CGI (Common Gateway Interface) programming in Ruby allows developers to create dynamic web applications. It provides a standard way for web servers to interact with external programs, enabling the generation of dynamic content.
CGI is a protocol that defines how web servers communicate with external programs. In Ruby, the CGI library facilitates the creation of CGI scripts, handling form data, and generating HTML responses.
To begin CGI programming in Ruby, you'll need to include the CGI library:
require 'cgi'
Once included, you can create a new CGI object:
cgi = CGI.new
One of the primary uses of CGI is to process form data. Ruby's CGI library makes this task straightforward:
name = cgi['name']
email = cgi['email']
This code retrieves the values of the 'name' and 'email' fields from a submitted form.
CGI scripts typically generate HTML responses. Ruby provides methods to simplify this process:
puts cgi.header
puts cgi.html {
cgi.head { cgi.title{"Welcome"} } +
cgi.body { cgi.h1{"Hello, #{name}!"} }
}
This example generates a complete HTML page with a header and a personalized greeting.
CGI provides access to various environment variables. These can be accessed through the CGI object:
request_method = cgi.request_method
remote_addr = cgi.remote_addr
These variables provide information about the request and the server environment.
Handling file uploads is another common task in CGI programming. Ruby's CGI library simplifies this process:
uploaded_file = cgi.params['file'].first
file_name = uploaded_file.original_filename
file_content = uploaded_file.read
This code snippet demonstrates how to access an uploaded file's name and content.
Ruby CGI programming offers a straightforward way to create dynamic web applications. While more modern frameworks like Ruby and HTTP are often preferred for larger applications, CGI remains useful for simple scripts and learning server-side programming concepts.
For more advanced web development in Ruby, consider exploring frameworks like Ruby on Rails or Sinatra, which build upon these fundamental CGI concepts.