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)

Interacting with Forms

In earlier chapters, we downloaded static web pages that return the same content. In this chapter, we will interact with web pages which depend on user input and state to return relevant content. This chapter will cover the following topics:

  • Sending a POST request to submit a form
  • Using cookies and sessions to log in to a website
  • Using Selenium for form submissions

To interact with these forms, you'll need a user account to log in to the website. You can register an account manually at http://example.webscraping.com/user/register. Unfortunately, we can't yet automate the registration form until the next chapter, which deals with CAPTCHA images.

Form methods
HTML forms define two methods for submitting data to the server-GET and POST. With the GET method, data such as ?name1=value1&name2=value2 is appended to the URL, which is known as a "query string". The browser...