[key].value return params if _ _name_ _ == "_ _main_ _": dict = cgiFieldStorageToDict(cgi.FieldStorage( )) print "Content-Type: text/plain" print print dict
Rather than using Python’s
cgi.FieldStorage
class, a simple dictionary is
enough for 90% of CGI scripts. This recipe shows you how to convert a
FieldStorage
object into a simple dictionary.
Install the above script into your cgi-bin
directory as
cgitest.py
,
then visit the script with some parameters. For example:
http://your-server/cgi-bin/cgitest.py?x=y
You should see a simple dictionary printed in response:
{'x': 'y'}
Note that the first line of the script must give the complete path to the Python interpreter with which you want to run your CGI script, so you may have to edit it, depending on your configuration and setup.
The FieldStorage
system is necessary when your
HTML form contains multiple fields with the same name, or when users
upload large files to your script, but if all you have is a simple
set of uniquely named controls, a plain dictionary is easier (and
more Pythonic!) to work with. Since the point of the recipe is
simplicity, we of course do not want to do anything complicated, such
as subclassing FieldStorage
or anything similar;
getting a simple dictionary is the whole point, and this recipe is a
simple way to satisfy this simple requirement.
Recipe 11.2 for a quick way to test your CGI
setup; documentation of the standard library module
cgi
in the Library Reference;
a basic introduction to the CGI protocol is available at http://hoohoo.ncsa.uiuc.edu/cgi/overview.html.