The Rails Way Free ebook download

Obie Fernandez, Series Editor

The Addison-Wesley Professional Ruby Series provides readers with practical, people-oriented, and in-depth information about applying the Ruby platform to create dynamic technology solutions. The series is based on the premise that the need for expert reference books, written by experienced practitioners, will never be satisfi ed solely by blogs and the Internet.

Books currently in the series

The Ruby Way: Solutions and Techniques in Ruby Programming, Second Edition Hal Fulton, ISBN 13: 9780672328848, ©2007

RailsSpace: Building a Social Networking Website with Ruby on Rails™ Michael Hartl & Aurelius Prochazka, ISBN 13: 9780321480798, ©2008

The Rails Way

Obie Fernandez, ISBN 13: 9780321445612, ©2008

Design Patterns in Ruby

Russ Olsen, ISBN 13: 9780321490452, ©2008

Short Cuts Rails Routing

David A. Black • 0321509242 • ©2007

Rails Refactoring to Resources: Using CRUD and REST in Your Rails Application Trotter Cashion • 0321501748 • ©2007

Mongrel: Serving, Deploying and Extending Your Ruby Applications Matt Pelletier and Zed Shaw • 0321483502 • ©2007

Rails Plugins: Extending Rails Beyond the Core James Adam • 0321483510 • ©2007

Rubyism in Rails

Jacob Harris • 0321474074 • ©2007

Troubleshooting Ruby Processes: Leveraging System Tools when the Usual Ruby Tricks Stop Working Philippe Hanrigou • 0321544684 • ©2008

Writing Effi cient Ruby Code

Dr. Stefan Kaes • 0321540034 • ©2008

Video

RailsSpace Ruby on Rails Tutorial (Video LiveLessons) Aurelius Prochazka • 0321517067 • ©2008

Ob

i

e Fernandez

The author and publi_{sher have taken care} i_{n the preparat}i_{on of th}i_{s book, but make no expressed or} i_mpli_{ed warranty of} any ki_{nd and assume no respons}i_bi_li_{ty for errors or om}i_ssi_ons. _{No l}i_abi_li_ty i_{s assumed for} i_nci_{dental or consequent}i_al dam-ages i_{n connect}i_{on w}i_{th or ar}i_si_{ng out of the use of the} i_nformati_{on or programs conta}i_{ned here}i_n.

The publi_{sher offers excellent d}i_{scounts on th}i_{s book when ordered} i_{n quant}i_{ty for bulk purchases or spec}i_{al sales, wh}i_ch may i_{nclude electron}i_{c vers}i_{ons and/or custom covers and content part}i_{cular to your bus}i_{ness, tra}i_ni_{ng goals, market}i_ng focus, and brandi_ng i_nterests. _{For more} i_nformati_{on, please contact}:

U._S. _{Corporate and Government Sales} (800) 382-3419

corpsales@pearsontechgroup._com For sales outsi_{de the Un}i_{ted States please contact}:

Internati_{onal Sales}

i_nternati_{onal@pearsoned}._com

This Book Is Safari Enabled

The Safari_{® Enabled} i_{con on the cover of your favor}i_{te technology book means the book} i_{s ava}i_lable through Safari _Bookshelf. _{When you buy th}i_{s book, you get free access to the onl}i_{ne ed}i_ti_{on for 45} days.

Safari _Bookshelf i_{s an electron}i_{c reference l}i_{brary that lets you eas}i_{ly search thousands of techn}i_{cal books, f}i_{nd code} sam-ples, download chapters, and access techni_cal i_nformati_{on whenever and wherever you need} i_t.

To gai_{n 45-day Safar}i _{Enabled access to th}i_{s book}: •_{Go to http}:_//www._awprofessi_onal._com/safari_enabled •_{Complete the br}i_{ef reg}i_strati_{on form}

•_{Enter the coupon code 52GH-T7VF-4T1U-ATFQ-DMJH}

If you have di_ffi_{culty reg}i_steri_{ng on Safar}i _{Bookshelf or access}i_{ng the onl}i_{ne ed}i_ti_{on, please e-ma}i_l customer-servi_ce@safari_booksonli_ne._com.

Vi_si_{t us on the Web}: _www._awprofessi_onal._com

Library of Congress Cataloging-in-Publication Data:

Fernandez, Obi_e.

The Rai_{ls way / Ob}i_{e Fernandez}. p. _cm.

Includes i_ndex.

ISBN 0-321-44561-9 (pbk.: _alk. _paper)

1. _{Ruby on ra}i_{ls (Electron}i_{c resource) 2}. _Object-ori_{ented programm}i_{ng (Computer sc}i_{ence) 3}. _{Ruby (Computer} pro-gram language) 4. _{Web s}i_{te development} . ₅. _Appli_cati_{on softare--Development}. _I. _Ti_tle.

QA76._{64F47 2007} 005._1'17--dc22

2007039880 Copyri_{ght © 2008 Pearson Educat}i_{on, Inc}.

All ri_{ghts reserved}. _Pri_nted i_{n the Un}i_{ted States of Amer}i_ca. _Thi_{s publ}i_cati_on i_{s protected by copyr}i_{ght, and perm}i_ssi_on must be obtai_{ned from the publ}i_{sher pr}i_{or to any proh}i_bi_{ted reproduct}i_{on, storage} i_{n a retr}i_{eval system, or transm}i_ssi_on i_n any form or by any means, electroni_{c, mechan}i_{cal, photocopy}i_{ng, record}i_{ng, or l}i_kewi_se. _For i_nformati_{on regard}i_{ng perm}i s-si_{ons, wr}i_{te to}:

ISBN-10: _{0-321-44561-9}

Text pri_nted i_{n the Un}i_{ted States on recycled paper at R}._R. _Donnelly i_{n Crawfordsv}i_{lle, IN}. Fi_{rst pr}i_nti_{ng November 2007}

Parts of thi_{s book conta}i_{n mater}i_{al excerpted from the Ruby and Ra}i_{ls source code and API documentat}i_{on, Copyr}i_{ght ©} 2004-2006 by Davi_{d He}i_nemei_{er Hansson under the MIT l}i_cense. _{Chapter 18 conta}i_{ns mater}i_{al excerpted from the RSpec} source code and API documentati_{on, Copyr}i_{ght © 2005-2007 The RSpec Development Team}.

The MIT License reads:

Permi_ssi_on i_{s hereby granted, free of charge, to any person obta}i_ni_{ng a copy of th}i_{s software and assoc}i_{ated documentat}i_on fi_{les (the “Software”), to deal} i_{n the Software w}i_{thout restr}i_cti_on, i_ncludi_{ng w}i_{thout l}i_mi_tati_{on the r}i_{ghts to use, copy,} mod-i_{fy, merge, publ}i_{sh, d}i_stri_{bute, subl}i_{cense, and/or sell cop}i_{es of the Software, and to perm}i_{t persons to whom the Software} i_{s furn}i_{shed to do so, subject to the follow}i_{ng cond}i_ti_ons:

The above copyri_{ght not}i_{ce and th}i_{s perm}i_ssi_{on not}i_{ce shall be} i_ncluded i_{n all cop}i_{es or substant}i_{al port}i_{ons of the} Software.

THE SOFTWARE IS PROVIDED “AS IS,” WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PAR-TICULAR PURPOSE, AND NONINFRINGEMENT. _{IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT} HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES, OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT, OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFT-WARE OR THE USE OF OR OTHER DEALINGS IN THE SOFTSOFT-WARE.

Associate Publisher Copy Editor

Mark Taub Margaret Berson

Acquisitions Editor Proofreader

Debra Wi_lli_{ams Cauley Kathy Ru}i_z

Development Editor

Songli_{n Q}i_u

Managing Editor

Patri_{ck Kanouse}

Senior Project Editor

San Dee Phi_lli_ps

Indexer

Ti_{m Wr}i_ght

Publishing Coordinator

Ci_{ndy Teeters}

Book Designer

Chuti _Prasertsi_th

Composition

Mark Shi_rar

Technical Reviewer

Contents

Chapter 1 Rails Environments and Configuration 1

Startup 2

Default Environment Settings 2

Mode Overri_{de 2} Rai_{ls Gem Vers}i_{on 2} Bootstrapping 3 RubyGems 5 Initializer 6

Default Load Paths 6

Rails, Modules, and Auto-Loading Code 7 Builtin Rails Info 8

Configuration 9

Ski_ppi_{ng Frameworks 9} Addi_ti_{onal Load Paths 10} Log-Level Overri_{de 10} Acti_{veRecord Sess}i_{on Store 10} Schema Dumper 11

Observers 11 Ti_{me Zones 11}

Additional Configuration 13

Development Mode 14

Automatic Class Reloading 15 The Rails Class Loader 15

Test Mode 17 Producti_{on Mode 17} Loggi_{ng 18}

Log File Analysis 22 Syslog 24

Conclusi_{on 25} References 25

Chapter 2 Working with Controllers 27

The Di_spatcher: _{Where It All Beg}i_{ns 28} Request Handling 28

Getting Intimate with the Dispatcher 29

Render unto Vi_{ew… 31} When in Doubt, Render 32 Explicit Rendering 33

Rendering Another Action’s Template 33 Rendering a Different Template Altogether 34 Rendering a Partial Template 35

Rendering Inline Template Code 35 Rendering Text 35

Rendering Other Types of Structured Data 36 :_{json 36}

:_{xml 36}

Rendering Nothing 36 Rendering Options 37

:_{content_type 37}

:_{layout 37}

:_{status 37}

Redi_recti_{ng 39}

Controller/Vi_{ew Commun}i_cati_{on 42} Fi_{lters 43}

Filter Inheritance 44 Filter Types 46

Filter Conditions 50 Filter Chain Halting 50

Streami_{ng 51}

send_data(data, options = {}) 51

Opti_{ons for send_data 51} Usage Examples 52

send_file(path, options = {}) 52

Opti_{ons for send_f}i_{le 53} Usage Examples 55

Letting the Web Server Send Files 55

Conclusi_{on 56} References 56

Chapter 3 Routing 57

The Two Purposes of Routi_{ng 58} Bound Parameters 60

Wi_{ldcard Components (“Receptors”) 61} Stati_{c Str}i_{ngs 62}

The routes._{rb F}i_{le 63} The Default Route 65 Spotlight on the :id Field 66 Default Route Generation 67 Modifying the Default Route 68

The Ante-Default Route and respond_to 69

respond_to and the HTTP-Accept Header 70

The Empty Route 71 Wri_ti_{ng Custom Routes 72} Usi_{ng Stat}i_{c Str}i_{ngs 72}

Usi_{ng Your Own “Receptors” 73} A Note on Route Order 75

Usi_{ng Regular Express}i_ons i_{n Routes 76} Default Parameters and the url_for Method 76

What Happened to :id? 77

Usi_{ng L}i_{teral URLs 79} Route Globbi_{ng 79}

Creating a Named Route 81

The Question of Using name_path Versus name_url 82 Considerations 83

What to Name Your Routes 83

Argument Sugar 84

A Little More Sugar with Your Sugar? 85

The Speci_{al Scope Method w}i_{th_opt}i_{ons 86} Conclusi_{on 88}

References 88

Chapter 4 REST, Resources, and Rails 89

REST i_{n a Rather Small Nutshell 89} REST i_{n Ra}i_{ls 91}

Routi_{ng and CRUD 92}

Resources and Representati_{ons 93} REST Resources and Rails 93

From Named Routes to REST Support 94 Reenter the HTTP Verb 96

The Standard RESTful Controller Acti_{ons 96} The PUT and DELETE Cheat 98

Singular and Plural RESTful Routes 98 The Special Pairs: new/create and edit/update 99

Si_{ngular Resource Routes 100} Nested Resources 101

Setting :path_prefix Explicitly 103 Setting :name_prefix Explicitly 103

Specifying RESTful Controllers Explicitly 105 All Together Now 105

Considerations 107 Deep Nesting? 108

RESTful Route Customi_zati_{ons 110} Extra Member Routes 110

Extra Collection Routes 111 Considerations 112

Controller-Only Resources 113

The respond_to Method 116 Formatted Named Routes 117

The RESTful Rai_{ls Act}i_{on Set 117} Index 118

Show 121 Destroy 121 New and Create 123 Edit and Update 124

Conclusi_{on 125} Reference 126

Chapter 5 Reflecting on Rails Routing 127

Exami_ni_{ng Routes} i_{n the Appl}i_cati_{on Console 127} Dumping Routes 128

Anatomy of a Route Object 129

Recognition and Generation in the Console 132 Named Routes in the Console 134

Testi_{ng Routes 135}

The Routi_{ng Nav}i_{gator Plug}i_{n 136} Conclusi_{on 137}

References 137

Chapter 6 Working with ActiveRecord 139

The Basi_{cs 140} Mi_grati_{ons 142}

Creating Migrations 143

Nami_{ng M}i_grati_{ons 144} Mi_grati_{on P}i_{tfalls 145} Migration API 146

create_table(name, opti_{ons) 147} Defining Columns 149

Column Type Mappi_{ngs 150} Column Opti_{ons 151} Deci_{mal Prec}i_si_{on 152} Column Type Gotchas 152 Custom Data Types 154

Convention over Configuration 156 Pluralization 157

Should I Report INFLECTOR Bugs to the Core Team? 158

Setting Names Manually 158 Legacy Naming Schemes 159

Defi_ni_{ng Attr}i_{butes 160} Default Attribute Values 160 Serialized Attributes 162

CRUD: _Creati_{ng, Read}i_{ng, Updat}i_{ng, Delet}i_{ng 163} Creating New ActiveRecord Instances 163

Reading ActiveRecord Objects 164

fi_{nd 164}

Reading and Writing Attributes 166

Hash Notati_{on 167} The attri_{butes Method 168}

Accessing and Manipulating Attributes Before They Are Typecast 168 Reloading 169

Dynamic Attribute-Based Finders 169 Custom SQL Queries 171

The Query Cache 172

Loggi_{ng 173}

Default Query Cachi_ng i_{n Controllers 173} Li_mi_tati_{ons 174}

Updating 174

Updating by Condition 176 Updating a Particular Instance 176 Updating Specific Attributes 177 Convenience Updaters 177 Controlling Access to Attributes 178 Deleting and Destroying 178

Database Locki_{ng 179} Optimistic Locking 180

Handli_{ng StaleObjectError 181} Pessimistic Locking 182

Considerations 183

Advanced Fi_ndi_{ng 183} Conditions 183

Random Orderi_{ng 186} Limit and Offset 186 Select Option 187 From Option 188 Group By Option 188 Locking Option 189

Joining and Including Associations 189 Read Only 189

Connecti_{ons to Mult}i_{ple Databases} i_{n D}i_{fferent Models 189} Usi_{ng the Database Connect}i_{on D}i_{rectly 191}

The DatabaseStatements Module 191

begi_{n_db_transact}i_{on() 191} commi_{t_db_transact}i_{on() 192} delete(sql_statement) 192 execute(sql_statement) 192 i_{nsert(sql_statement) 192}

reset_sequence!(table, column, sequence = ni_{l) 192} rollback_db_transacti_{on() 192}

select_all(sql_statement) 192 select_one(sql_statement) 193 select_value(sql_statement) 193 select_values(sql_statement) 193 update(sql_statement) 193

Other Connection Methods 194

acti_{ve? 194} adapter_name 195

di_{sconnect! and reconnect! 195} raw_connecti_{on 195}

supports_count_di_sti_{nct? 195} supports_mi_grati_{ons? 195} tables 195

veri_fy!(ti_{meout) 196}

Other Confi_gurati_{on Opt}i_{ons 196} Conclusi_{on 197}

Chapter 7 ActiveRecord Associations 199

The Associ_ati_{on H}i_{erarchy 199} One-to-Many Relati_onshi_{ps 201}

Adding Associated Objects to a Collection 203 AssociationCollection Methods 204

<<(*records) and create(attri_{butes = {}) 204} clear 205

delete(*records) and delete_all 205 destroy_all 206

length 206

replace(other_array) 206 si_{ze 206}

sum(column, *opti_{ons) 206} uni_{q 207}

The belongs_to Associ_ati_{on 207} Reloading the Association 208

Building and Creating Related Objects via the Association 208 belongs_to Options 209

:_{class_name 209}

:_condi_ti_{ons 210}

:_forei_{gn_key 213}

:_{counter_cache 213}

:i_{nclude 214}

:_polymorphi_{c => true 214}

The has_many Associ_ati_{on 215} has_many Options 216

:_{after_add 216}

:_{after_remove 216}

:_{as 216}

:_{before_add 217}

:_{before_remove 217}

:_{class_name 218}

:_condi_ti_{ons 218}

:_{counter_sql 218}

:_{dependent =>} :_{delete_all 219}

:_{dependent =>} :_{destroy_all 219}

:_{dependent =>} :_nulli_{fy 219}

:_exclusi_{vely_dependent 219}

:_{extend => Extens}i_{onModule 219}

:_fi_{nder_sql 219}

:_forei_{gn_key 219}

:_{group 220}

:i_{nclude 220}

:i_{nsert_sql 223}

:_li_mi_{t 223}

:_{offset 223}

:_{order 223}

:_{select 223}

:_{source and} :_{source_type 223}

:_{table_name 223}

:_{through 224}

:_uni_{q => true 224}

Proxy Methods 224

bui_ld(attri_{butes = {}) 224} count(*args) 225 fi_{nd(*args) 225}

Many-to-Many Relati_onshi_{ps 225} has_and_belongs_to_many 225

Self-Referenti_{al Relat}i_onshi_{p 226} Bi_di_recti_{onal Relat}i_onshi_{ps 227} Custom SQL Opti_{ons 229}

Extra Columns on has_and_belongs_to_many Joi_{n Tables 232} “Real Joi_{n Models” and habtm 232}

has_many :through 233

Joi_{n Models 233}

Usage Consi_derati_{ons and Examples 235} Aggregati_{ng Assoc}i_ati_{ons 236}

Joi_{n Models and Val}i_dati_{ons 237} has_many :through Options 238

:_{source_type 238}

:_uni_{q 240}

One-to-One Relati_onshi_{ps 241} has_one 241

has_one Options 244 :_{as 244}

:_{class_name 244}

:_condi_ti_{ons 245}

:_{dependent 245}

:_forei_{gn_key 245}

:i_{nclude 245}

:_{order 246}

Unsaved Objects and Associ_ati_{ons 246} One-to-One Associations 246

Collections 247

Associ_ati_{on Extens}i_{ons 247} The Associ_ati_{onProxy Class 249}

reload and reset 249

proxy_owner, proxy_reflecti_{on, and proxy_target 249} Conclusi_{on 250}

References 251

Chapter 8 ActiveRecord Validations 253

Fi_ndi_{ng Errors 253}

The Si_{mple Declarat}i_{ve Val}i_dati_{ons 254} validates_acceptance_of 254

Error Message 255 The accept Opti_{on 255} validates_associated 255 validates_confirmation_of 256 validates_each 256

validates_inclusion_of and validates_exclusion_of 257 validates_existence_of 257

Constrai_{nt Opt}i_{ons 260} Error Message Opti_{ons 260} validates_numericality_of 260 validates_presence_of 261

Vali_dati_{ng the Presence of Assoc}i_{ated Objects 261} validates_uniqueness_of 261

Enforci_{ng Un}i_{queness of Jo}i_{n Models 262} RecordInvalid 263

Common Vali_dati_{on Opt}i_{ons 263} :allow_nil 263

:if 263 :message 263 :on 264

Condi_ti_{onal Val}i_dati_{on 264} Usage and Considerations 265

Worki_{ng w}i_{th the Errors Object 266} Manipulating the Errors Collection 267

add_to_base(msg) 267 add(attri_{bute, msg) 267} clear 267

Checking for Errors 267 i_nvali_d?(attri_{bute) 267}

on(attri_{bute) 267} Custom Vali_dati_{on 268} Ski_ppi_{ng Val}i_dati_{ons 269} Conclusi_{on 270}

Reference 270

Chapter 9 Advanced ActiveRecord 271

Callbacks 271

Callback Registration 272

One-Li_{ners 273} Protected or Pri_{vate 273} Matched before/after Callbacks 274

Callback Usages 275

Cleani_{ng Up Attr}i_{bute Formatt}i_{ng w}i_{th before_val}i_{date_on_create 275} Geocodi_{ng w}i_{th before_save 275}

Paranoi_{a w}i_{th before_destroy 277}

Cleani_{ng Up Assoc}i_{ated F}i_{les w}i_{th after_destroy 277} Special Callbacks: after_initialize and after_find 278 Callback Classes 279

Multi_{ple Callback Methods} i_{n One Class 280} Testabi_li_{ty 282}

Observers 282

Naming Conventions 283 Registration of Observers 283 Timing 284

Si_{ngle-Table Inher}i_{tance (STI) 284} Mapping Inheritance to the Database 286 STI Considerations 288

STI and Associations 288

Abstract Base Model Classes 291

Polymorphi_{c has_many Relat}i_onshi_{ps 292} In the Case of Models with Comments 293

The Interface 293

The Database Columns 294

Has_many :_{through and Polymorph}i_{cs 295} Considerations about has_many 296

Modules for Reusi_{ng Common Behav}i_{or 296} A Review of Class Scope and Contexts 299 The included Callback 300

Modi_fyi_{ng Act}i_{veRecord Classes at Runt}i_{me 301} Considerations 303

Ruby and Domain-Specific Languages 303

Conclusi_{on 305} References 305

Chapter 10 ActionView 307

ERb Basi_{cs 308} ERb Practice 308

Commenting Out ERb Delimiters 310 Conditional Output 311

RHTML? RXML? RJS? 311

Layouts and Templates 312

Yielding Content 313 Template Variables 315

Instance Vari_{ables 315} assi_{gns 316}

base_path 316 controller 316 flash 317 headers 318 logger 318 params 319

request and response 319 sessi_{on 319}

Protecting the Integrity of Your View from User-Submitted Content 319

Parti_{als 320}

Simple Use Cases 321 Reuse of Partials 322 Shared Partials 323

Passing Variables to Partials 324

The local_assi_{gns Hash 325} Render Collections 325

The parti_{al_counter Var}i_{able 326} Shari_{ng Collect}i_{on Part}i_{als 326} Logging 327

Cachi_{ng 327}

Caching in Development Mode? 328 Page Caching 328

Action Caching 328

Desi_{gn Cons}i_derati_{ons 329} Fragment Caching 330

Avoi_di_{ng Extra Database Act}i_vi_{ty 333} Expiration of Cached Content 333

Expi_ri_{ng Pages and Act}i_{ons 333} Expi_ri_{ng Fragments 334}

Usi_{ng regular express}i_ons i_{n exp}i_rati_{on calls 334} Automatic Cache Expiry with Sweepers 335 Cache Logging 337

Action Cache Plugin 337 Cache Storage 338

Confi_gurati_{on Example 339}

Li_mi_tati_{ons of F}i_{le-Based Storage 339} Manual Sweepi_{ng w}i_{th rake 339} Conclusi_{on 340}

References 340

Chapter 11 All About Helpers 341

Acti_{veRecordHelper 342} Reporting Validation Errors 342

error_message_on(object, method, prepend_text = “”, append_text = “”, css_class = “formError”) 342

error_messages_for(*params) 343

Automatic Form Creation 344

form(name, opti_{ons) 344}

i_{nput(name, method, opt}i_{ons) 346}

Customizing the Way Validation Errors Are Highlighted 346

AssetTagHelper 348

Head Helpers 348

auto_di_{scovery_l}i_{nk_tag(type =} :_{rss, url_opt}i_{ons = {}, tag_opt}i_{ons = {}) 348} i_{mage_path(source) 350}

i_{mage_tag(source, opt}i_{ons = {}) 350}

javascri_{pt_}i_{nclude_tag(*sources) 351} javascri_{pt_path(source) 352}

stylesheet_li_{nk_tag(*sources) 352} stylesheet_path(source) 352

BenchmarkHelper 353

benchmark(message = “Benchmarki_{ng”, level =} :i_{nfo) 353} CacheHelper 353

CaptureHelper 354 capture(&block) 354

content_for(name, &block) 354 DateHelper 355

The Date and Time Selection Helpers 355

date_select(object_name, method, opti_{ons = {}) 355} dateti_{me_select(object_name, method, opt}i_{ons = {}) 356} ti_{me_select(object_name, method, opt}i_{ons = {}) 356} The Individual Date and Time Select Helpers 356

select_date(date = Date._{today, opt}i_{ons = {}) 357} select_dateti_me(dateti_{me = T}i_me._{now, opt}i_{ons = {}) 357} select_day(date, opti_{ons = {}) 357}

select_hour(dateti_{me, opt}i_{ons = {}) 357} select_mi_nute(dateti_{me, opt}i_{ons = {}) 357} select_month(date, opti_{ons = {}) 358} select_second(dateti_{me, opt}i_{ons = {}) 358} select_ti_me(dateti_{me, opt}i_{ons = {}) 358} select_year(date, opti_{ons = {}) 359}

Common Options for Date Selection Helpers 359

distance_in_time Methods with Complex Descriptive Names 359

di_{stance_of_t}i_{me_}i_{n_words(from_t}i_{me, to_t}i_{me = 0,} i_{nclude_seconds = false) 360} di_{stance_of_t}i_{me_}i_{n_words_to_now(from_t}i_me, i_{nclude_seconds = false) 361} DebugHelper 361

FormHelper 362

Creating Forms for ActiveRecord Models 362

Vari_{ables Are Opt}i_{onal 363}

Rai_{ls-Generated Form Convent}i_{ons 363} Di_splayi_{ng Ex}i_sti_{ng Values 364}

Updati_{ng Mult}i_{ple Objects at Once 364} Square Brackets wi_{th New Records? 365} Indexed Input Fi_{elds 366}

Faux Accessors 369

How Form Helpers Get Their Values 370

Select Helpers 371

collecti_{on_select(object, attr}i_{bute, collect}i_{on, value_method, text_method, opt}i_{ons = {},} html_opti_{ons = {}) 372}

country_select(object, attri_{bute, pr}i_ori_{ty_countr}i_{es = n}i_{l, opt}i_{ons = {}, html_opt}i_{ons = {})} 372

select(object, attri_{bute, cho}i_{ces, opt}i_{ons = {}, html_opt}i_{ons = {}) 372}

ti_{me_zone_select(object, method, pr}i_ori_{ty_zones = n}i_{l, opt}i_{ons = {}, html_opt}i_{ons = {}) 373} Option Helpers 373

country_opti_{ons_for_select(selected = n}i_{l, pr}i_ori_{ty_countr}i_{es = n}i_{l) 373}

opti_{on_groups_from_collect}i_{on_for_select(collect}i_{on, group_method, group_label_method,} opti_{on_key_method, opt}i_{on_value_method, selected_key = n}i_{l) 373}

opti_{ons_for_select(conta}i_{ner, selected = n}i_{l) 375}

opti_{ons_from_collect}i_{on_for_select(collect}i_{on, value_method, text_method, selected=n}i_l) 377

ti_{me_zone_opt}i_{ons_for_select(selected = n}i_{l, pr}i_ori_{ty_ zones = n}i_{l, model = T}i_{meZone) 377} FormTagHelper 378

check_box_tag(name, value = “1”, checked = false, opti_{ons = {}) 378} end_form_tag 378

fi_{le_f}i_{eld_tag(name, opt}i_{ons = {}) 378}

form_tag(url_for_opti_{ons = {}, opt}i_{ons = {}, *parameters_for_url, &block) 379} hi_{dden_f}i_{eld_tag(name, value = n}i_{l, opt}i_{ons = {}) 380}

i_{mage_subm}i_{t_tag(source, opt}i_{ons = {}) 380}

password_fi_{eld_tag(name = “password”, value = n}i_{l, opt}i_{ons = {}) 380} radi_{o_button_tag(name, value, checked = false, opt}i_{ons = {}) 380} select_tag(name, opti_{on_tags = n}i_{l, opt}i_{ons = {}) 380}

start_form_tag 380

submi_{t_tag(value = “Save changes”, opt}i_{ons = {}) 381} text_area_tag(name, content = ni_{l, opt}i_{ons = {}) 381} text_fi_{eld_tag(name, value = n}i_{l, opt}i_{ons = {}) 381} JavaScri_{ptHelper 381}

button_to_functi_{on(name, funct}i_{on, html_opt}i_{ons={}, &block) 381} defi_{ne_javascr}i_{pt_funct}i_{ons() 382}

escape_javascri_pt(javascri_{pt) 382}

javascri_{pt_tag(content, html_opt}i_{ons={}) 382}

li_{nk_to_funct}i_{on(name, funct}i_{on, html_opt}i_{ons={}, &block) 382} NumberHelper 383

human_si_ze(si_{ze, prec}i_si_{on=1) 383}

number_to_human_si_ze(si_{ze, prec}i_si_{on=1) 384} number_to_percentage(number, opti_{ons = {}) 384} number_to_phone(number, opti_{ons = {}) 385}

number_wi_{th_del}i_mi_{ter(number, del}i_mi_{ter=”,”, separator=”}._{”) 385} number_wi_{th_prec}i_si_{on(number, prec}i_si_{on=3) 385}

Pagi_nati_{onHelper 386} will_paginate 386 paginator 387 Paginating Find 388

RecordIdenti_fi_cati_{onHelper 388}

dom_class(record_or_class, prefi_{x = n}i_{l) 389} dom_i_{d(record, pref}i_{x = n}i_{l) 389}

parti_{al_path(record_or_class) 389} RecordTagHelper 390

content_tag_for(tag_name, record, *args, &block) 390 di_{v_for(record, *args, &block) 391}

TagHelper 391

cdata_secti_{on(content) 391}

content_tag(name, content = ni_{l, opt}i_{ons = n}i_{l, &block) 391} escape_once(html) 392

tag(name, opti_{ons = n}i_{l, open = false) 392} TextHelper 393

auto_li_{nk(text, l}i_{nk =} :_{all, href_opt}i_{ons = {}, &block) 393} concat(stri_{ng, b}i_ndi_{ng) 393}

cycle(fi_{rst_value, *values) 394}

excerpt(text, phrase, radi_{us = 100, excerpt_str}i_{ng = “}..._{”) 395}

hi_ghli_{ght(text, phrases, h}i_ghli_{ghter = ‘<strong class=”h}i_ghli_{ght”>\1</strong>’) 395} markdown(text) 396

plurali_{ze(count, s}i_{ngular, plural = n}i_{l) 396} reset_cycle(name = “default”) 397 sani_ti_{ze(html) 397}

si_{mple_format(text) 398} stri_{p_l}i_{nks(text) 398} stri_{p_tags(html) 398} texti_li_{ze(text) 399}

truncate(text, length = 30, truncate_stri_{ng = “}..._{”) 399} word_wrap(text, li_{ne_w}i_{dth = 80) 400}

UrlHelper 400

button_to(name, opti_{ons = {}, html_opt}i_{ons = {}) 400} current_page?(opti_{ons) 401}

li_{nk_to(name, opt}i_{ons = {}, html_opt}i_{ons = n}i_{l) 401}

li_{nk_to_}i_f(condi_ti_{on, name, opt}i_{ons = {}, html_opt}i_{ons = {}, &block) 403} li_{nk_to_unless(cond}i_ti_{on, name, opt}i_{ons = {}, html_opt}i_{ons = {}, &block) 403} li_{nk_to_unless_current(name, opt}i_{ons = {}, html_opt}i_{ons = {}, &block) 403} mai_{l_to(ema}i_{l_address, name = n}i_{l, html_opt}i_{ons = {}) 404}

url_for(opti_{ons = {}) 405} Relyi_{ng on Named Routes 406} Wri_ti_{ng Your Own Helpers 407}

Small Optimizations: The Title Helper 407

Encapsulating View Logic: The photo_for Helper 408 Smart View: The breadcrumbs Helper 409

Wrappi_{ng and General}i_zi_{ng Part}i_{als 410} A tiles Helper 410

Explanati_{on of the T}i_{les Part}i_{al Code 411} Calli_{ng the T}i_{les Part}i_{al Code 412} Wri_{te the Helper Method 413} Generalizing Partials 414

Lambda: _{the Ult}i_{mate 414}

The New Ti_{led Helper Method 415} Conclusi_{on 417}

References 417

Chapter 12 Ajax on Rails 419

Prototype 420

FireBug 421

The Prototype API 421 Top-Level Functions 422

$(i_d[, i_d2..._{]) 422} $$(expr[, expr2..._{]) 423} $A(var) 423

$H(obj) 423

$R(start, end, exclusi_{ve) 423}

Try._{these(func1, func2[, func3}..._{] 423} Class 424

Extensions to JavaScript’s Object Class 425

Object._{clone(object) 425}

Object._extend(desti_nati_{on, source) 425} Object._{keys(obj) and Object}._{values(obj) 425} Object.i_{nspect(param) 426}

Extensions to JavaScript’s Array Class 426

array._{clear() 426} array._{compact() 426}

array._fi_{rst() and array}._{last() 426} array._{flatten() 427}

array.i_{ndexOf(object) 427} array.i_{nspect() 427} array._reverse(i_nli_{ne) 427} array._shi_{ft() 428}

array._wi_{thout(obj1[, obj2,} ..._{]) 428} Extensions to the document Object 428 Extensions to the Event Class 428

Event._{element() 429}

Event._fi_{ndElement(event, tagName) 429} Event.i_sLeftCli_{ck(event) 429}

Event._{observe(element, name, observer, useCapture) and Event}._stopObservi_ng(element, name, observer, useCapture) 429

Event._poi_{nterX(event) and Event}._poi_{nterY(event) 430} Event._{stop(event) 430}

Extensions to JavaScript’s Function Class 430

functi_on._bi_{nd(obj) 430}

functi_on._bi_ndAsEventLi_{stener(obj) 431} Extensions to JavaScript’s Number Class 432

number._{toColorPart() 432} number._{succ() 433} number._ti_{mes() 433}

Extensions to JavaScript’s String class 433

stri_ng._dasheri_{ze() 434}

stri_ng._{escapeHTML() and str}i_ng._{unescapeHTML() 434} stri_ng._evalScri_{pts() and str}i_ng._extractScri_{pts() 434}

stri_ng._{gsub(pattern, replacement) and str}i_ng._{sub(pattern, replacement, count) 434} stri_ng._{scan(pattern,} i_{terator) 434}

stri_ng._stri_{p() 435}

stri_ng._stri_pScri_{pts() and str}i_ng._stri_{pTags() 435} stri_ng._{parseQuery() and str}i_ng._{toQueryParams() 435} stri_ng._{toArray() 435}

stri_ng._{truncate(length, truncat}i_onStri_{ng) 435} stri_ng._{underscore() 436}

The Ajax Object 436

Ajax._acti_{veRequestCount 436} Ajax._{getTransport() 436} Ajax.Responders 437

Ajax._Responders._regi_{ster(responder) 437} Ajax._Responders._unregi_{ster(responder) 437} Enumerable 437

enumerable._each(i_{terator) 438} enumerable._all(i_{terator) 438} enumerable._any(i_{terator) 438}

enumerable._collect(i_{terator) and enumerable}._map(i_{terator) 439} enumerable._detect(i_{terator) and enumerable}._fi_nd(i_{terator) 439} enumerable._eachSli_ce(number[, i_{terator]) 439}

enumerable._fi_ndAll(i_{terator) and enumerable}._select(i_{terator) 439} enumerable._{grep(pattern[,} i_{terator]) 440}

enumerable.i_{nclude(obj) and enumerable}._{member(obj) 440} enumerable.i_{nGroupsOf(num[, f}i_{ller]) 440}

enumerable.i_{nject(accumulator,} i_{terator) 441}

enumerable.i_nvoke(functi_{onName[, arg1, arg2}..._{]) 441}

enumerable._max([i_{terator]) and enumerable}._mi_n([i_{terator]) 441} enumerable._parti_ti_on([i_{terator]) 441}

enumerable._{pluck(propertyName) 442} enumerable._reject(i_{terator) 442} enumerable._sortBy(i_{terator) 442}

enumerable._zi_{p(enum1, enum2[, enum3}..._][, i_{terator]) 443} Hash 443

hash._{keys() and hash}._{values() 443} hash._{merge(another) 443} hash._toQueryStri_{ng() 444} ObjectRange 444

The Prototype Object 445

The PrototypeHelper Module 445

link_to_remote 445 remote_form_for 449 periodically_call_remote 451 observe_field 451

observe_form 453

RJS—Wri_ti_{ng Javascr}i_pt i_{n Ruby 453} RJS Templates 455

<<(javascript) 456 [](id) 457 alert(message) 457

call(function, *arguments, &block) 457 delay(seconds = 1) { ... } 458

draggable(id, options = {}) 458 drop_receiving(id, options = {}) 458 hide(*ids) 458

insert_html(position, id, *options_for_render) 458 literal(code) 459

redirect_to(location) 459 remove(*ids) 459

replace(id, *options_for_render) 460 replace_html(id, *options_for_render) 460 select(pattern) 460

show(*ids) 460

sortable(id, options = {}) 460 toggle(*ids) 461

visual_effect(name, id = nil, options = {}) 461

JSON 461

Sortable 465 Autocompleter 466 In-Place Edi_{tors 467} Conclusi_{on 467} References 468

Chapter 13 Session Management 469

What to Store i_{n the Sess}i_{on 470} The Current User 470

Session Use Guidelines 470

Sessi_{on Opt}i_{ons 471}

Disabling Sessions for Robots 472 Selectively Enabling Sessions 473 Secure Sessions 473

Storage Mechani_{sms 473} ActiveRecord SessionStore 473 PStore (File-Based) 474 DRb Session Storage 475 memcache Session Storage 475 The Controversial CookieStore 476

Ti_mi_{ng Out and Sess}i_{on L}i_{fe Cycle 478} Session Timeout Plugin for Rails 478 Tracking Active Sessions 479 Enhanced Session Security 480 Cleaning Up Old Sessions 481

Cooki_{es 481}

Reading and Writing Cookies 482

Conclusi_{on 483} References 483

Chapter 14 Login and Authentication 485

Acts as Authenti_{cated 486} Installation and Setup 486 The User Model 487

Non-Database Attri_{butes 490} Vali_dati_{ons 492}

The Account Controller 496 Login from Cookie 498 The Current User 499

Loggi_{ng In Dur}i_{ng Test}i_{ng 501} Conclusi_{on 502}

References 502

Chapter 15 XML and ActiveResource 503

The to_xml Method 503

Customizing to_xml Output 505 Associations and to_xml 507 Advanced to_xml 508

Dynamic Runtime Attributes 509 Overriding to_xml 510

Learning from Array’s to_xml Method 510

The XML Bui_{lder 513} Parsi_{ng XML 515}

Turning XML into Hashes 515 XmlSimple 516

Typecasting 518

Acti_{veResource 519} Find 519

Create 522 Update 524 Delete 524 Headers 526 Customizing 527 Hash Forms 528

Conclusi_{on 529}

Chapter 16 ActionMailer 531

Setup 531

Mai_{ler Models 532}

Preparing Outbound Email Messages 533

attachment 534

bcc 534

cc 534 charset 534 content_type 534

from 534

headers 534

i_mpli_ci_{t_parts_order 535}

mai_{ler_name 535} mi_{me_vers}i_{on 535} part 535

reci_pi_{ents 535} sent_on 536 subject 536 template 536

HTML Email Messages 536 Multipart Messages 537

Part Opti_{ons 538}

Impli_ci_{t Mult}i_{part Messages 539} File Attachments 539

Actually Sending an Email 540

Recei_vi_{ng E-Ma}i_{ls 540}

TMail::Mail API Reference 541

attachments 542

body 542

date 542

has_attachments? 542 multi_{part? 542} parts 542 subject 542 to 542

Handling Attachments 543

Confi_gurati_{on 543} Conclusi_{on 544} References 544

Chapter 17 Testing 545

Rails Mocks? 548

Real Mocks and Stubs 549 Integration Tests 550

Dealing with the Confusion 551

Test::_Uni_{t 552} Running Tests 553

Fi_{xtures 554} CSV Fixtures 555

Accessing Fixture Records from Tests 556 Dynamic Fixture Data 556

Using Fixture Data in Development Mode 557 Generating Fixtures from Development Data 558 Fixtures Options 559

Everybody Hates Fixtures 560

Fi_{xtures Make My Test Su}i_{te Slow 560} Fi_{xtures Allow Inval}i_{d Data 560} Mai_ntai_nabi_li_{ty Challenges 561} Fi_{xtures Are Br}i_{ttle 561}

Fixtures Really Aren’t That Bad 562

Asserti_{ons 562} Basic Assertions 562

assert and deny 562 assert_block 563 assert_empty 563

assert_equal and assert_not_equal 563 assert_i_{n_delta and assert_}i_{n_eps}i_{lon 564} assert_i_{nclude 564}

assert_i_{nstance_of 564} assert_ki_{nd_of 564}

assert_match and assert_no_match 564 assert_ni_{l and assert_not_n}i_{l 565} assert_same and assert_not_same 565 assert_rai_{se and assert_noth}i_{ng_ra}i_{sed 565} assert_respond_to 565

flunk 565

One Assertion per Test Method 566

Testi_{ng Models w}i_{th Un}i_{t Tests 568} Model Testing Basics 568

Deciding What to Test 570

Testi_{ng Controllers w}i_{th Funct}i_{onal Tests 570} Structure and Setup 570

Functional Test Methods 571 Common Assertions 572

Assert That Vari_{ables Were Ass}i_{gned Properly for Use by Templates 572} Assert the HTTP Status Code of a Response and Its MIME Content Type 573 Assert the MIME Content Type of a Response (or Other Header Values) 573 Assert Renderi_{ng of a Part}i_{cular Template 574}

Assert Redi_recti_{on to a Spec}i_fi_{ed URL 574} Assert Setti_{ng of Flash Messages 574}

Assert Database Changes Resulti_{ng from Act}i_{ons 575} Assert Vali_di_{ty of a Model 575}

Asserti_{ng V}i_{ew Output 576}

Testi_{ng V}i_{ews w}i_{th Funct}i_{onal Tests 576}

assert_select(selector, [*values, equali_{ty, message, &block]) 577}

assert_select(element, selector, [*values, equali_{ty, message, &block]) 577} Opti_{onal Block Parameter 577}

Selector Reference 578 Equali_{ty Tests 580} Testing RJS Behavior 581

assert_select_rjs(*args, &block) 581 assert_select_rjs(i_{d) 581}

assert_select_rjs(operati_on, i_{d) 582} assert_select_rjs(:i_{nsert, pos}i_ti_on, i_{d) 582} Other Selection Methods 582

assert_select_emai_{l(*args, &block) 582} assert_select_encoded(*args, &block) 582

css_select(selector, *values) and css_select(element, selector, *values) 582

Testing Routing Rules 582

assert_generates(expected_path, opti_{ons, defaults={}, extras = {}, message=n}i_{l) 583} assert_recogni_{zes(expected_opt}i_{ons, path, extras={}, message=n}i_{l) 583}

Rai_{ls Integrat}i_{on Tests 584} Basics 584

The Integration Test API 585

assert_redi_{rected_to(opt}i_{ons = {}, message = n}i_{l) 586} assert_response(type, message = ni_{l) 586}

assert_template(expected = ni_{l, message = n}i_{l) 586} Working with Sessions 586

Rake Tasks Related to Testi_{ng 587} Acceptance Tests 588

Acceptance Test First? 588

Seleni_{um 589} Basics 589

Acti_{ons and Assert}i_{ons 589} Locators 590

Patterns 590

Seleni_{um Reference 590} Getting Started 591

Fi_{rst Test 591} RSelenese 592

Parti_{al Scr}i_{pts 592} Conclusi_{on 593} References 594

Chapter 18 RSpec on Rails 597

Introducti_{on to RSpec 597} Should and Expectations 598 Predicates 599

Custom Expectation Matchers 601 Multiple Examples per Behavior 603 Shared Behaviors 604

RSpec’s Mocks and Stubs 607

Mock Objects 607 Null Objects 608 Stub Objects 608

Running Specs 610

Installing RSpec and the RSpec on Rails Plugin 613

Generators 614 Model Specs 614 Controller Specs 617

Isolati_{on and Integrat}i_{on Modes 619} Speci_fyi_{ng Errors 620}

Speci_fyi_{ng Routes 620} View Specs 621

Assi_gni_{ng Instance Var}i_{ables 622} Stubbi_{ng Helper Methods 623} Helper Specs 623

Scaffolding 623

RSpec Tools 624

Autotest 624 RCov 624

Conclusi_{on 625} References 626

Chapter 19 Extending Rails with Plugins 627

Managi_{ng Plug}i_{ns 628} Reusing Code 628 The Plugin Script 629

scri_pt/plugi_{n l}i_{st 629} scri_pt/plugi_{n sources 630}

scri_pt/plugi_{n source [url [url2 [}..._{]]] 630} scri_pt/plugi_{n unsource [url[url2 [}..._{]]] 631} scri_pt/plugi_{n d}i_{scover [url] 631}

scri_pt/plugi_n i_{nstall [plug}i_{n] 632} scri_pt/plugi_{n remove [plug}i_{n] 633} scri_pt/plugi_{n update [plug}i_{n] 633} Subversion and script/plugin 633

Checki_{ng Out a Plug}i_{n 634} scri_pt/plugi_{n update 634} SVN Externals 635

Locki_{ng Down a Spec}i_fi_{c Vers}i_{on 636} Usi_{ng P}i_{ston 636}

Installation 636

Converting Existing Vendor Libraries 638 Updating 638

Locking and Unlocking Revisions 639 Piston Properties 639

Wri_ti_{ng Your Own Plug}i_{ns 640} The init.rb Hook 640

The lib Directory 642 Extending Rails Classes 643

The README and MIT-LICENSE File 644 The install.rb and uninstall.rb Files 645

Installati_{on 645}

Removal 646

Common Sense Remi_{nder 646} Custom Rake Tasks 647

The Plugin’s Rakefile 648 Testing Plugins 649

Conclusi_{on 649} References 650

Chapter 20 Rails Production Configurations 651

A Bri_{ef H}i_{story of Ra}i_{ls In Product}i_{on 652} Some Basi_{c Prerequ}i_si_{tes 652}

The Stack Checkli_{st 654}

Server and Network Environment 655

Standalone/Dedi_{cated Server or VPS Sl}i_{ce 655} Fresh OS Install 655

Network Access 655

Web Tier 656 Application Tier 656 Database Tier 656 Monitoring 657 Version Control 657

Mongrel Cluster 659 Nginx 659

Subversion 660 MySQL 660 Monit 661 Capistrano 661

Confi_gurati_{ons 661}

Configuring Mongrel Cluster 662 Configuring Nginx 663

ngi_nx._{conf 663} rai_lsway._{conf 664} Configuring Monit 667 Configuring Capistrano 670

Confi_guri_ng i_ni_{t Scr}i_{pts 670} Nginx init Script 670 Mongrel init Script 672 Monit Configuration 673

Deployment and Launch 675

Other Producti_{on Stack Cons}i_derati_{ons 675} Redundancy and Failover 676

Caching 676

Performance and Scalability 676 Security 677

Appli_cati_{on Secur}i_{ty 677} Lock Down Your Ports 678

Maintainability 678

Conclusi_{on 678} References 679

Chapter 21 Capistrano 681

Overvi_{ew of Cap}i_{strano 681} Terminology 682

The Basics 682

What Do I Need to Do to Use Capi_{strano? 682} What Does Capi_{strano Expect? 683}

What Has Capistrano Done and What Hasn’t It? 684

Installation 684

“Capify” Your Rails Application 685 Configuring the Deployment 687

Name Your Appli_cati_{on 687} Reposi_{tory Info 687} Defi_{ne Roles 687} Extra Role Properti_{es 688} A Little Spin, Please… 688

Set Up the Deployment Machine 689

Deployment Di_{rectory Structure 689} Symboli_{c L}i_{nks 690}

Checki_{ng a New Deployment Setup 690} Deploy! 691

Overri_di_{ng Cap}i_{strano Assumpt}i_{ons 691} Using a Remote User Account 691

Customizing the SCM System Used by Capistrano 692

Working without SCM Access from the Deployment Machine 692 What If I Don’t Store database.yml in My SCM Repository? 693

Opti_{on A}: _Versi_{on It Anyway, but w}i_{th a D}i_{fferent Name 693}

Opti_{on B}: _{Store Product}i_{on-Ready database}._yml i_{n the shared/conf}i_{g Folder 694} Opti_{on C}: _{The Best Opt}i_on: _{Autogenerate database}._{yml 694}

What If My Migrations Won’t Run from 0 to 100? 696

Useful Capi_{strano Rec}i_{pes 696} Variables and Their Scope 696 Exercise #1: Staging 698

Exercise #2: Managing Other Services 701

Multi_{server Deployments 702} Transacti_{ons 703}

Proxi_{ed Access to Deployment Mach}i_{nes 705} Conclusi_{on 706}

References 706

Chapter 22 Background Processing 707

scri_{pt/runner 708} Getting Started 708 Usage Notes 709

DRb 710

A Simple DRb Server 711 Using DRb from Rails 711 DRb Considerations 712 Resources 713

BackgrounDRb 713

Getting Started 713 Configuration 714

Understanding BackgrounDRb 715 Using the MiddleMan 715 Caveats 717

BackGrounDRb Considerations 718

Daemons 719

Usage 719

Introducing Threads 720 Daemon Considerations 722

Conclusi_{on 722} References 722

Appendix A ActiveSupport API Reference 723

Appendix B Rails Essentials 805

Rai_ls i_{s more than programm}i_{ng framework for creat}i_{ng web appl}i_cati_ons. _{It’s also a} frame-work for thi_nki_{ng about web appl}i_cati_ons. _{It sh}i_{ps not as a blank slate equally tolerant of} every ki_{nd of express}i_on. _{On the contrary,} i_{t trades that flex}i_bi_li_{ty for the conven}i_{ence of} “what most people need most of the ti_{me to do most th}i_ngs._{” It’s a des}i_{gner stra}i_{ghtjacket that} sets you free from focusi_{ng on the th}i_{ngs that just don't matter and focuses your attent}i_{on on} the stuff that does.

To be able to accept that trade, you need to understand not just how to do somethi_ng i_n Rai_{ls, but also why} i_{t’s done l}i_{ke that}. _{Only by understand}i_{ng the why w}i_{ll you be able to} con-si_{stently work w}i_{th the framework} i_{nstead of aga}i_nst i_t. _{It doesn’t mean that you’ll always have} to agree wi_{th a certa}i_{n cho}i_{ce, but you w}i_{ll need to agree to the overach}i_evi_{ng pr}i_nci_{ple of} conventi_ons. _{You have to learn to relax and let go of your attachment to personal} i_di osyn-crasi_{es when the product}i_vi_{ty rewards are r}i_ght.

Thi_{s book can help you do just that}. _{Not only does} i_{t serve as a gu}i_de i_{n your explorat}i_on of the features i_{n Ra}i_ls, i_{t also g}i_{ves you a w}i_ndow i_{nto the m}i_{nd and soul of Ra}i_ls. _{Why we’ve} chosen to do thi_{ngs the way we do them, why we frown on certa}i_{n w}i_{despread approaches}. It even goes so far as to i_{nclude the d}i_scussi_{ons and stor}i_{es of how we got there—stra}i_{ght from} the communi_{ty part}i_ci_{pants that helped shape them}.

Learni_{ng how to do Hello World} i_{n Ra}i_{ls has always been easy to do on your own, but} getti_{ng to know and apprec}i_{ate the gestalt of Ra}i_{ls, less so}. _{I applaud Ob}i_{e for try}i_{ng to help} you on thi_{s journey}. _Enjoy i_t.

—Davi_{d He}i_nemei_{er Hansson} Creator of Ruby on Rai_ls

xlv

A very heartfelt and speci_{al thank you goes to my ed}i_{tor, Debra W}i_lli_{ams Cauley, for} recog-ni_zi_{ng my potent}i_{al and ever-pat}i_{ently gu}i_di_{ng me through the all of the ups and downs of} getti_{ng th}i_{s book f}i_ni_{shed over the course of a year and a half}. _{She’s also one of the sweetest,} smartest women I know, and I look forward to a long and producti_{ve fr}i_endshi_{p w}i_{th her}. The rest of my team at Addi_{son-Wesley was also phenomenally helpful, pat}i_{ent, and always} encouragi_ng: _{San Dee Ph}i_lli_{ps, Songl}i_{n Q}i_{u, Mand}i_{e Frank, Mar}i_{e McK}i_{nley, and Heather} Fox.

Of course, my fami_{ly bore the brunt of my preoccupat}i_{on w}i_{th work}i_{ng on the book,} especi_{ally dur}i_{ng the last s}i_{x months (once the deadl}i_{ne pressure started gett}i_{ng really} i_ntense). Taylor, Li_{am, and Des}i: _{I love you so much}. _{Thank you for g}i_vi_{ng me the t}i_{me and tranqu}i l-i_{ty to wr}i_te. _{I’ll never be able to thank my longt}i_{me partner (and favor}i_{te Ra}i_{ls developer)}

Desi _{McAdam enough for tak}i_{ng over pract}i_{cally all of my domest}i_{c dut}i_{es dur}i_{ng th}i_{s t}i_me. I also have to thank my dad Marco, for i_nsi_{ghtfully suggest}i_{ng that I propose a whole Ruby} seri_es i_{nstead of just th}i_{s book}.

Wri_ti_{ng a book of th}i_{s scope and magn}i_tude i_{s by no means a solo effort—I owe a} tremendous debt of grati_{tude to my extended team of contr}i_{butors and rev}i_ewers. _Davi_d Black helped ki_{ckstart my early progress by contr}i_buti_{ng mater}i_{al about rout}i_{ng and} con-trollers. _{Fellow ser}i_{es authors James Adam, Trotter Cash}i_{on, and Matt Pellet}i_{er also ch}i_pped i_{n, w}i_{th contr}i_buti_{ons about plug}i_{ns, ActiveRecord, and product}i_{on deployment,} respec-ti_vely. _{Matt Bauer helped me f}i_ni_{sh the Ajax and XML chapters, and Jod}i _{Showers wrote the} Capi_{strano chapter}. _{Pat Maddox rescued me dur}i_{ng a part}i_{cularly bad case of wr}i_{ter’s block} and helped me fi_ni_{sh the RSpec chapter, for wh}i_{ch Dav}i_{d Chel}i_{msky later prov}i_{ded an expert} revi_ew. _{Charles Br}i_{an Qu}i_{nn and Prat}i_{k Na}i_{k prov}i_{ded t}i_{mely adv}i_{ce and contr}i_buti_{ons on} background processi_ng. _Di_{ego Scatagl}i_ni _{also helped w}i_{th rev}i_{ew of some of the later} chap-ters.

Franci_{s Hwang and Sebast}i_{an Delmont prov}i_{ded accurate techn}i_{cal rev}i_{ew, start}i_{ng early} i_{n the l}i_{fe of the book}. _{They were later jo}i_{ned by W}i_{lson B}i_lkovi_{ch and Courtenay Gask}i_ng,

helpi_{ng me to meet f}i_{nal deadl}i_nes. _Wi_lson i_{n part}i_{cular kept me laugh}i_{ng the whole t}i_me wi_{th h}i_{s w}i_{tty comed}i_{c t}i_mi_{ng, and even rewrote the background process}i_{ng chapter to} i ncor-porate hi_{s expert knowledge of the subject}. _{Other valued rev}i_ewers i_{nclude Sam Aaron, Nola} Stowe, and Susan Potter. _{In the last few weeks, my newest fr}i_{end and programm}i_{ng pa}i_{r Jon} “Lark” Larkowski _{has p}i_{cked out a number of rema}i_ni_{ng errors that other rev}i_{ewers somehow} overlooked.

The i_{nfamous Zed Shaw was my roommate dur}i_{ng a s}i_gni_fi_{cant amount of t}i_{me I spent} worki_{ng on the book and was a constant source of} i_nspi_rati_{on and mot}i_vati_on. _{Also a} huuu-uge thank you to my fri_{ends on the #caboose IRC channel for cons}i_{stently prov}i_di_{ng expert} i_nsi_{ghts and op}i_ni_ons. _{Some I’ve already ment}i_{oned—others are (}i_{n no part}i_{cular order)}: _Josh

Susser (hasmanyjosh), Ri_{ck Olson (technoween}i_{e), Ezra Zygmuntov}i_{ch (ezmob}i_{us), Geoffrey} Grosenbach (topfunky), Robby Russel (robbyonrai_{ls), Jeremy Hubert, Dave Fayram (k}i_ri n-dave), Matt Lyon (mattly), Joshua Si_{erles (corp), Dan Peterson (danp), Dave Astels (dastels),} Trevor Squi_{res (protocool), Dav}i_{d Goodlad (dgoodlad), Amy Hoy (er}i_berri_{), Josh Goebel} (Dreamer3), Evan Phoeni_{x (evan), Ryan Dav}i_{s (zensp}i_{der), M}i_{chael Schubert, Cr}i_sti _Balan (evi_{lchelu), Jam}i_{e van Dyke (fearoff}i_{sh), N}i_{c W}i_lli_{ams (drn}i_{ck), Er}i_{c Hodel (drbra}i_{n), James} Cox (i_{majes), Kev}i_{n Clark (kev}i_{nclark), Thomas Fuchs (madrobby), Manfred St}i_enstra (man-fred-s), Pasti_{e Paste Bot (past}i_{e), Evan Henshaw-Plath (rabble), Rob Ors}i_ni _(rorsi_ni_{), Adam} Keys (therealadam), John Athayde (bobori_shi_{), Robert Bousquet, Bryan Helkamp (brynary),} and Chad Fowler. _{I should also ment}i_{on that Dav}i_{d He}i_nemei_{er Hansson (nextangler) h}i m-self was always encouragi_{ng, and even answered a few st}i_{cky quest}i_{ons I had along the way}.

Plenty of former colleagues from ThoughtWorks i_ndi_{rectly helped th}i_{s book happen}. Fi_{rst and foremost, Mart}i_{n Fowler} i_{s not only a role model and} i_nspi_rati_{on—he also helped} me secure the relati_onshi_{p w}i_{th Add}i_{son-Wesley, and offered much personal adv}i_{ce and} sup-port i_{n the early days of the project, when I really had no} i_{dea what I was gett}i_{ng myself} i_nto. ThoughtWorks CEO Roy Si_{ngham recogn}i_{zed the potent}i_{al of Ra}i_ls i_{n early 2005, once I} i_{ntroduced h}i_{m to Dav}i_{d Hansson, and was subsequently steadfast} i_{n h}i_{s support of my Ruby}

evangeli_{sm (}i_ncludi_{ng do}i_{ng qu}i_{te a b}i_{t of} i_{t h}i_{mself around the world)}. _{That was espec}i_ally i_mportant i_{n the early t}i_{mes, when many other respected people at ThoughtWorks thought}

Rai_{ls was noth}i_{ng but hype and wouldn’t last}.