Book Image

Python Web Scraping Cookbook

By : Michael Heydt
Book Image

Python Web Scraping Cookbook

By: Michael Heydt

Overview of this book

Python Web Scraping Cookbook is a solution-focused book that will teach you techniques to develop high-performance scrapers and deal with crawlers, sitemaps, forms automation, Ajax-based sites, caches, and more. You'll explore a number of real-world scenarios where every part of the development/product life cycle will be fully covered. You will not only develop the skills needed to design and develop reliable performance data flows, but also deploy your codebase to AWS. If you are involved in software engineering, product development, or data mining (or are interested in building data-driven products), you will find this book useful as each recipe has a clear purpose and objective. Right from extracting data from the websites to writing a sophisticated web crawler, the book's independent recipes will be a godsend. This book covers Python libraries, requests, and BeautifulSoup. You will learn about crawling, web spidering, working with Ajax websites, paginated items, and more. You will also learn to tackle problems such as 403 errors, working with proxy, scraping images, and LXML. By the end of this book, you will be able to scrape websites more efficiently and able to deploy and operate your scraper in the cloud.
Table of Contents (13 chapters)

Caching responses

Scrapy comes with the ability to cache HTTP requests. This can greatly reduce crawling times if pages have already been visited. By enabling the cache, Scrapy will store every request and response.

How to do it

There is a working example in the 06/10_file_cache.py script. In Scrapy, caching middleware is disabled by default. To enable this cache, set HTTPCACHE_ENABLED to True and HTTPCACHE_DIR to a directory on the file system (using a relative path will create the directory in the project's data folder). To demonstrate, this script runs a crawl of the NASA site, and caches the content. It is configured using the following:

if __name__ == "__main__":
process = CrawlerProcess({
&apos...