Ruby on Rails For Dummies E-Book

Barry Burd

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 387

Veröffentlichungsjahr: 2011

Beschreibung

Quickly create Web sites with this poweful tool Use this free and easy programming language for e-commerce sites and blogs If you need to build Web and database applications quickly but you don't dream in computer code, take heart! Ruby on Rails was created for you, and this book will have you up and running in no time. The Ruby scripting language and the Rails framework let you create full-featured Web applications fast. It's even fun! Discover how to * Install and run Ruby and Rails * Use the RadRails IDE * Create a blog with Ruby * Connect your Web site to a database * Build a shopping cart * Explore Ruby's syntax

Leseprobe

Ruby on Rails™ For Dummies®

by Barry Burd

Ruby on Rails™ For Dummies®

Published byWiley Publishing, Inc.111 River St.Hoboken, NJ 07030-5774www.wiley.com

Copyright © 2007 by Wiley Publishing, Inc., Indianapolis, Indiana

Published by Wiley Publishing, Inc., Indianapolis, Indiana

Published simultaneously in Canada

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Library of Congress Control Number: 2006936826

ISBN: 978-0-470-08120-4

Manufactured in the United States of America

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About the Author

Dr. Barry Burd received an M.S. degree in Computer Science at Rutgers University and a Ph.D. in Mathematics at the University of Illinois. As a teaching assistant in Champaign-Urbana, Illinois, he was elected to the university-wide “List of Teachers Ranked as Excellent by Their Students” five times.

Since 1980, Dr. Burd has been a professor in the Department of Mathematics and Computer Science at Drew University in Madison, New Jersey. When he’s not lecturing at Drew University, Dr. Burd leads training courses for professional programmers in business and industry. He has lectured at conferences in the United States, Europe, Australia, and Asia. He is the author of several articles and books, including Java For Dummies, 4th Edition, and JSP: JavaServer Pages, both from Wiley Publishing, Inc.

Dr. Burd lives in Madison, New Jersey, with his wife and two children. In his spare time, he enjoys being a workaholic.

Dedication

for Harriet, Sam and Jennie, Sam and Ruth, Abram and Katie, Benjamin and Jennie

Author’s Acknowledgments

Many thanks to Paul Levesque who worked so closely with me on this project, and thanks to Katie Feltman who headed up the project at Wiley. And to Andy Cummings who steers the For Dummies series, thanks. And, yes, thanks to copy editors Mary Lagu and Virginia Sanders. Also, thanks to Laura Lewin, agent at StudioB. Thanks, and thanks again to Jay Zimmerman and the speakers in the No Fluff, Just Stuff Symposium for opening my eyes to Ruby on Rails. And to Charles Nutter and Thomas Enebo, who bridge the gap between Ruby and Java, thanks. Of course, Matt Kent, Kyle Shank, and Marc Baumbach, thanks for the use of RadRails, both inside and outside of this book. I extend thanks to Stefan Reichert with his Wicked Shell. To Francis Hwang and the members of the Ruby-NYC group, I say thanks. Thanks indeed to Frank Greco and his New York Java Special Interest Group and to Mike Redlich and the gang at the Amateur Computer Group of New Jersey because without them I wouldn’t know anything about object-relational mapping. Thanks. And special thanks to Sam and Jennie, and of course, to Harriet, thanks I say thanks I will Thanks.

Publisher’s Acknowledgments

We’re proud of this book; please send us your comments through our online registration form located at www.dummies.com/register/.

Some of the people who helped bring this book to market include the following:

Acquisitions, Editorial, and Media Development

Senior Project Editor: Paul Levesque

Acquisitions Editor: Katie Feltman

Copy Editors: Mary Lagu, Virginia Sanders

Technical Editor: Charles Nutter

Editorial Manager: Leah Cameron

Media Development Specialists: Angela Denny, Kate Jenkins, Steven Kudirka, Kit Malone

Media Development Coordinator: Laura Atkinson

Media Project Supervisor: Laura Moss

Media Development Manager: Laura VanWinkle

Editorial Assistant: Amanda Foxworth

Sr. Editorial Assistant: Cherie Case

Cartoons: Rich Tennant (www.the5thwave.com)

Composition Services

Project Coordinator: Erin Smith

Layout and Graphics: Claudia Bell, Lavonne Cook, Denny Hager, Barbara Moore, Barry Offringa, Laura Pence, Heather Ryan

Proofreaders: Cynthia Fields, Jessica Kramer, Techbooks

Indexer: Techbooks

Anniversary Logo Design: Richard Pacifico

Publishing and Editorial for Technology Dummies

Richard Swadley, Vice President and Executive Group Publisher

Andy Cummings, Vice President and Publisher

Mary Bednarek, Executive Acquisitions Director

Mary C. Corder, Editorial Director

Publishing for Consumer Dummies

Diane Graves Steele, Vice President and Publisher

Joyce Pepple, Acquisitions Director

Composition Services

Gerry Fahey, Vice President of Production Services

Debbie Stailey, Director of Composition Services

Contents

Title

Introduction

How to Use This Book

Conventions Used in This Book

What You Don’t Have to Read

Foolish Assumptions

How This Book Is Organized

Icons Used in This Book

Where to Go from Here

Part I : Nuts and Bolts

Chapter 1: Welcome to the World of Ruby on Rails

The Software Development Process

Along Comes Ruby on Rails

Let’s Get Going

Chapter 2: Installing the Software

Six Pieces of Software

Installing the Ruby Interpreter

Installing Rails

Installing Java

Installing RadRails

Installing MySQL

Installing MySQL Administrator

Chapter 3: Details on Rails

Creating a Database

Creating a New Ruby on Rails Project

Running Your New Rails Project (Already!)

Creating a Model

Creating a Database Table

Creating a Scaffold

Using the New Web Interface

Chapter 4: Using RadRails

Words, Words, Words

Some Common RadRails Tasks

Troubleshooting the Run of a Ruby Program

Part II : Creating Code

Chapter 5: Ruby One’s Day

Hello, Again

Working with Values

Going with the Flow

Bunches of Things

Using Methods

Chapter 6: Ruby Two’s Day

Objects and Classes

Objects Have Methods

Enhancing Classes

Creating a Module

Chapter 7: Weaving the Web

The Working of the Web

Your HTML Starter Kit

HTML Elements

Part III : Real Rails

Chapter 8: Action-Packed Adventures

Model/View/Controller

The Rails Way of Life

Writing What You Want Where You Want It

The Controller Shakes Hands with the View

Dividing the Work of the View

Chapter 9: Some Things You Can Do with Models

A Web Site for Photos

Programming with a Rails Model

Modifying a Database

More Rails Programming Tricks

Chapter 10: I’ve Been Working on the Rails Code

Displaying an Image

Importing Files

Chapter 11: Image Is Everything

Enhancing Your Project’s Code

Understanding the Enhanced Code

Chapter 12: More Model Magic

Blogging Your Dreams

Validating the Visitor’s Input

Adding Comments

Adding Keywords

Chapter 13: Cool Things on Rails

Using Ajax

Sending E-Mail

Creating and Consuming Web Services

Part IV : The Part of Tens

Chapter 14: Ten (Times Two) Great Web Sites

Ten Ruby Sites

Ten Rails Sites

Chapter 15: Ten Features That Set Ruby Apart

Hashes

Open Classes

Duck Typing

Modifiers

Blocks

Everything Is an Object

Objects Might Have Their Own Methods

Mixins

Built-In Unit Testing

Built-In Reflection

Chapter 16: Ten Pivotal Ruby on Rails Concepts

Don’t Repeat Yourself (DRY)

Convention over Configuration

Model/View/Controller (MVC)

Agile Development

Dynamic Discovery of a Database’s Characteristics

Object-Relational Mapping (ORM)

Using Generators

Create, Read, Update, and Delete (CRUD)

Using Migrations

Using Partials

Chapter 17: Ten Ways to Override Rails Defaults

Overriding the Database Name

Overriding a Database Table Name

Overriding a Controller Name

Overriding the Name of a Table’s Primary Key

Using Singular Nouns

Creating Irregular Plurals

Overriding a Default Layout

Creating Additional Web Pages

Modifying the Meanings of URLs

Changing the Server Environment

: Further Reading

Introduction

“R uby on Rails? What’s that?” asks my uncle. “You write about this stuff for dummies? You mean those black and yellow books that everyone buys?”

“Yes, like the one I’m quoting you in,” I say. “Please check your spelling as you speak.”

“I will. But what’s Ruby on Rails? Is it the 6:05 train to Poughkeepsie? Is it the name of an old vaudeville act? Is it a pop singer? A rock band? Is it a rare stone from India? Is it the codename of an informer in a political scandal?”

“No.”

“Is it the name of an exotic cocktail? A species of bird? An animal act in a circus? A John D. MacDonald title?”

Finally, I interrupt. “Ruby on Rails is a computer thing.”

“What kind of computer thing?” he asks.

“It’s a framework for creating applications with Web interfaces to databases.”

“Oh, yeah?” he says. “Your nephew from Brooklyn, he read Getting Ahead in Politics For Dummies. He loved the book. Did you write that one?”

How to Use This Book

As a computer book author, I strive not to be full of myself. I have no illusions that you plan on reading this book from cover to cover. I read sections and chapters out of order when I buy a computer book. Why would I expect you to approach my book any differently? And even if I read something in Chapter 2, who says I remember it when I read Chapter 11?

I write each section with these thoughts in mind. In the middle of Chapter 12, I might want you to remember some nugget of knowledge that I introduce in Chapter 4. If I use that nugget over and over again in Chapters 5, 7, 8, and 9, I don’t remind you about it in Chapter 12. But for other nuggets — ones that you don’t read about repeatedly in this book — I provide cross references.

So in general, my advice is

Read what interests you; skip what doesn’t interest you.

If you already know something, don’t bother reading about it.

If you’re curious, don’t be afraid to skip ahead. You can always sneak a peek at an earlier chapter if you really need to do so.

Conventions Used in This Book

Almost every technical book starts with a little typeface legend, and Ruby on Rails For Dummies is no exception. What follows is a brief explanation of the typefaces used in this book:

New terms are set in italics.

If you need to type something that’s mixed in with the regular text, the characters you type appear in bold. For example: “Type MyNewProject in the text field.”

You also see this computerese font. I use computerese for Ruby code, filenames, Web page addresses (URLs), on-screen messages, and other such things. Also, if something you need to type is really long, it appears in computerese font on its own line (or lines).

You need to change certain things when you type them. Words that you need to replace with your own words are set in italicized computerese. For instance, I might ask you to type

class Anyname

which means that you type class and then some name that you make up on your own.

What You Don’t Have to Read

Pick the first chapter or section that has material you don’t already know and start reading there. Of course, you might hate making decisions as much as I do. If so, here are some guidelines that you can follow:

If you already know what kind of an animal Ruby on Rails is and you know that you want to use Ruby on Rails, skip Chapter 1 and go straight to Chapter 2. Believe me, I won’t mind.

If you already have Ruby on Rails, a database, and a Ruby program editor installed on your computer, skip Chapter 2 and go to Chapter 3.

If you’ve seen one of the many Ruby on Rails demos or worked through a Ruby on Rails tutorial, move quickly through Chapter 3.

However, don’t completely ignore Chapter 3. Some of the wording I use in Chapter 3 might be helpful, even if you’ve already been through a Rails demo or two.

If you’re a computer programmer, you might have already used Eclipse (for Java or for some other programming language). In that case, plan a quick excursion through Chapter 4. This book’s examples use the RadRails integrated development environment, and RadRails is based on Eclipse.

If you’ve never written programs in Ruby, Perl, or Smalltalk, set aside some time to read Chapters 5 and 6.

These chapters cover some Ruby concepts, but the chapters don’t describe the entire Ruby language. In these chapters, I highlight Ruby concepts that appear frequently in Rails code. I also emphasize some unusual features of Ruby — features that you don’t find in other language families (in Java and C++, for example).

If you want to skip the sidebars and the Technical Stuff icons, please do. But try not to skip too many of my jokes. (I tell my kids that I write jokes for a living. They don’t believe me. But even so, I’d appreciate your help in perpetuating this myth.)

Foolish Assumptions

In this book, I make a few assumptions about you, the reader. If one of these assumptions is incorrect, you’re probably okay. If all these assumptions are incorrect . . . well, buy the book anyway.

I assume that you have access to a computer. Here’s the good news: You can run the code in this book on almost any computer. The only computers that you can’t use to run this code are ancient things that are more than six years old (give or take a few years).

I assume that you can navigate through your computer’s common menus and dialog boxes. You don’t have to be a Windows, Linux, or Macintosh power user, but you should be able to start a program, find a file, put a file into a certain directory . . . that sort of thing.

On those rare occasions when you need to drag and drop, cut and paste, or plug and play, I guide you carefully through the steps. But your computer might be configured in any of several billion ways, and my instructions might not quite fit your special situation. So, when you reach one of these platform-specific tasks, try following the steps in this book. If the steps don’t quite fit, consult a book with instructions tailored to your system or visit one of this book’s Web sites for helpful hints. The URLs are www.burdbrain.com/RubyOnRails and www.dummies.com/go/RonR1e.

I assume that you’ve written some computer programs. I’ve tried to make the book interesting for experienced programmers, yet accessible to people with only a modest amount of programming experience. I don’t assume that you’ve written programs in any particular language or that you’ve hacked from midnight until dawn on the latest UNIX system. I assume only that you can compose loops, if statements, and other such things. (Of course, if you have no computer programming experience, you can start with my Beginning Programming with Java For Dummies book. Remember, the more of my books that you buy, the less debt I’ll have when my kids finish college.)

If you’ve written lots of programs in Visual Basic, Java, or C++, you’ll discover some interesting plot twists in Ruby. The developer of Ruby took the best ideas in other programming languages, streamlined them, combined them, and reorganized them into a flexible, powerful new programming language. Ruby has many new, thought-provoking features. As you find out about these features, many of them will seem very natural to you. One way or another, you’ll feel good about using Ruby.

How This Book Is Organized

This book is divided into subsections, which are grouped into sections, which come together to make chapters, which are lumped finally into four parts. (When you write a book, you get to know your book’s structure pretty well. After months of writing, you find yourself dreaming in sections and chapters when you go to bed at night.) The parts of the book are listed here.

Part I: Nuts and Bolts

This part is your executive briefing. It includes a chapter that answers the question “What is Ruby on Rails?” and a chapter with a complete set of instructions on installing and running the software. It also has a jump-start chapter and a chapter with details about the RadRails integrated development environment.

Part II: Creating Code

Chapters 5 through 7 cover Ruby and HTML. Some of the material in Part II might be familiar to you. If so, you can skip some sections or read this stuff quickly. But don’t read too quickly. Ruby is a little different from some other programming languages, and you might stumble upon some exciting new ideas.

Part III: Real Rails

This third part cuts to the chase. Rails has three components — Action Controller, Action View, and Active Record. The controller controls things (of course), the view displays things, and Active Record maintains all the data. Chapters 8 through 13 cover these three components and describe some interesting applications along the way.

Part IV: The Part of Tens

The Part of Tens is a little Ruby on Rails candy store. In the Part of Tens, you can find lists — online resources, hints about Ruby, and other interesting goodies.

Icons Used in This Book

If you could watch me write this book, you’d see me sitting at my computer, talking to myself. I say each sentence in my head. Most of the sentences I mutter several times. When I have an extra thought, a side comment, or something that doesn’t belong in the regular stream, I twist my head a little bit. That way, whoever’s listening to me (usually nobody) knows that I’m off on a momentary tangent.

Of course, in print, you can’t see me twisting my head. I need some other way of setting a side thought in a corner by itself. I do it with icons. When you see a Tip icon or a Remember icon, you know that I’m taking a quick detour.

Here’s a list of icons that I use in this book.

A tip is an extra piece of information — something helpful that the other books may forget to tell you.

Everyone makes mistakes. Heaven knows that I’ve made a few in my time. Anyway, when I think people are especially prone to make a mistake, I mark it with a Warning icon.

Question: What’s stronger than a Tip icon, but not as strong as a Warning?

Answer: A Remember icon.

Occasionally I run across a technical tidbit. The tidbit might help you understand what the people behind the scenes (the people who developed Ruby on Rails) were thinking. You don’t have to read it, but you might find it useful. You might also find the tidbit helpful if you plan to read other (more geeky) books about Ruby on Rails.

This icon calls attention to useful material that you can find online.

Where to Go from Here

If you’ve gotten this far, you’re ready to start reading about Ruby on Rails. Think of me (the author) as your guide, your host, your personal assistant. I do everything I can to keep things interesting and, most importantly, help you understand.

If you like what you read, send me a note. My e-mail address, which I created just for comments and questions about this book, is [email protected]. And don’t forget — for the latest updates, visit one of this book’s support Web sites. The support sites’ addresses are www.burdbrain.com/RubyOnRails and www.dummies.com/go/RonR1e.

Part I

Nuts and Bolts

In this part . . .

What’s Ruby on Rails all about? And how do you install Ruby on Rails? And after installing it, how do you get started doing something with it? And what’s really going on at Area 51 in Roswell, New Mexico?

This first part of the book answers the basic questions about Ruby on Rails. But “basic” doesn’t mean “lame.” For example, in Chapter 3, you create a complete Web application from scratch. You create the application in minutes, not hours. Then in Chapter 4, you find out what’s at Area 51.

Chapter 2

Installing the Software

In This Chapter

Installing the required software

Testing that the software is installed properly

Adding shortcuts to run the software quickly and easily

There was a young fellow named Nash

Whose software installing was rash.

He followed directions,

But skipped half the sections,

And caused his computer to crash.

Your system won’t crash if you install Ruby on Rails incorrectly. The worst that can happen is that your Ruby program doesn’t run. Well, worse than that, your Ruby program doesn’t run, and you forget to send me an e-mail message asking me how to fix it. Remember, this author reads his e-mail!

Anyway, you don’t have to read all the sections in this chapter. (In the limerick, I encourage you to read all the sections, but I do that only because “sections” rhymes with “directions.” It makes a better limerick.) Instead, read enough directions to make sure you don’t leave out any crucial steps. That means skimming for what you need to know, skipping descriptions of things you already know how to do, and backtracking occasionally when you stumble onto some unusual computer behavior.

Six Pieces of Software

I recommend that you install six different programs when you begin working with Ruby on Rails. You can get away with fewer programs or different programs, but the list of programs in this chapter includes the easiest, most convenient tools, which are

The Ruby interpreter

The Rails framework

The Java runtime environment

The RadRails integrated development environment

The MySQL database system

The MySQL Administrator program

All of these tools are free. (Yippee!)

Installing the Ruby Interpreter