4.5 Form Processing

The data from the user can be information about the user, information about something wanted, or purchase information. The possibilities are endless.

There are two primary ways for the CGI program to get the data, "POST" & "GET". POST sends the input through the the standard input to the CGI program while GET uses the environment variable "QUERY_STRING". You can determine the type of request by looking at the environment variable "REQUEST_METHOD".

The details in handling the the character translations and different form methods needs little attention. Use someone else's code to do it. Look at the file common.pl for some ideas, or just use it. You may want to revise your last lab so that it can handle forms using ether method.

4.5.1 Preparation

1. Read Chapter 4 of CGI Programming by Gundavaram On the web at O'Reilly. Pages 51-85.
2. Create a form, and point it at your environment program. Look at the environment created by the HTTPD as provided to your program when presented with a form.
3. If you choose, modify the program to look at the standard input STDIN if the request method is "POST".

4.5.2 Group Task

• Construct an HTML form that has the following fields:
  1. Date (Month, Day, Year)
  2. Time (24 Hour time or 12 Hour and "AM" & "PM")
  3. Temperature (I think in Fahrenheit)
  4. Event "Radio Buttons" for the type of weather.
     • Clear
     • Tornadoes
     • Cloudy
     • Rain
     • Hail
     • Sleet
     • Snow
     • Fog
     • Oobleck See: Bartholomew and the Oobleck
• Write a CGI Perl program that:
  1. Creates a data file if it doesn't exist.
  2. Saves the data from the form to the file. Use the name of your script without the .pl with an .data. If the file already has data in it, append the new data to the file. Time stamp the entries in the file.
  3. Deals with race conditions by locking the file on write.
  4. Processes the data in name.data and displays the data in a table.
  5. Compute the average of the temperature fields. Include this information on your page.
  6. Count the occurrence of each event and display this information in a second table.
  7. Incorporates the data entry form, so the user can add additional data. (So you won't need a separate form when you are done, you might need it to get it to work initially.)
  8. IF the "GD" module is installed, create a histogram of the temperature between 0 and 100 (throw out the other data) and plot a red line showing the average.

4.5.3 Report

• Louis Taber
• CSC266 Topic: 4.5: Form processing.
• Your group letter.
• Your group member's names.

1. A printout of your Perl CGI program.
2. A printout of your file (not too much data, just enough to show your format.
3. A printout of your processed data report from a web browser.