Writing Apache Modules with Perl and C

4.4. Processing Input

You can make the virtual documents generated by the Apache API interactive in exactly the way that you would documents generated by CGI scripts. Your module will generate an HTML form for the user to fill out. When the user completes and submits the form, your module will process the parameters and generate a new document, which may contain another fill-out form that prompts the user for additional information. In addition, you can store information inside the URI itself by placing it in the additional path information part.

4.4.1. CGI Parameters

When a fill-out form is submitted, the contents of its fields are turned into a series of name=value parameter pairs that are available for your module's use. Unfortunately, correctly processing these parameter pairs is annoying because, for a number of historical reasons, there are a variety of formats that you must know about and deal with. The first complication is that the form may be submitted using either the HTTP GET or POST method. If the GET method is used, the URI encoded parameter pairs can be found separated by ampersands in the "query string," the part of the URI that follows the ? character:

http://your.site/uri/path?name1=val1&name2=val2&name3=val3...

To recover the parameters from a GET request, mod_perl users should use the request object's args( ) method. In a scalar context this method returns the entire query string, ampersands and all. In an array context, this method returns the parsed ...