OReilly rails cookbook jan 2007 ISBN 0596527314

valuable cookbook will save you hundreds of hours when developing applications with Rails.... Rob's Rails Cookbook will hopefully do the same thing for those people just starting out wit

By Rob Orsini

Publisher: O'Reilly Pub Date: January 01, 2007 ISBN-10: 0-596-52731-4 ISBN-13: 978-0-596-52731-0 Pages: 600

Table of Contents | Index

The Rails Cookbook is is packed with the solutions you need to be a proficient developer

with Rails, the leading framework for building the new generation of Web 2.0 applications Recipes range from the basics, like installing Rails and setting up your development

valuable cookbook will save you hundreds of hours when developing applications with Rails.

By Rob Orsini

Publisher: O'Reilly Pub Date: January 01, 2007 ISBN-10: 0-596-52731-4 ISBN-13: 978-0-596-52731-0 Pages: 600

Copyright © 2007, O'Reilly Media All rights reserved

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errors or omissions, or for damages resulting from the use ofthe information contained herein

When Rob asked me to write the foreword for his book I jumped

at the chance Actually, I jumped at telling him I'd write theforeword and then I got distracted with billions of things andhad to finally get it down in a flash of brilliance Trust me, it'sbrilliant This foreword will change your life, cure baldness, giveyour enemies lymphoma, and nuns will recite it to their classes

as a reward for good behavior It's that good

The reason I wanted to write a foreword for a cookbook, and

specifically for Rails Cookbook, is that I wouldn't be here today

if it weren't for this type of book When learning to write code,administer systems, or cook fish the young junior will typicallyrun out and get your basic introductory books These books trytake the newbie through a fixed road of learning that coversmost topics lightly in the curriculum At first this is great, andthe junior learns a lot of "bootstrap knowledge" with the things

he didn't know he didn't know getting filled in like grout overbroken tile

After this initial learning though, these books are fairly uselessbecause they are horrible references If you read them straightthrough and put stickies on the important pages you might getsomething out of it Having to troll through one of these densetomes to find that thing you thought you remembered in

chapter maybe 8 or 9 sucks really bad at 2 a.m Been there,done that, bought the pajamas in lime green

This is where the "cookbook" genre comes into play, and whythese types of books made me a better programmer The one

Perl helped me take charge of a wildly managed heterogeneousnetwork of computers, and the cookbook helped me tame thewild Perl Perl was also my first light foray into CGI

programming and processing for the Web It was a great way tolearn CGI too, because all the nasty stuff was already takencare of, and Perl had all the gear you needed to program backthen Oh, I remember <blink> fondly

I'd have to say I didn't learn any Perl until I bought my copy ofthe cookbook, slammed it and a case of soda on a table, andspent an entire night writing a program to look for maliciousattacks in my system logs I'd read a few good books, but itwas the ability to ask a question, get an answer, then

implement the solution that taught me real Perl coding Best ofall, I could apply a technique, read about how it worked, andthen totally forget about it, only leaving a tiny marker in mybrain saying where to look it up again

With my Perl Cookbook I became a rock star geek in my own

little way My peers would spend hours trying to solve a

problem, and I'd just look it up and bang it out with Perl in afew minutes I could manage huge numbers of systems withsimple automation I even learned to appreciate some of thequirks of Perl for what they were

Why would I be talking about Perl in a Rails Cookbook

foreword? Well, apart from the fact that Rob said I could say

anything in the foreword, the Perl Cookbook was the one that

set the standard for me It doesn't matter what language it wasabout; what mattered was that this one book made me a

competent Perl programmer and system automator where

nearly all other books fell flat It's a great example of the

synergy of a set of components making the whole greater

The power of a good cookbook is its ability to impart expertknowledge in digestible chunks to beginners Just like with real

practicing and doing expert activities and hopefully teaches

them the right way to do the tricks of the trade

Rob's Rails Cookbook will hopefully do the same thing for those

people just starting out with their first Ruby on Rails project Italso will be a good reference for those "beginning

intermediates" who still have to look things up they rarely use

or haven't done before It's also great for crusty old guys like

me who can't even remember what we had for breakfast thatmorning

Zed A Shaw, creator of Mongrel and MUDCRAP-CE Master Black Belt Sifu, (http://www.zedshaw.com)

I've been a full time web developer since 1998, and have

worked with just about every popular web scripting languageover the years During the dot-com boom, I kept busy in webconsulting shops, trying to turn various entrepreneurial ideasinto profitable web businesses The boom was a very interestingtime; the collective excitement over some of the first popularweb applications was infectious I wrote a lot of code duringthat time, some of which was a mess, but it was fun, and it was

an introduction to a career that I enjoy tremendously

When the dot-com bubble crashed, the tone of the industry

changed dramatically Web work dried up drastically, and theoverall enthusiasm of the industry seemed to sink into recessionalong with the industry's economy I managed to chain togethervarious web programming gigs, but the work was not as

interesting as it had been when people had more money to

experiment with new ideas

In 2004, I landed a job as the webmaster at Industrial Lightand Magic At ILM, I worked mostly with Perl and Java, but thiswas also where I was introduced to Python Toward the end of

my time at ILM, I began to hear about Ruby and a lot of thebuzz on the Net about it versus Pythonboth being very capableand lightweight dynamic languages While at ILM, I was

immersed in the excitement of the visual effects industry andmanaged to wait out the bad economy until finally landing asoftware engineering position at O'Reilly Media It was at

O'Reilly that I first found out about Rails

Around the time I started at O'Reilly, something very significanthappened: Google released Google Maps The economy hadbeen slowly recovering, but it was the release of this one webapplication that re-ignited my excitement about web

applications and their development What was so interesting

technology It was just an incredibly creative use of

technologies that had been around for years

Being able to drag a map around seemed to shatter all previousassumptions about the limitations of web software After seeingthis application, and a number of others that were cropping up

at the time, my view of the potential of the Web, as well as myenthusiasm in developing it, was reborn Now, if I could justhave the same feeling about the tools I was using

That's when I discovered Rails and simultaneously, Ruby For

me, discovering and learning Rails had a similar effect to GoogleMaps; it seemed almost too good to be true Rails handled all ofthe things that I found most unpleasant about web

development automatically or so elegantly that they were nolonger painful The next thing I noticed was how easily new

projects were organized according to the MVC design pattern

I had worked on many MVC projects before, but often they

were home-grown and not easily reusable In some cases, theamount of setup involved made the benefits of using MVC

questionable, especially for smaller projects I've often said thatthe simple act of creating a Rails project felt like there was aroom full of experienced software veterans imparting their

knowledge about sound application design, ensuring that myproject started off in the right direction

I soon realized that nothing about the Rails framework or thebest practices encouraged by the Rails community was

particularly new In fact, most of the techniques and

methodologies involved have been around for years What Ifound special about Rails was that all of these things had cometogether, in sort of a perfect storm of best practices The resultwas a framework that made web development both enjoyableand rewarding

With a number of Rails projects behind me, I started doing talks

Who This Book Is For

In preparation for writing this book, I tried to collect a lot ofdata about what the Rails community needed most in a

cookbook To do this I collected data from the Rails mailing lists

as well as from the most active IRC channels I wasn't very

scientific about how I processed the data, but I did get a feel forwhat were many of the most commonly asked questions Based

on this, I created an initial outline, and then ran it past as manypeople as I could find, who reviewed and further edited it

The outline has evolved since I first presented it to my editor,but it still targets the needs of the bulk of the Rails community.The target reader for this book is someone with web

development experience, but perhaps new to Rails, or an

intermediate Rails developer

That said, I believe that much of the information I present isgoing to be valuable across the board; for example, Rails

application deployment is a universal problem that all Rails

developers need to solve In the end, I hope that everyone whoreads this book will find it significantly useful

Hibbs (O'Reilly)

Some code samples have filenames mentioned before the code;the files that accompany the code can be found on the book'sweb page at http://www.oreilly.com/catalog/9780596527310

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Used for file and directory names, email addresses, andURLs, as well as for new terms where they are defined

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Used for code listings and for keywords, variables,

functions, command options, database names, parameters,class names, and HTML tags where they appear in the text

bold

Used to mark lines of output in code listings and commandlines to be typed by the user

documentation You do not need to contact us for permissionunless you're reproducing a significant portion of the code Forexample, writing a program that uses several chunks of codefrom this book does not require permission Selling or

distributing a CD-ROM of examples from O'Reilly books doesrequire permission Answering a question by citing this book

Incorporating a significant amount of example code from thisbook into your product's documentation does require

permission

We appreciate, but do not require, attribution An attributionusually includes the title, author, publisher, and ISBN For

example: "Rails Cookbook by Rob Orsini Copyright 2007

O'Reilly Media, Inc., 978-0-596-52731-0."

If you feel your use of code examples falls outside fair use orthe permission given above, feel free to contact us at

Comments and Questions

http://www.oreilly.com/catalog/9780596527310

To comment or ask technical questions about this book, sendemail to:

The book's biggest contributor, aside from myself, has been

Mike Loukides Mike's input was invaluable, whether he was

refactoring a confusing paragraph or offering an insight about

an idea I hadn't thought to include, he was there helping everystep of the way The great thing about working with Mike is that

conversation being a side-track of something else

Fifteen people contributed recipes to the book I'd like to pointout the three that helped me the most during the final stages ofthe process Diego Scataglini contributed the most recipes (12total) More importantly, he produced many of these recipeswith very short notice as I pushed to fit in more content beforethe final deadline Christian Romney and Ryan Waldron alsostepped up to the plate in the final stages and helped fill outand clean up much of the book's content During the final days,the three of us collaborated in #rorcb (a.k.a The War Room),where I was able to delegate a huge amount of work to each ofthem Their contribution was outstanding but, most importantly,

we had a great time in the process I'm grateful to everyonewho contributed recipes They include Ben Bleything, BlaineCook, Ryan Daigle, Bill Froelich, Evan Henshaw-Plath, Rick

Olson, Matt Ridenour, Dae San Hwang, Andy Shen, Joe Van

Dyk, Nicholas Wieland, and Chris Wong

More special thanks goes to Coda Hale for doing an excellentpass over the book resulting in several emails full of valuablesuggestions Also thanks to Evan Henshaw-Plath (rabble), ZedShaw, and Geoffrey Grosenbach (topfunky) for putting up withmany late night Rails questions and offering sound advice alongthe way

The tool that I settled on for collaborating with reviewers wasBeast (an excellent Rails forum written by Josh Goebel and RickOlson) A number of discussions happened there that definitelyimproved the book several times over I'm thankful to all whoreviewed my content and posted comments They include SamAaron, Anjan Bacchu, Tony Frey, Matt Grayson, Stephan

Kamper, Bin Li, Tom Lianza, Thomas Lockney, Matt McKnight,James Moore, Hartmut Prochaska, Andy Shen, Bill Spornitz,

During the initial months of writing I switched between severaldifferent writing environments I finally settled on editing

directly in DocBook Once I accumulated a certain amount ofcontent and needed to perform various transformations, I

quickly discovered the limits of my knowledge of XML

processing This is where Keith Fahlgren and Andrew Savikasstepped in with just the right XPath expression or XMLMind

macro to get the job done, which let me focus on writing

Writing a book is like nothing I've ever done before Because ofthat, I'm thankful that I was able to talk with my friends whohave written books about the process Those friends are KyleRankin, Andrew Savikas, and Tony Stubblebine

Finally, I want to thank my wife for helping make this projectpossible She essentially became a single parent for quite a bitlonger then she bargained for I am grateful for her support andencouragement

Recipe 1.8 Running Rails in Windows with Instant RailsRecipe 1.9 Updating Rails with RubyGems

Recipe 1.10 Getting Your Rails Project into Subversion

Since it first appeared in July 2004, Ruby on Rails has

revolutionized the process of developing web applications Ithas enabled web developers to become much faster and moreefficient, allowing for quicker application developmenta criticaladvantage in these days of "web time." How does Rails do it?There are a few reasons behind Rails' success:

Convention over configuration

Rather than forcing you to configure every aspect of yourapplication, Rails is full of conventions If you can followthose conventions, you can do away with almost all

configuration files and a lot of extra coding If you can'tfollow those conventions, you're usually no worse off thanyou were in your previous environment

Liberal use of code generation

Rails can write a lot of your code for you For example,

when you need a class to represent a table in your

database, you don't have to write most of the methods:Rails looks at the table's definition and creates most of theclass for you on the fly You can mix in many extensions toadd special behavior, and when you really need to, you canadd your own methods You'll find that you're writing only afraction as much code as you did with other web

frameworks

Don't repeat yourself (DRY)

to code behavior only once; you never (well, almost never)have to write similar code in two different places Why isthis important? Not because you type less, but becauseyou're less likely to make mistakes by modifying one chunk

of code, and not another

David Heinemeier Hansson and the other Ruby on Rails coredevelopers have learned from the mistakes of other web

application frameworks and taken a huge step forward Ratherthan provide an extremely complex platform that can solveevery problem out of the box if you can only understand it,Rails solves a very simple problem extremely well With thatsolution under your belt, you'll find that it's a lot easier to work

up to the hard problems It's often easier, in fact, to solve thehard problem for yourself with Rails than to understand someother platform's solution Want to find out whether Rails is

everything it's cracked up to be? Don't wait; try it If you're not

a Ruby developer yet, don't worry; you only need to know alimited amount of Ruby to use Rails I'd be willing to bet thatyou'll want to learn more, though

Problem

You know that Rails is an evolving open source project, and youwant to stay on top of the latest developments Where do youget your questions answered, and how do you know what newfeatures are being developed?

Solution

Like most popular open source projects, Rails has a number ofmailing lists that developers, system administrators, and otherinterested parties can join to stay abreast of the latest

developments These lists also have searchable archives thatwill help you understand the evolution of a feature Currently,the following mailing lists are available:

(http://colloquy.info), or for terminal fans, Irssi

(http://www.irssi.org)

One great place to ask questions and look for answers is RailsWeenie (http://rails.techno-weenie.net) This site uses a points-based system in an attempt to persuade people to answer morequestions, and to ask more sensible questions When you create

an account, you automatically receive five points You can offerthese points as a reward for questions you want answered Ifsomeone answers the question, they get the number of pointsyou offered Also, if you answer other people's questions, youget the number of points they offered It's not as responsive asIRC, but you're far more likely to get a more thorough answer

to your question

The Rails Forum (http://railsforum.com) is another active

community of Rails users, with members of all levels of Railsexperience

(RUGs) in your area (

http://www.ruby-lang.org/en/community/user-groups) If there isn't a local Railsgroup where you live, perhaps you can start one!

Lastly, a large part of the Rails community exists in the

blogosphere, where participants post anything from tutorials toexplorations of the latest new features of the framework as

they're being developed Two popular blogs that aggregate

individual Ruby and Rails blogs are http://www.rubycorner.comand http://www.planetrubyonrails.org

Discussion

The Rails community is relatively young, but strong and growingfast If you've got questions, there are plenty of people willing

to help you answer them They'll help you get the hang of Railsdevelopment, and you can return the favor by helping others oreven contributing to the project

The Rails mailing list has lots of traffic: currently about 400

messages per day This means that you can post a question andsoon have it buried under a screen full of newer messages Thetrick to coping with this information overload is to use very

clear and descriptive subject lines and problem descriptions

The #rubyonrails IRC channel is also very busy, but it is a greatresource for instant feedback Just make sure you respect

simultaneous conversations Rather than pasting code examplesinto the channel, post them to an external site (e.g.,

http://pastie.caboo.se) In fact, when you're in the IRC channelsimply say, "Hi pastie," and the pastie bot will send you a link towhere you can post your code

Section 1.2"

Problem

You're beginning to develope Rails applications, and you havequestions You need to find the latest documentation for Ruby,Rails, and RubyGems libraries

Solution

The documentation for the latest stable version of the Rails API

is online at http://api.rubyonrails.com A group of hardcoreRails developers also maintains documentation on the bleeding-edge version of Rails at http://caboo.se/doc The latest Rubydocumentation is always available at http://www.ruby-doc.org.Here you can find documentation on the Ruby Core library, theRuby Standard Library, and the C API In regards to third-partylibraries, a comprehensive set of RubyGems documentation isavailable at http://www.gemjack.com You can also view

documentation on any RubyGems you have installed on yourlocal system by starting the gem server with the following

you'll find a vast amount of user contributed content While

of it can be out of date or inaccurate

Of late, there's been a growing trend to consolidate essential

documentation into so-called cheatsheets A quick web searchfor Ruby, Rails, or Prototype cheatsheets should yield some

Last but not least, GotApi (http://www.gotapi.com) might best

be described as a documentation aggregator It's a very usefulsite for looking up not only Ruby and Rails documentation, butother related docs (like JavaScript and CSS)

Discussion

The API documentation can be a little awkward The format is

best suited for looking up the methods of a class or the options

of a specific method, and less helpful as an introduction to theframework One way to become familiar with the major

components of Rails via the API is to read the documentation

for each base class (e.g., ActionController::Base, ActiveRecord::Base)

As you become more proficient with Ruby and Rails, you'll

definitely want to browse the source code itself This experiencecan be a little overwhelming if you're new to the language or

the framework, but there's truly no substitute if you want to

understand how all the magic works behind the scenes

Mauricio Fernandez, a long-time Rubyist, keeps a self-study

guide to the Ruby source code on his web site

Problem

You want to install a MySQL relational database server to beused by your Rails applications

Solution

Windows

win32.zip from http://dev.mysql.com/downloads Depending onwhich version of MySQL you download, you should see either a

If you're a Windows user, download and unzip mysql-5.0.18-setup.exe file or a msi file Click on one of these to start the

installation wizard For most cases, you can select the standardconfiguration, which includes the mysql command-line client andseveral other administration utilities, such as mysqldump

By default, the installation wizard sets up MySQL as a servicethat starts automatically Another option is to have the installerinclude MySQL's binary directory in the Windows PATH, allowingyou to call the MySQL utilities from the Windows command line.Once the installation is complete, you can start up mysql as theroot user at the command prompt as shown in Figure 1-1

Figure 1-1 Interaction with MySQL from the

command prompt

Linux

highest numbered version of the gem that ends with (ruby)

Discussion

The recommended way to install MySQL on Linux is to use yourdistribution's package management system On a Debian

GNU/Linux system, package management is handled by dpkg,which is similar to the RPM system used by Red Hat

distributions The easiest way to administer dpkg is with the aptsuite of tools, which includes apt-cache and apt-get

Once you've got the MySQL server installed, you need to createone or more databases and users While it's convenient to

create a database from a script, to make it easy to recreatethere are also a number of GUI tools for setting up and

administering MySQL databases Get the official MySQL GUItools from http://dev.mysql.com/downloads Even if you create

command-line user interface) is included; if you prefer a GUIadministration tool, also include pgAdmin III.