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ails is a web application framework for the Ruby programming language. Rails is well thought out and practical. It will help you build powerful web sites quickly, with code that’s clean and easy to maintain.

or various reasons, Rails has gained an undeserved reputation of being difficult to install. We want to dispel this myth. The truth is that installing Rails is relatively easy and straightforward, provided you have all the right ingredients. Here, we’ll begin with an overview of what you’ll need to get Rails up and running, and then provide step-by-step instructions for actual installation. Finally, we’ll get you started with your first Rails application.

he best way to learn a programming language or a web framework is to dig in and write some code. After reading the first two chapters, you should have a good understanding of the Rails landscape. This chapter builds on that foundation by walking you through the construction of a basic application. You’ll learn how to create a database and how to connect it to Rails, as well as how to use a web interface to get data in and out of the application.

n the previous chapter, we took a whirlwind tour through creating a basic Rails application using the built-in scaffolding feature. We sketched out a basic model for our sample application, an event manager, and created the project databases. We used the built-in web server to deploy the application locally, and practiced adding and managing events from the web browser. In this chapter, we’re going to take a more in-depth look at how things work, starting with what is arguably the most important part of Rails: Active Record.

n the previous chapter, we introduced the basics of Active Record and how to use it. In this chapter, we’re going to delve more deeply into Active Record and teach you how to enhance your models.

hen you type a URL into your browser’s address bar and click enter, a few things happen behind the scenes. First, the URL is translated into a unique address by which the server that hosts the application can be identified. The request is then sent to that server, which begins a chain of events that culminates in a response. The response is usually, but not always, in the form of an HTML document, which is essentially a text document full of special codes that your browser understands and can render visually on your screen. At this point, the request cycle is complete, and the browser waits for further input from you. If you click a link somewhere on the page, or type a new URL in the address bar, the cycle begins all over again: the request is sent, the server processes it, and the server sends back the response.

jax represents a fundamental shift in what the web is capable of, and is one of the defining characteristics of the Web 2.0 movement. First coined by Jesse James Garrett in his essay, (), Ajax stands for Asynchronous JavaScript and XML. By enabling web applications to make requests to the server behind the scenes without refreshing the browser, Ajax can dramatically improve the responsiveness and usability of the user interface. It enables live searching, in-place editing, autocompletion, drag and drop re-ordering, and a host of interface techniques that were previously only available to desktop applications. While the acronym might be new, Ajax isn’t exactly new. In fact, it’s been around for several years. The problem was that it was prohibitively difficult to implement successfully. Times have changed, though, and with modern web frameworks like Rails, Ajax is accessible to the masses.

t’s a rare web application that doesn’t need to send mail from time to time. For example, you may want to send messages to welcome users who sign up to your site, relay passwords, or confirm orders placed with an online store. Rails ships with a library called Action Mailer, which provides developers with an easy-to-use yet powerful tool to handle email.

mart developers test their code. Take a minute to read that sentence again and let it sink in: smart developers test their code. The fact is, testing is one of the most important things you can do to improve the quality of your code, reduce the cost of change, and keep your software bug-free. Rails (and the Ruby community at large) takes testing seriously. Not surprisingly then, Rails goes out of its way to make testing hassle-free.

ails ships with a rich set of features and powerful functionality. It’s often said that Rails is designed to solve most problems most of the time. It can’t solve all problems or be all things to all people, and it doesn’t try to do that. Instead, it provides a mechanism to easily extend and augment the core functionality: . Plugins give developers the freedom to write extensions to Rails, without needing to include those additions in the Rails core code.