Beginning Rails: From Novice to Professional

386 Pages·2007·2.74 MB·English

by  Jeffrey Allan Hardy

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Beginning Rails:
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From Novice to Professional
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Beginning
Dear Reader, i
n
This book is for anyone who wants to learn how to develop web applications n
using the Rails framework for Ruby. Even if you have no prior programming i
n
experience or have never built a web application before, you’ll be able to get up
g
and running with Rails using this book. Starting with a thorough introduction Rails
to the Rails landscape, we’ll walk you though creating a working application,
from installation to deployment and everything in between. R
Rails is modular for a reason: software is easier to write and maintain when
it’s divided according to areas of concern. We think this approach applies to
a
teaching as well. That’s why each chapter in this book focuses on a specific
component of the framework. From modeling relationships with Active Record
to sending mail using Action Mailer, we show you how the components work i
together and where the lines of responsibility are drawn. We do this in a way l
that you can understand, by walking through code examples and explaining
s
why things are the way they are. The result is that you’ll know precisely how the
pieces fit together.
Rails is optimized for what most people need to do, most of the time, and
this book is no different. Our goal is to teach you the most important concepts
and no more. This is not an exhaustive reference, nor is it filled with ivory tower
From Novice to Professional
exercises. Instead, we’ve focused on the techniques that we, as Rails developers,
use on a daily basis.
In this book, you’ll find advice and practical solutions to common problems.
We’ll show you what we think are the best tools and techniques to use when
working with Rails, and what we’ve found to be best practices. We hope you’ll
find it useful, informative, and even entertaining.
Jeffrey Allan Hardy and Cloves Carneiro Jr.
A Beginner’s Guide to the Rails Framework for Ruby
Companion eBook
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C Jeffrey Allan Hardy Cloves Carneiro Jr.
SOURCE CODE ONLINE ISBN-13: 978-1-59059-686-9 a and
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www.apress.com ISBN-10: 1-59059-686-2 n
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53499 er with Hampton Catlin
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User level:
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Beginner–Intermediate
this print for content only—size & color not accurate spine = x.xxx" xxx page count
686-2 FM.qxd 6/30/07 9:04 AM Page i
Beginning Rails
From Novice to Professional
Jeffrey Allan Hardy and Cloves Carneiro Jr.
with Hampton Catlin
686-2 FM.qxd 6/30/07 9:04 AM Page ii
Beginning Rails: From Novice to Professional
Copyright © 2007 by Jeffrey Allan Hardy and Cloves Carneiro Jr.
All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means,
electronic or mechanical, including photocopying, recording, or by any information storage or retrieval
system, without the prior written permission of the copyright owner and the publisher.
ISBN-13 (pbk): 978-1-59059-686-9
ISBN-10 (pbk): 1-59059-686-2
Printed and bound in the United States of America 9 8 7 6 5 4 3 2 1
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Lead Editor: Chris Mills
Technical Reviewer: Hampton Catlin
Editorial Board: Steve Anglin, Ewan Buckingham, Gary Cornell, Jonathan Gennick, Jason Gilmore,
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686-2 FM.qxd 6/30/07 9:04 AM Page iii
For my best friend,Amy.
—Jeff
For Jane;you inspire me every morning.
—Cloves
686-2 FM.qxd 6/30/07 9:04 AM Page iv
686-2 FM.qxd 6/30/07 9:04 AM Page v
Contents at a Glance
About the Authors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
About the Technical Reviewer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxi
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiii
■ CHAPTER 1 Introducing the Rails Framework. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
■ CHAPTER 2 Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
■ CHAPTER 3 Getting Something Running. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
■ CHAPTER 4 Working with a Database:Active Record. . . . . . . . . . . . . . . . . . . . . . . . 65
■ CHAPTER 5 Advanced Active Record:Enhancing Your Models. . . . . . . . . . . . . . . 89
■ CHAPTER 6 Action Pack:Working with the View and the Controller. . . . . . . . . 133
■ CHAPTER 7 Improving Interaction with Ajax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
■ CHAPTER 8 Sending and Receiving Mail. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
■ CHAPTER 9 Testing Your Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
■ CHAPTER 10 Extending Rails with Plugins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
■ CHAPTER 11 Deploying Your Rails Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
■ APPENDIX A Ruby,a Programmer’s Best Friend . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
■ APPENDIX B Databases 101 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
■ APPENDIX C The Rails Community . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341
■ INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345
v
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Contents
About the Authors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
About the Technical Reviewer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxi
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiii
■ CHAPTER 1 Introducing the Rails Framework. . . . . . . . . . . . . . . . . . . . . . . . . . . 1
The Rise and Rise of the Web Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
The Web Is Not Perfect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
The Good Web Framework. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Enter Rails. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Rails Is Ruby. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Rails Encourages Agility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Rails Is Opinionated Software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Rails Is Open Source. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
The MVC Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
The MVC Cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
The Layers of MVC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
The Libraries That Make Up Rails. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Rails Is No Silver Bullet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
■ CHAPTER 2 Getting Started. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
An Overview of Rails Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Installing on Mac OS X 10.4 Tiger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Installing the Apple Developer Tools (Xcode). . . . . . . . . . . . . . . . . . . . 20
Installing MySQL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Adding MySQL to Your PATH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Installing Ruby . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
vii
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viii ■ CONTENTS
Installing RubyGems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Installing Rails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Automating Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Installing on Windows XP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Installing MySQL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Installing Ruby . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Installing Rails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Installing on Linux. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Installing MySQL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Installing Ruby . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Installing RubyGems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Installing Rails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Creating Your First Rails Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Starting the Built-In Web Server. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Generating a Controller. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Creating an Action. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Creating a Template . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
■ CHAPTER 3 Getting Something Running. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
An Overview of the Project. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Creating the Events Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Creating the Project Databases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Creating the Event Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Creating a Database Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Generating a Controller. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Up and Running with Scaffolding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Adding More Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Adding Validations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Generating a Scaffold. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
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■ CONTENTS ix
■ CHAPTER 4 Working with a Database: Active Record. . . . . . . . . . . . . . . . . . 65
Introducing Active Record:Object-Relational Mapping on Rails. . . . . . . . 66
What About SQL?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Active Record Conventions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Introducing the Console. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Active Record Basics:CRUD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Creating New Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Reading (Finding) Records. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Updating Records. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Deleting Records. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
When Good Models Go Bad. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
■ CHAPTER 5 Advanced Active Record: Enhancing Your Models. . . . . . . . 89
Adding Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Using Associations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Declaring Associations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Creating One-to-One Associations. . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Creating One-to-Many Associations. . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Applying Association Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Creating Many-to-Many Associations . . . . . . . . . . . . . . . . . . . . . . . . 107
Creating Rich Many-to-Many Associations. . . . . . . . . . . . . . . . . . . . 112
Building Conditions for Advanced Finding. . . . . . . . . . . . . . . . . . . . . . . . . . 115
Using a Conditions Hash. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Using a SQL Fragment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Using an Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Using Association Proxies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Applying Validations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Building Custom Validation Methods . . . . . . . . . . . . . . . . . . . . . . . . . 121
Using Built-in Validations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Making Callbacks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Reviewing the Updated Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Updating the User Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132