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Screen Scraping Guide To Get Started On Your Own Project Using Ruby

Kenneth Parker

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Published in Write Your Own Screen Scraper: A Screen Scraping Guide To Get Started On Your Own Project Using Ruby And Nokogiri With Examples

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Screen scraping is a powerful technique that allows you to extract data from websites. It's a common technique used for a variety of purposes, such as data mining, web research, and web automation. In this guide, we'll provide a comprehensive to screen scraping using Ruby, a popular programming language for web development.

Write Your Own Screen Scraper: A screen scraping guide to get started on your own project using Ruby and Nokogiri with examples

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Prerequisites

Basic understanding of Ruby programming language
A text editor or IDE
A web browser

Step 1: Choose a Ruby Gem

The first step in screen scraping with Ruby is to choose a Ruby gem. A Ruby gem is a reusable library of Ruby code that provides specific functionality. There are several Ruby gems available for screen scraping, but the most popular one is Nokogiri.

Nokogiri is a powerful HTML and XML parsing library that makes it easy to navigate and extract data from web pages. To install Nokogiri, run the following command in your terminal:

gem install nokogiri

Step 2: Make an HTTP Request

Once you have installed Nokogiri, you can start making HTTP requests to web pages. An HTTP request is a message that a client (such as your Ruby program) sends to a server (such as a website) to request data. To make an HTTP request in Ruby, you can use the Net::HTTP library.

require 'net/http'

uri = URI('https://example.com') res = Net::HTTP.get_response(uri)

The Net::HTTP.get_response method returns an HTTP response object. The response object contains the status code of the request, the headers of the response, and the body of the response. You can access the body of the response using the body attribute.

Step 3: Parse HTML

Once you have an HTTP response, you can start parsing the HTML. HTML is a markup language that describes the structure of a web page. To parse HTML in Ruby, you can use the Nokogiri library.

require 'nokogiri'

doc = Nokogiri::HTML(res.body)

The Nokogiri::HTML method parses the HTML in the response body and creates a document object. The document object represents the structure of the web page. You can use the document object to navigate and extract data from the web page.

Step 4: Extract Data

Once you have parsed the HTML, you can start extracting data from the web page. You can use the document object to access the different elements of the web page, such as the title, the headings, and the paragraphs.

title = doc.title headings = doc.css('h1, h2, h3') paragraphs = doc.css('p')

You can use the title attribute to access the title of the web page. You can use the css method to access the elements of the web page that match a CSS selector. The css method returns an array of elements. You can use the text attribute to access the text content of an element.

In this guide, we've provided a comprehensive to screen scraping using Ruby. We've shown you how to choose a Ruby gem, make an HTTP request, parse HTML, and extract data from a web page. With this knowledge, you can start building your own screen scraping projects.