Django Design Patterns and Best Practices Copyright © 2015 Packt Publishing All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews. Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book. Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information. First published: March 2015 Production reference: 1260315 Published by Packt Publishing Ltd. Livery Place 35 Livery Street Birmingham B3 2PB, UK. ISBN 978-1-78398-664-4 www.packtpub.com Cover image by Sandeep Somasekharan ([email protected]) [ FM-2 ] About the Author Arun Ravindran is an avid speaker and blogger who has been tinkering with Django since 2007 for projects ranging from intranet applications to social networks. He is a long-time open source enthusiast and Python developer. His articles and screencasts have been invaluable to the rapidly growing Django community. He is currently a developer member of the Django Software Foundation. Arun is also a movie buff and loves graphic novels and comics. I wish to thank my wife, Vidya for her constant support and encouragement. I was writing this book at an exciting and challenging time because we were expecting our second child - Nihar. My daughter Kavya also had to endure several solitary days, as her dad devoted to writing. A big thanks to all the wonderful people at Packt Publishing - Rebecca, Fahad, Vivek and many others who helped in the creation of this book. Truly appreciate the honest reviews by Krace, Shoubhik and Jai. Sincere thanks to Anil Menon for his inputs on the 'SuperBook' storyline. Eternally grateful to Sandy for letting us use his dazzling click of a Hummingbird titled 'Alive!' as the cover photo. I express my unending appreciation of the entire Django and Python community for being open, friendly and incredibly collaborative. Without their hard work and generosity, we would not have the great tools and knowledge that we depend on everyday. Last but not the least, special thanks to my parents and friends who have always been there to support me. [ FM-4 ] About the Reviewers Shoubhik Bose is a development engineer at IBM India Software Labs in IBM's security division. When not in the office, he is an independent researcher on healthcare technologies and contributes without profit to a social enterprise healthcare start-up named Mission Arogya as an architect. In 2011, he co-authored the Springer paper Service Crawling in Cloud Computing. He loves to explore "new age" programming languages, platforms, and development frameworks. Kracekumar Ramaraju is a geek and Python enthusiast. He uses Python for fun and profit. He currently works at Recruiterbox, where he uses Python and Django to build web applications and automate servers. He has worked on other frameworks, such as Flask. He has spoken at PyCon India and the BangPypers meetup group. He contributes to Python open source projects. He has a BTech degree in information technology. He occasionally blogs at http://kracekumar.com. I would like to thank Arun Ravindran and Packt Publishing for giving me an opportunity to review this book. [ FM-5 ] Jai Vikram Singh Verma is a passionate entrepreneur and technologist. A computer science engineer by education, he runs his own start-up called Startup Labs Infotech Pvt. Ltd. in Jaipur, Rajasthan, India. With a total of 7+ years of experience in architecting and developing scalable web applications using Python, Django, and related technologies, he is well versed with the ins and outs of web development. Startup Labs does web and mobile product development for clients across the world, and they are also cooking some nifty tech products to be released under their own banner soon. Apart from work, Jai likes playing table tennis, cooking, going for long walks (especially in Sydney), driving, and just chilling out with friends. I would like to thank Packt Publishing for giving me the opportunity to review this awesome book. [ FM-6 ] Table of Contents Preface vii Chapter 1: Django and Patterns 1 Why Django? 2 The story of Django 3 A framework is born 3 Removing the magic 4 Django keeps getting better 4 How does Django work? 5 What is a Pattern? 6 Gang of Four Patterns 7 Is Django MVC? 8 Fowler's Patterns 9 Are there more patterns? 10 Patterns in this book 11 Criticism of Patterns 11 How to use Patterns 12 Best practices 12 Python Zen and Django's design philosophy 12 Summary 13 Chapter 2: Application Design 15 How to gather requirements 15 Are you a story teller? 17 HTML mockups 18 Designing the application 19 Dividing a project into Apps 19 Reuse or roll-your-own? 20 My app sandbox 21 Which packages made it? 21 [ i ]