# frozen_string_literal: true
# cgi.rb - cgi support library
# Copyright (C) 2000 Network Applied Communication Laboratory, Inc.
# Copyright (C) 2000 Information-technology Promotion Agency, Japan
# Author: Wakou Aoyama <wakou@ruby-lang.org>
# Documentation: Wakou Aoyama (RDoc'd and embellished by William Webber)
# The Common Gateway Interface (CGI) is a simple protocol for passing an HTTP
# request from a web server to a standalone program, and returning the output
# to the web browser. Basically, a CGI program is called with the parameters
# of the request passed in either in the environment (GET) or via $stdin
# (POST), and everything it prints to $stdout is returned to the client.
# This file holds the CGI class. This class provides functionality for
# retrieving HTTP request parameters, managing cookies, and generating HTML
# The file CGI::Session provides session management functionality; see that
# class for more details.
# See http://www.w3.org/CGI/ for more information on the CGI protocol.
# CGI is a large class, providing several categories of methods, many of which
# are mixed in from other modules. Some of the documentation is in this class,
# some in the modules CGI::QueryExtension and CGI::HtmlExtension. See
# CGI::Cookie for specific information on handling cookies, and cgi/session.rb
# (CGI::Session) for information on sessions.
# For queries, CGI provides methods to get at environmental variables,
# parameters, cookies, and multipart request data. For responses, CGI provides
# methods for writing output and generating HTML.
# Read on for more details. Examples are provided at the bottom.
# The CGI class dynamically mixes in parameter and cookie-parsing
# functionality, environmental variable access, and support for
# parsing multipart requests (including uploaded files) from the
# CGI::QueryExtension module.
# === Environmental Variables
# The standard CGI environmental variables are available as read-only
# attributes of a CGI object. The following is a list of these variables:
# AUTH_TYPE HTTP_HOST REMOTE_IDENT
# CONTENT_LENGTH HTTP_NEGOTIATE REMOTE_USER
# CONTENT_TYPE HTTP_PRAGMA REQUEST_METHOD
# GATEWAY_INTERFACE HTTP_REFERER SCRIPT_NAME
# HTTP_ACCEPT HTTP_USER_AGENT SERVER_NAME
# HTTP_ACCEPT_CHARSET PATH_INFO SERVER_PORT
# HTTP_ACCEPT_ENCODING PATH_TRANSLATED SERVER_PROTOCOL
# HTTP_ACCEPT_LANGUAGE QUERY_STRING SERVER_SOFTWARE
# HTTP_CACHE_CONTROL REMOTE_ADDR
# For each of these variables, there is a corresponding attribute with the
# same name, except all lower case and without a preceding HTTP_.
# +content_length+ and +server_port+ are integers; the rest are strings.
# The method #params() returns a hash of all parameters in the request as
# name/value-list pairs, where the value-list is an Array of one or more
# values. The CGI object itself also behaves as a hash of parameter names
# to values, but only returns a single value (as a String) for each
# For instance, suppose the request contains the parameter
# "favourite_colours" with the multiple values "blue" and "green". The
# following behavior would occur:
# cgi.params["favourite_colours"] # => ["blue", "green"]
# cgi["favourite_colours"] # => "blue"
# If a parameter does not exist, the former method will return an empty
# array, the latter an empty string. The simplest way to test for existence
# of a parameter is by the #has_key? method.
# HTTP Cookies are automatically parsed from the request. They are available
# from the #cookies() accessor, which returns a hash from cookie name to
# If a request's method is POST and its content type is multipart/form-data,
# then it may contain uploaded files. These are stored by the QueryExtension
# module in the parameters of the request. The parameter name is the name
# attribute of the file input field, as usual. However, the value is not
# a string, but an IO object, either an IOString for small files, or a
# Tempfile for larger ones. This object also has the additional singleton
# #local_path():: the path of the uploaded file on the local filesystem
# #original_filename():: the name of the file on the client computer
# #content_type():: the content type of the file
# The CGI class provides methods for sending header and content output to
# the HTTP client, and mixes in methods for programmatic HTML generation
# from CGI::HtmlExtension and CGI::TagMaker modules. The precise version of HTML
# to use for HTML generation is specified at object creation time.
# The simplest way to send output to the HTTP client is using the #out() method.
# This takes the HTTP headers as a hash parameter, and the body content
# via a block. The headers can be generated as a string using the #http_header()
# method. The output stream can be written directly to using the #print()
# Each HTML element has a corresponding method for generating that
# element as a String. The name of this method is the same as that
# of the element, all lowercase. The attributes of the element are
# passed in as a hash, and the body as a no-argument block that evaluates
# to a String. The HTML generation module knows which elements are
# always empty, and silently drops any passed-in body. It also knows
# which elements require matching closing tags and which don't. However,
# it does not know what attributes are legal for which elements.
# There are also some additional HTML generation methods mixed in from
# the CGI::HtmlExtension module. These include individual methods for the
# different types of form inputs, and methods for elements that commonly
# take particular attributes where the attributes can be directly specified
# as arguments, rather than via a hash.
# === Utility HTML escape and other methods like a function.
# There are some utility tool defined in cgi/util.rb .
# And when include, you can use utility methods like a function.
# value = cgi['field_name'] # <== value string for 'field_name'
# # if not 'field_name' included, then return "".
# fields = cgi.keys # <== array of field names
# # returns true if form has 'field_name'
# cgi.has_key?('field_name')
# cgi.has_key?('field_name')
# cgi.include?('field_name')
# CAUTION! cgi['field_name'] returned an Array with the old
# cgi.rb(included in Ruby 1.6)
# === Get form values as hash
# cgi.params['new_field_name'] = ["value"] # add new param
# cgi.params['field_name'] = ["new_value"] # change value
# cgi.params.delete('field_name') # delete param
# cgi.params.clear # delete all params
# === Save form values to file
# db = PStore.new("query.db")
# db["params"] = cgi.params
# === Restore form values from file
# db = PStore.new("query.db")
# cgi.params = db["params"]
# === Get multipart form values
# value = cgi['field_name'] # <== value string for 'field_name'
# value.read # <== body of value
# value.local_path # <== path to local file of value
# value.original_filename # <== original filename of value
# value.content_type # <== content_type of value
# and value has StringIO or Tempfile class methods.
# values = cgi.cookies['name'] # <== array of 'name'
# # if not 'name' included, then return [].
# names = cgi.cookies.keys # <== array of cookie names
# and cgi.cookies is a hash.
# for name, cookie in cgi.cookies
# cookie.expires = Time.now + 30
# cgi.out("cookie" => cgi.cookies) {"string"}
# cgi.cookies # { "name1" => cookie1, "name2" => cookie2, ... }
# cgi.cookies['name'].expires = Time.now + 30
# cgi.out("cookie" => cgi.cookies['name']) {"string"}
# === Print http header and html string to $DEFAULT_OUTPUT ($>)
# cgi = CGI.new("html4") # add HTML generation methods
# cgi.form("ACTION" => "uri") do
# cgi.textarea("get_text") +
# "params: #{cgi.params.inspect}\n" +
# "cookies: #{cgi.cookies.inspect}\n" +
# ENV.collect do |key, value|
# "#{key} --> #{value}\n"
# # add HTML generation methods
# CGI.new("html3") # html3.2
# CGI.new("html4") # html4.01 (Strict)
# CGI.new("html4Tr") # html4.01 Transitional
# CGI.new("html4Fr") # html4.01 Frameset
# CGI.new("html5") # html5
# === Some utility methods
# CGI.escapeHTML('Usage: foo "bar" <baz>')
# === Some utility methods like a function
# escapeHTML('Usage: foo "bar" <baz>')
# h('Usage: foo "bar" <baz>') # alias
CGI.autoload(:HtmlExtension, 'cgi/html')
It is recommended that you Edit text format, this type of Fix handles quite a lot in one request
