Introduction to Django

Great open source software almost always comes about because one or more clever developers had a problem to solve and no viable or cost effective solution available. Django is no exception. Adrian and Jacob have long since “retired” from the project, but the fundamentals of what drove them to create Django live on. It is this solid base of real-world experience that has made Django as successful as it is. In recognition of their contribution, I think it best we let them introduce Django in their own words (edited and reformatted from the original book). ## Introducing Django ### By Adrian Holovaty and Jacob Kaplan-Moss – December 2009 In the early days, Web developers wrote every page by hand. Updating a Web site meant editing HTML; a “redesign” involved redoing every single page, one at a time. As Web sites grew and became more ambitious, it quickly became obvious that that approach was tedious, time-consuming, and ultimately untenable. A group of enterprising hackers at NCSA (the National Center for Supercomputing Applications, where Mosaic, the first graphical Web browser, was developed) solved this problem by letting the Web server spawn external programs that could dynamically generate HTML. They called this protocol the Common Gateway Interface, or CGI, and it changed the Web forever. It’s hard now to imagine what a revelation CGI must have been: instead of treating HTML pages as simple files on disk, CGI allows you to think of your pages as resources generated dynamically on demand. The development of CGI ushered in the first generation of dynamic Web sites. However, CGI has its problems: CGI scripts need to contain a lot of repetitive “boilerplate” code, they make code reuse difficult, and they can be difficult for first-time developers to write and understand. PHP fixed many of these problems, and it took the world by storm – it’s now by far the most popular tool used to create dynamic Web sites, and dozens of similar languages and environments (ASP, JSP, etc.) followed PHP’s design closely. PHP’s major innovation is its ease of use: PHP code is simply embedded into plain HTML; the learning curve for someone who already knows HTML is extremely shallow. But PHP has its own problems; its very ease of use encourages sloppy, repetitive, ill-conceived code. Worse, PHP does little to protect programmers from security vulnerabilities, and thus many PHP developers found themselves learning about security only once it was too late. These and similar frustrations led directly to the development of the current crop of “third-generation” Web development frameworks. With this new explosion of Web development comes yet another increase in ambition; Web developers are expected to do more and more every day. Django was invented to meet these new ambitions. ## Django’s History Django grew organically from real-world applications written by a Web development team in Lawrence, Kansas, USA. It was born in the fall of 2003, when the Web programmers at the *Lawrence Journal-World*newspaper, Adrian Holovaty and Simon Willison, began using Python to build applications. The World Online team, responsible for the production and maintenance of several local news sites, thrived in a development environment dictated by journalism deadlines. For the sites – including LJWorld.com, Lawrence.com and KUsports.com – journalists (and management) demanded that features be added and entire applications be built on an intensely fast schedule, often with only days’ or hours’ notice. Thus, Simon and Adrian developed a time-saving Web development framework out of necessity – it was the only way they could build maintainable applications under the extreme deadlines. In summer 2005, after having developed this framework to a point where it was efficiently powering most of World Online’s sites, the team, which now included Jacob Kaplan-Moss, decided to release the framework as open source software. They released it in July 2005 and named it Django, after the jazz guitarist Django Reinhardt. This history is relevant because it helps explain two key things. The first is Django’s “sweet spot.” Because Django was born in a news environment, it offers several features (such as its admin site, covered in Chapter 6) that are particularly well suited for “content” sites – sites like Amazon.com, craigslist.org, and washingtonpost.com that offer dynamic, database-driven information. Don’t let that turn you off, though – although Django is particularly good for developing those sorts of sites, that doesn’t preclude it from being an effective tool for building any sort of dynamic Web site. (There’s a difference between being *particularly effective* at something and being *ineffective* at other things.) The second matter to note is how Django’s origins have shaped the culture of its open source community. Because Django was extracted from real-world code, rather than being an academic exercise or commercial product, it is acutely focused on solving Web development problems that Django’s developers themselves have faced – and continue to face. As a result, Django itself is actively improved on an almost daily basis. The framework’s maintainers have a vested interest in making sure Django saves developers time, produces applications that are easy to maintain and performs well under load. Django lets you build deep, dynamic, interesting sites in an extremely short time. Django is designed to let you focus on the fun, interesting parts of your job while easing the pain of the repetitive bits. In doing so, it provides high-level abstractions of common Web development patterns, shortcuts for frequent programming tasks, and clear conventions on how to solve problems. At the same time, Django tries to stay out of your way, letting you work outside the scope of the framework as needed. We wrote this book because we firmly believe that Django makes Web development better. It’s designed to quickly get you moving on your own Django projects, and then ultimately teach you everything you need to know to successfully design, develop, and deploy a site that you’ll be proud of.