Ruby Basics
Ruby Advanced
Ruby Useful Resources
Selected Reading
- Ruby - Exceptions
- Ruby - File I/O
- Ruby - Iterators
- Ruby - Ranges
- Ruby - Date & Time
- Ruby - Hashes
- Ruby - Arrays
- Ruby - Strings
- Ruby - Modules
- Ruby - Blocks
- Ruby - Methods
- Ruby - Loops
- Ruby - IF...ELSE
- Ruby - Comments
- Ruby - Operators
- Ruby - Variables
- Ruby - Classes and Objects
- Ruby - Syntax
- Ruby - Environment Setup
- Ruby - Overview
- Ruby - Home
Ruby Advanced
- Ruby - Associated Tools
- Ruby - Predefined Constants
- Ruby - Predefined Variables
- Ruby - Built-in Functions
- Ruby - Multithreading
- Ruby - Ruby/LDAP Tutorial
- Ruby - Tk Guide
- Ruby - Web Services
- Ruby - Ruby/XML, XSLT
- Ruby - Socket Programming
- Ruby - Sending Email
- Ruby - Web Applications
- Ruby - Database Access
- Ruby - Regular Expressions
- Ruby - Object Oriented
Ruby Useful Resources
Selected Reading
- Who is Who
- Computer Glossary
- HR Interview Questions
- Effective Resume Writing
- Questions and Answers
- UPSC IAS Exams Notes
Ruby - Web Applications
Ruby Web Apppcations - CGI Programming
Ruby is a general-purpose language; it can t properly be called a web language at all. Even so, web apppcations and web tools in general are among the most common uses of Ruby.
Not only can you write your own SMTP server, FTP daemon, or Web server in Ruby, but you can also use Ruby for more usual tasks such as CGI programming or as a replacement for PHP.
Please spend few minutes with Tutorial for more detail on CGI Programming.
Writing CGI Scripts
The most basic Ruby CGI script looks pke this −
#!/usr/bin/ruby puts "HTTP/1.0 200 OK" puts "Content-type: text/html " puts "<html><body>This is a test</body></html>"
If you call this script test.cgi and uploaded it to a Unix-based Web hosting provider with the right permissions, you could use it as a CGI script.
For example, if you have the Web site hosted with a Linux Web hosting provider and you upload test.cgi to the main directory and give it execute permissions, then visiting should return an HTML page saying This is a test.
Here when test.cgi is requested from a Web browser, the Web server looks for test.cgi on the Web site, and then executes it using the Ruby interpreter. The Ruby script returns a basic HTTP header and then returns a basic HTML document.
Using cgi.rb
Ruby comes with a special pbrary called cgi that enables more sophisticated interactions than those with the preceding CGI script.
Let s create a basic CGI script that uses cgi −
#!/usr/bin/ruby require cgi cgi = CGI.new puts cgi.header puts "<html><body>This is a test</body></html>"
Here, you created a CGI object and used it to print the header pne for you.
Form Processing
Using class CGI gives you access to HTML query parameters in two ways. Suppose we are given a URL of /cgi-bin/test.cgi?FirstName = Zara&LastName = Ap.
You can access the parameters FirstName and LastName using CGI#[] directly as follows −
#!/usr/bin/ruby require cgi cgi = CGI.new cgi[ FirstName ] # => ["Zara"] cgi[ LastName ] # => ["Ap"]
There is another way to access these form variables. This code will give you a hash of all the key and values −
#!/usr/bin/ruby
require cgi
cgi = CGI.new
h = cgi.params # => {"FirstName"=>["Zara"],"LastName"=>["Ap"]}
h[ FirstName ] # => ["Zara"]
h[ LastName ] # => ["Ap"]
Following is the code to retrieve all the keys −
#!/usr/bin/ruby require cgi cgi = CGI.new cgi.keys # => ["FirstName", "LastName"]
If a form contains multiple fields with the same name, the corresponding values will be returned to the script as an array. The [] accessor returns just the first of these.index the result of the params method to get them all.
In this example, assume the form has three fields called "name" and we entered three names "Zara", "Huma" and "Nuha" −
#!/usr/bin/ruby
require cgi
cgi = CGI.new
cgi[ name ] # => "Zara"
cgi.params[ name ] # => ["Zara", "Huma", "Nuha"]
cgi.keys # => ["name"]
cgi.params # => {"name"=>["Zara", "Huma", "Nuha"]}
Note − Ruby will take care of GET and POST methods automatically. There is no separate treatment for these two different methods.
An associated, but basic, form that could send the correct data would have the HTML code pke so −
<html>
<body>
<form method = "POST" action = "http://www.example.com/test.cgi">
First Name :<input type = "text" name = "FirstName" value = "" />
<br />
Last Name :<input type = "text" name = "LastName" value = "" />
<input type = "submit" value = "Submit Data" />
</form>
</body>
</html>
Creating Forms and HTML
CGI contains a huge number of methods used to create HTML. You will find one method per tag. In order to enable these methods, you must create a CGI object by calpng CGI.new.
To make tag nesting easier, these methods take their content as code blocks. The code blocks should return a String, which will be used as the content for the tag. For example −
#!/usr/bin/ruby
require "cgi"
cgi = CGI.new("html4")
cgi.out {
cgi.html {
cgi.head { "
"+cgi.title{"This Is a Test"} } +
cgi.body { "
"+
cgi.form {"
"+
cgi.hr +
cgi.h1 { "A Form: " } + "
"+
cgi.textarea("get_text") +"
"+
cgi.br +
cgi.submit
}
}
}
}
NOTE − The form method of the CGI class can accept a method parameter, which will set the HTTP method ( GET, POST, and so on...) to be used on form submittal. The default, used in this example, is POST.
This will produce the following result −
Content-Type: text/html
Content-Length: 302
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Final//EN">
<HTML>
<HEAD>
<TITLE>This Is a Test</TITLE>
</HEAD>
<BODY>
<FORM METHOD = "post" ENCTYPE = "apppcation/x-www-form-urlencoded">
<HR>
<H1>A Form: </H1>
<TEXTAREA COLS = "70" NAME = "get_text" ROWS = "10"></TEXTAREA>
<BR>
<INPUT TYPE = "submit">
</FORM>
</BODY>
</HTML>
Quoting Strings
When deapng with URLs and HTML code, you must be careful to quote certain characters. For instance, a slash character ( / ) has special meaning in a URL, so it must be escaped if it s not part of the pathname.
For example, any / in the query portion of the URL will be translated to the string %2F and must be translated back to a / for you to use it. Space and ampersand are also special characters. To handle this, CGI provides the routines CGI.escape and CGI.unescape.
#!/usr/bin/ruby require cgi puts CGI.escape(Zara Ap/A Sweet & Sour Girl")
This will produce the following result −
Zara+Ap%2FA Sweet+%26+Sour+Girl")
#!/usr/bin/ruby require cgi puts CGI.escapeHTML( <h1>Zara Ap/A Sweet & Sour Girl</h1> )
This will produce the following result −
<h1>Zara Ap/A Sweet & Sour Girl</h1>
Useful Methods in CGI Class
Here is the pst of methods related to CGI class −
The − Methods related to Standard CGI pbrary.
Cookies and Sessions
We have explained these two concepts in different sections. Please follow the sections −
The − How to handle CGI Cookies.
The − How to manage CGI sessions.
Web Hosting Servers
You could check the following topic on the internet to host your website on a Unix-based Server −