CGI Programming with Perl

CGI Programming with `Perl`

The `CGI.pm` Format

The most common task of a CGI program is to create the required HTML tags.

Forms, buttons, lists

A standard set of routines has been created

CGI.pm is a Perl module of functions for such common tasks

CGI.pm is part of the standard Perl distribution

perldoc CGI

The use declaration in Perl specifies that it needs access to a particular module
```
use CGI ":standard";
```

Common CGI.pm functions

Perl shortcuts functions produce tags with the same name by using parameters passed to them for attributes and content.

A shortcut function may take several different kinds of parameters
- No parameters
```
br; # produces <br />
```
- A scalar variable or literal
```
h1("this is my header");  # produces <h1>this is my header</h1>
```
- A reference to an array or list
- A reference to a hash
Tags can have both content and attributes
- Each attribute tag is passed in a name/vale pair form used in a hash literal
  - The name of the attribute preceded by a "-", is the key
  - The proposed value is the target of the =>
```
textarea( -name => "Description",
          -rows => "2",
          -cols => "35"
);
```
  Produces:
```
<textarea name = "Description" rows =2 cols =35> </textarea>
```
  Note the unquoted numeric literal which do not conform with XHTML yet!!!
- If both attributes and content are passed:
  - Attributes must be the first parameter
  - Attributes are specified by a has literal
```
a({-href => "bread.html"}, "Press here for Artizan bread choices");
```
  Produces
```
Press here for Artizan bread choices
```
- The tags and their attributes are distributed over parameters to the function
```
ol(li({-type ++ "square"}, ["milk", "bread", "cheese"]));
```
  Produces
```
<ol>
   <li type ="square">milk</li>
   <li type ="square">bread</li>
   <li type ="square">cheese</li>
</ol>
```
  The collection can be specified just once, and the values can be specified as a reference to an array
```
radio_group( -name => 'colors'
             -value => ['blue', 'green', 'yellow', 'red'],
             -default => 'blue');
```
  Produces:
```
<input type="radio" name="colors" value="blue" checked /> blue
<input type="radio" name="colors" value="green" /> green
<input type="radio" name="colors" value="yellow" /> yellow
<input type="radio" name="colors" value="red" /> red
```

Boilerplate CGI.pm functions are not shortcuts

header();

Produces

Content-type: text/html;charset-ISO-8859-1
-- blnk line --

start_html("The college Wild Web Documents");

Produces

<!DOCTYPE html
	PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.we.org/1999/xhtml" lang="en-US">
<head><title> The college Wild Web Documents </title></head>
<body>

```
end_html();
```
Produces:
```
</body></html>
```

Query-strings:
```
name=Chuz%20Ramirez&payment=MasterCard
```
A form-processing program must
- Extract the form data from the query string
- Decode the query string and set local variables to the values can be achieved with the param function
```
param("name"); #produces "Chuz Ramirez"
```
- For the whole query string:
```
my($name, $payment) = (param("name), param("payment"));
```

<!DOCTYPE html PUBLIC "-//w3c//DTD XHTML 1.0 Strict//EN"
  "http://www.w3.org/TR/xhtml1/DTD/xhtml-strict.dtd">

<!-- popcorn.html - This describes popcorn sales form page -->
<html>
<head>
<title> Popcorn Sales CGI program </title>
</head>
<body>

<!-- The next line gives the address of the CGI program -->

<form action = "http://personal.utulsa.edu/~diaz/cgi-bin/popcorn.pl" 
      method = "POST">
<h2> Welcome to Millennium Gymnastics Booster Club Popcorn Sales </h2>

<table>

<!-- Text widgets for name and address -->

    <tr>
        <td> Buyer's Name: </td>  
        <td> <input type = "text"  name = "name"  size = "30"> </td>
    </tr>
    <tr>
        <td> Street Address: </td>
        <td> <input type = "text"  name = "street"  size = "30"> </td>
    </tr>
    <tr>
        <td> City, State, Zip: </td>
        <td> <input type = "text"  name = "city"  size = "30"> </td>
    </tr>
</table>
<br />

<table border = "border">

<!-- First, the column headings --> 

    <tr>
        <th> Product Name </th>
        <th> Price </th>
        <th> Quantity </th>
    </tr>

<!-- Now, the table data entries -->

    <tr>
        <td> Unpopped Popcorn (1 lb.) </td>
        <td> $3.00 </td>
        <td> <input type = "text"  name = "unpop"  size ="2"> </td>
    </tr>
    <tr>
        <td> Caramel Popcorn (2 lb. canister) </td>
        <td> $3.50 </td>
        <td> <input type = "text"  name = "caramel"  
              size = "2"> </td>
    </tr> 
    <tr>
        <td> Caramel Nut Popcorn (2 lb. canister) </td>
        <td> $4.50 </td>
        <td> <input type = "text"  name = "caramelnut"  
              size = "2"></td>
    </tr>
    </tr>
        <td> Toffey Nut Popcorn (2 lb. canister) </td>
        <td> $5.00 <</td>
        <td> <input type = "text"  name = "toffeynut"  
                      size = "2"> </td>
    </tr> 

</table>
<br />

<!-- The radio buttons for the payment method -->

<h3> Payment Method: </h3>
<input type = "radio"  name = "payment"  value = "visa" checked> Visa <br />

<input type = "radio"  name = "payment"  value = "mc"> Master Card <br />
<input type = "radio"  name = "payment"  value = "discover"> Discover <br />

<input type = "radio"  name = "payment"  value = "check"> Check <br /> <br />


<!-- The submit and reset buttons -->

<input type = "submit"  value = "Submit Order">
<input type = "reset"  value = "Clear Order Form">

</form>
</body>
</html>

popcorn HTML form

#!/usr/local/bin/perl -w

# This is popcorn.pl
# It is a CGI program to process the popcorn sales form

# Initialize a hash of products and their prices, total price,
#  and total number of purchased items

%prices = ("unpop" => 3, "caramel" => 3.5, "caramelnut" => 4.5,
           "toffeynut" => 5);
$total_price = 0;
$total_items = 0;

# Produce the header part of the HTML return value

print "Content-type: text/html\n\n";
print "<html><head>\n";
print "<title> CGI-Perl Popcorn Form  </title></head> \n";
print "<body>\n";
print "Thank you for your order. <br /> <br />\n";

# Determine the request method and get the query string

$request_method = $ENV{'REQUEST_METHOD'};
if ($request_method eq "GET") {
    $query_string = $ENV{'QUERY_STRING'};
}
elsif ($request_method eq "POST") {
    read(STDIN, $query_string, $ENV{'CONTENT_LENGTH'});
}

# Split the query string into the name/value pairs

@name_value_pairs = split(/&/, $query_string);

# Loop to process the array of item names and quantities

foreach $name_value (@name_value_pairs) {

# Split the pairs into names and values and translate the values
# into text by decoding the hex characters

    ($name, $value) = split (/=/, $name_value);
    $value =~ s/%([\dA-Fa-f][\dA-Fa-f])/pack("C", hex($1))/eg;

# Add the number of these items to the total items ordered, 
#  compute the cost of the item, and add its cost to the total price, 

    $total_items += $value;
    $cost = $prices{$name} * $value;
    $total_price += $cost;

} ##- end of foreach

# Produce the result information to the browser and finish the page

print "You ordered $total_items popcorn items <br /> <br /> \n";
print "Your total bill is: \$ $total_price <br /> \n";
print "</body> </html> \n";

CGI Programming with Perl

The CGI.pm Format

CGI Programming with `Perl`

The `CGI.pm` Format