Book Image

Python Web Scraping - Second Edition

By : Katharine Jarmul
Book Image

Python Web Scraping - Second Edition

By: Katharine Jarmul

Overview of this book

The Internet contains the most useful set of data ever assembled, most of which is publicly accessible for free. However, this data is not easily usable. It is embedded within the structure and style of websites and needs to be carefully extracted. Web scraping is becoming increasingly useful as a means to gather and make sense of the wealth of information available online. This book is the ultimate guide to using the latest features of Python 3.x to scrape data from websites. In the early chapters, you'll see how to extract data from static web pages. You'll learn to use caching with databases and files to save time and manage the load on servers. After covering the basics, you'll get hands-on practice building a more sophisticated crawler using browsers, crawlers, and concurrent scrapers. You'll determine when and how to scrape data from a JavaScript-dependent website using PyQt and Selenium. You'll get a better understanding of how to submit forms on complex websites protected by CAPTCHA. You'll find out how to automate these actions with Python packages such as mechanize. You'll also learn how to create class-based scrapers with Scrapy libraries and implement your learning on real websites. By the end of the book, you will have explored testing websites with scrapers, remote scraping, best practices, working with images, and many other relevant topics.
Table of Contents (10 chapters)

The Login form

The first form we'll automate is the Login form, which is available at http://example.webscraping.com/user/login. To understand the form, we can use our browser development tools. With the full version of Firebug or Chrome Developer Tools, it is possible to simply submit the form and check what data was transmitted in the Network tab (similar to how we did in Chapter 5, Dynamic Content). However, we can also see information about the form if we use "Inspect Element" features:

The important parts regarding how to send the form are the action, enctype, and method attributes of the form tag, and the two input fields (in the above image we have expanded the "password" field). The action attribute sets the HTTP location where the form data will be submitted, in this case, #, which represents the current URL. The enctype attribute (or encoding type) sets the encoding used for the...