Cookies are important for maintaining sessions and can be crucial for scraping websites that require login or keep track of user sessions. When scraping with Ruby, you can manage cookies by using various HTTP client libraries such as Net::HTTP, HTTParty, or Mechanize. Each of these libraries has its own way of handling cookies.
Here's how you can manage cookies with each of these libraries:
Net::HTTP
Ruby's standard library Net::HTTP can be used to handle cookies manually. You need to save the Set-Cookie headers from the response and then send them back with subsequent requests.
require 'net/http'
require 'uri'
uri = URI('http://example.com/login')
response = Net::HTTP.post_form(uri, 'username' => 'user', 'password' => 'pass')
# Extract cookies from the response
cookies = response.get_fields('Set-Cookie')
cookie_string = cookies.join('; ')
# Use the cookies for the next request
uri = URI('http://example.com/protected-page')
http = Net::HTTP.new(uri.host, uri.port)
request = Net::HTTP::Get.new(uri)
request['Cookie'] = cookie_string
response = http.request(request)
puts response.body
HTTParty
HTTParty is a gem that simplifies HTTP requests and also handles cookies for you. You can use the :cookies option to send cookies with your requests.
require 'httparty'
response = HTTParty.post('http://example.com/login', body: { username: 'user', password: 'pass' })
# HTTParty maintains the cookies returned by the server
cookies = response.request.options[:headers]["Cookie"]
response = HTTParty.get('http://example.com/protected-page', headers: { 'Cookie' => cookies })
puts response.body
Mechanize
Mechanize is another gem that is specifically designed for web scraping and automation. It automatically handles cookies between requests.
require 'mechanize'
agent = Mechanize.new
page = agent.post('http://example.com/login', 'username' => 'user', 'password' => 'pass')
# Mechanize automatically saves and sends cookies
page = agent.get('http://example.com/protected-page')
puts page.body
Mechanize makes it easy to manage cookies, as it mimics a web browser's behavior. It takes care of storing and sending cookies with each request you make using the Mechanize object.
When scraping websites, always make sure to respect the terms of service and privacy policies of the website, and to not overload the website's servers with a high number of requests in a short time.
