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)

Extending the login script to update content

Now that we can login via a script, we can extend this script by adding code to update the website country data. The code used in this section is available at https://github.com/kjam/wswp/blob/master/code/chp6/edit.py and https://github.com/kjam/wswp/blob/master/code/chp6/login.py.

You may have already noticed an Edit link at the bottom of each country:

When logged in, clicking this link leads to another page where each property of a country can be edited:

We will make a script to increase the population of a country by one person every time it's run. The first step is to rewrite our login function to utilize Session objects. This will make our code cleaner and allow us to remain logged into our current session. The new code is as follows:

def login(session=None):
""" Login to example website.
params:
session: request lib session...