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Ruby - CGI Useful Methods

Quiz

CGI Class Methods

Here is a list of CGI Class methods −

Sr.No.	Methods with Description
1	CGI::new([ level="query"]) Creates a CGI object. Level may be one of the following options. If one of the HTML levels is specified, the following methods are defined for generating output conforming to that level − query − No HTML output generated html3 − HTML3.2 html4 − HTML4.0 Strict html4Tr − HTML4.0 Transitional html4Fr − HTML4.0 Frameset
2	CGI::escape( str) Escapes an unsafe string using URL-encoding.
3	CGI::unescape( str) Expands a string that has been escaped using URL-encoding.
4	CGI::escapeHTML( str) Escapes HTML special characters, including: & < >.
5	CGI::unescapeHTML( str) Expands escaped HTML special characters, including: & < >.
6	CGI::escapeElement( str[, element...]) Escapes HTML special characters in the specified HTML elements.
7	CGI::unescapeElement( str, element[, element...]) Expands escaped HTML special characters in the specified HTML elements.
8	CGI::parse( query) Parses the query and returns a hash containing its key-value pairs.
9	CGI::pretty( string[, leader=" "]) Returns a neatly formatted version of the HTML string. If leader is specified, it's written at the beginning of each line. The default value for leader is two spaces.
10	CGI::rfc1123_date( time) Formats the data and time according to RFC-1123 (for example, Tue, 2 Jun 2008 00:00:00 GMT).

CGI Instance Methods

Assuming c is an instance created by CGI::new. Now, here is a list of methods, which can be applied to this instance −

Sr.No.	Methods with Description
1	c[ name] Returns an array containing the value of the field name corresponding to name.
2	c.checkbox( name[, value[, check = false]]) c.checkbox( options) Returns an HTML string defining a checkbox field. Tag attributes may be specified in a hash passed as an argument.
3	c.checkbox_group( name, value...) c.checkbox_group( options) Returns an HTML string defining a checkbox group. Tag attributes may be specified in a hash passed as an argument.
4	c.file_field( name[, size = 20[, max]]) c.file_field( options) Returns an HTML string defining a file field.
5	c.form([ method="post"[, url]]) { ...} c.form( options) Returns an HTML string defining a form. If a block is specified, the string produced by its output creates the contents of the form. Tag attributes may be specified in a hash passed as an argument.
6	c.cookies Returns a hash containing a CGI::Cookie object containing keys and values from a cookie.
7	c.header([ header]) Returns a CGI header containing the information in header. If header is a hash, its key-value pairs are used to create the header.
8	c.hidden( name[, value]) c.hidden( options) Returns an HTML string defining a HIDDEN field. Tag attributes may be specified in a hash passed as an argument.
9	c.image_button( url[, name[, alt]]) c.image_button( options) Returns an HTML string defining an image button. Tag attributes may be specified in a hash passed as an argument.
10	c.keys Returns an array containing the field names from the form.
11	c.key?( name) c.has_key?( name) c.include?( name) Returns true if the form contains the specified field name.
12	c.multipart_form([ url[, encode]]) { ...} c.multipart_form( options) { ...} Returns an HTML string defining a multipart form. If a block is specified, the string produced by its output creates the contents of the form. Tag attributes may be specified in a hash passed as an argument.
13	c.out([ header]) { ...} Generates HTML output. Uses the string produced by the block's output to create the body of the page.
14	c.params Returns a hash containing field names and values from the form.
15	c.params = hash Sets field names and values in the form using a hash.
16	c.password_field( name[, value[, size = 40[, max]]]) c.password_field( options) Returns an HTML string defining a password field. Tag attributes may be specified in a hash passed as an argument.
17	c.popup_menu( name, value...) c.popup_menu( options) c.scrolling_list( name, value...) c.scrolling_list( options) Returns an HTML string defining a pop-up menu. Tag attributes may be specified in a hash passed as an argument.
18	c.radio_button( name[, value[, checked = false]]) c.radio_button( options) Returns an HTML string defining a radio button. Tag attributes may be specified in a hash passed as an argument.
19	c.radio_group( name, value...) c.radio_group( options) Returns an HTML string defining a radio button group. Tag attributes may be specified in a hash passed as an argument.
20	c.reset( name[, value]) c.reset( options) Returns an HTML string defining a reset button. Tag attributes may be specified in a hash passed as an argument.
21	c.text_field( name[, value[, size = 40[, max]]]) c.text_field( options) Returns an HTML string defining a text field. Tag attributes may be specified in a hash passed as an argument.
22	c.textarea( name[, cols = 70[, rows = 10]]) { ...} c.textarea( options) { ...} Returns an HTML string defining a text area. If a block is specified, the string produced by its output creates the contents of the text area. Tag attributes may be specified in a hash passed as an argument.

HTML Generation Methods

You can create any HTML tag by using the corresponding HTML tag name along with any CGI instance. For example −

main.rb

require "cgi"
cgi = CGI.new("html4")
cgi.out {
   cgi.html {
      cgi.head { "\n"&plus;cgi.title{"This Is a Test"} } &plus;
      cgi.body { "\n"&plus;
         cgi.form {"\n"&plus;
            cgi.hr &plus;
            cgi.h1 { "A Form: " } + "\n"&plus;
            cgi.textarea("get_text") +"\n"&plus;
            cgi.br &plus;
            cgi.submit
         }
      }
   }
}

Output

Content-Type: text/html
Content-Length: 337

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"><HTML><HEAD>
<TITLE>This Is a Test</TITLE></HEAD><BODY>
<FORM METHOD="post" ENCTYPE="application/x-www-form-urlencoded">
<HR><H1>A Form: </H1>
<TEXTAREA NAME="get_text" COLS="70" ROWS="10"></TEXTAREA>
<BR><INPUT TYPE="submit"></FORM></BODY></HTML>

CGI Object Attributes

You can access any of the following attributes using a CGI instance −

Attribute	Returned Value
accept	Acceptable MIME type
accept_charset	Acceptable character set
accept_encoding	Acceptable encoding
accept_language	Acceptable language
auth_type	Authentication type
raw_cookie	Cookie data (raw string)
content_length	Content length
content_type	Content type
From	Client e-mail address
gateway_interface	CGI version string
path_info	Extra path
path_translated	Converted extra path
Query_string	Query string
referer	Previously accessed URL
remote_addr	Client host address
remote_host	Client hostname
remote_ident	Client name
remote_user	Authenticated user
request_method	Request method (GET, POST, etc.)
script_name	Program name
server_name	Server name
server_port	Server port
server_protocol	Server protocol
server_software	Server software
user_agent	User agent

ruby_web_applications.htm

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