Professional WordPress is the only WordPress book targeted to developers, with advanced content that exploits the full functionality of the most popular CMS in the world. Fully updated to align with WordPress 4.1, this edition has updated examples with all new screenshots, and full exploration of additional tasks made possible by the latest tools and features. You will gain insight into real projects that currently use WordPress as an application framework, as well as the basic usage and functionality of the system from a developer's perspective. The book's key features include detailed information and real-world examples that illustrate the concepts and techniques at work, plus code downloads and examples accessible through the companion website. Written by practicing WordPress developers, the content of this edition focuses on real world application of WordPress concepts that extend beyond the current WordPress version.

WordPress started in 2003 with a single bit of code to enhance the typography of everyday writing, and has grown to be the largest self-hosted website platform in the world. This book helps you use WordPress efficiently, effectively, and professionally, with new ideas and expert perspectives on full system exploitation.

WordPress was born out of a desire for an elegant, well-architected personal publishing system built on PHP and MySQL, and has evolved to be used as a full content management system through thousands of plugins, widgets, and themes.Professional WordPress is the essential developer's guide to this multifunctional system.

Brad Williams is the cofounder of WebDevStudios.com and AppPresser.com, a cohost of the DradCast WordPress podcast, and the coauthor of Professional WordPress Plugin Development.

David Damstra is Vice President of Marketing Services and Creative Director for CU*Answers where his team of developers empowers clients with WordPress.

Hal Stern is an IT executive with a major healthcare company. He is coauthor ofBlueprints for High Availability, also from Wiley.

Wrox Professional guides are planned and written by working programmers to meet the real-world needs of programmers, developers, and IT professionals. Focused and relevant, they address the issues technology professionals face every day. They provide examples, practical solutions, and expert education in new technologies, all designed to help programmers do a better job.

Introduction xxxi

Chapter 1: First Post 1

What is WordPress? 1

Popularity of WordPress 3

Current State 3

Intersecting the Community 4

WordPress and the GPL 5

Content and Conversation 6

WordPress as a Content Management System 6

Creating Conversation 7

Getting Started 7

Hosting Options 8

Do it Yourself Installation 9

Installing WordPress Files 10

Database Configuration 14

Finishing Up 18

FirstTime Administration 18

First Post 20

Summary 21

Chapter 2: Code Overview 23

Downloading 23

Download Locations 23

Available Formats 24

Release Archive 24

Directory and File Structure 25

WordPress Configuration 26

wpconfig.php File 26

Advanced wpconfig.php Options 29

.htaccess 35

The .maintenance File 39

wpcontent User Playground 40

Plugins 40

Themes 41

Uploads and Media Directory 41

Upgrade Directory 41

Custom Directories 42

Summary 42

Chapter 3: Working with Wordpress Locally 43

Benefits of Working Locally 43

Typical Deployment Cycle 44

Why So Much Process? 44

Tools for Component Administration 46

Getting Your Development Stack 46

Adding WordPress to the Local Install 47

Configuration Details 48

Managing the Web Server Document Tree 49

Enabling Debug Information 50

Handling Local and Production Database 53

Creating Virtual Local Server Names 53

Local Theme and Plugin Development 56

Virtual Machines 56

Deploying Local Changes 57

Summary 59

Chapter 4: Tour of the Core 61

Whats in the Core? 61

Using the Core as a Reference 62

Inline Documentation 63

Finding Functions 64

Exploring the Core 66

Deprecated Functions 69

WordPress Codex and Code Reference 70

What is the Codex? 70

Using the Codex 70

Function Reference 72

WordPress APIs 73

Codex Controversy 75

Code Reference 75

Using the Code Reference 75

Code Reference Details 76

Codex Versus Code Reference 77

Dont Hack the Core! 77

Why Not? 77

Alternatives to Hacking the Core 78

Summary 78

Chapter 5: The Loop 79

Understanding the Loop 80

From Query Parameters to SQL 81

Understanding Content in WordPress 82

Putting the Loop in Context 82

Flow of the Loop 83

Template Tags 86

Commonly Used Template Tags 86

Tag Parameters 87

Customizing the Loop 88

Using the WP_Query Object 88

Building a Custom Query 89

Adding Paging to a Loop 92

Using the pre_get_posts Hook 93

Using query_posts( ) 94

Using get_posts( ) 96

Resetting a Query 96

More Than One Loop 98

Advanced Queries 99

Global Variables 102

Post Data 102

Author Data 104

User Data 104

Environmental Data 105

Global Variables or Template Tags? 106

Working Outside the Loop 106

Summary 109

Chapter 6: Data Management 111

Database Schema 111

Table Details 113

WordPress Content Tables 114

WordPress Taxonomy Tables 115

WordPress Database Class 117

Simple Database Queries 117

Complex Database Operations 119

Dealing with Errors 121

Direct Database Manipulation 123

Summary 126

Chapter 7: Custom Post Types, Custom Taxonomies, and Metadata 127

Understanding Data in WordPress 127

What is a Custom Post Type? 128

Register Custom Post Types 128

Setting Post Type Labels 133

Working with Custom Post Types 135

Custom Post Type Template Files 136

Special Post Type Functions 136

WordPress Taxonomy 138

Default Taxonomies 138

Taxonomy Table Structure 139

Understanding Taxonomy Relationships 139

Building Your Own Taxonomies 140

Custom Taxonomy Overview 140

Creating Custom Taxonomies 140

Setting Custom Taxonomy Labels 144

Using Your Custom Taxonomy 145

Metadata 146

What is Metadata? 147

Adding Metadata 147

Updating Metadata 148

Deleting Metadata 148

Retrieving Metadata 149

Community Projects 150

Summary 151

Chapter 8: Plugin Development 153

Plugin Packaging 154

Creating a Plugin File 154

Creating the Plugin Header 154

Plugin License 155

Activating and Deactivating Functions 156

Internationalization 157

Determining Paths 159

Local Paths 160

URL Paths 160

Plugin Security 161

Nonces 161

Data Validation and Sanitization 163

Know Your Hooks: Actions and Filters 166

Actions and Filters 166

Popular Filter Hooks 168

Popular Action Hooks 169

Plugin Settings 171

Saving Plugin Options 171

Array of Options 172

Creating a Menu and Submenus 173

Creating a TopLevel Menu 173

Adding to an Existing Menu 175

Creating an Options Page 176

WordPress Integration 186

Creating a Meta Box 186

Shortcodes 191

Creating a Widget 192

Creating a Dashboard Widget 197

Creating Custom Tables 197

Uninstalling Your Plugin 200

Creating a Plugin Example 201

Publishing to the Plugin Directory 222

Restrictions 222

Submitting Your Plugin 223

Creating a readme.txt File 223

Setting Up SVN 226

Publishing to the Plugin Directory 228

Releasing a New Version 228

Plugin Assets 229

Summary 230

Chapter 9: Theme Development 231

Why Use a Theme? 231

Installing a Theme 232

FTP Installation 233

Theme Installer 233

What is a Theme? 234

Template Files 234

CSS 234

Images and Assets 235

Plugins 235

Creating Your Own Theme 235

Project Themes vs. Child Themes 235

What to Look for in a Starter Theme 236

Creating Your Own Theme: Getting Started 237

Essential File: Style.css 238

Showing Your Content: Index.php 239

Showing Your Content in Different Ways: Index.php 241

Creating Your Own Theme: DRY 241

Header.php 241

Footer.php 243

Sidebar.php 243

Deviations from the Norm: Conditional Tags 244

Creating Your Own Theme: Content Display 245

Customizing Your Homepage: FrontPage.php 246

Show Your Older Posts by Date: Archive.php 249

Showing Only One Category: Category.php 250

Show Posts of a Specific Tag: Tag.php 252

Other Archival Templates 253

How to Show a Single Post: Single.php 253

Display a Page: Page.php 255

Display Post Attachments: Attachment.php 255

Display Custom Post Types 256

Template Hierarchy 256

Creating Your Own Theme: Additional Files 258

Handling 404 Errors: 404.php 258

Author.php 259

Comments.php 260

Adding Functionality to Your Templates: Functions.php 261

Search.php 264

SearchForm.php 265

Other Files 266

Custom Page Templates 266

When to Use Custom Page Templates 267

How to Use Custom Page Templates 268

Stock Twenty Fourteen Page Templates 269

Other Theme Enhancements 269

Menu Management 269

Widget Areas 271

Post Formats 272

Theme Settings 274

Theme Customizer 274

Theme Hierarchy and Child Themes 275

Premium Themes and Other Theme Frameworks 279

Underscores (_s) Theme 280

Bones Theme 280

Carrington Core Theme 280

Genesis Theme 280

Hybrid Core Theme 281

Others Theme 281

Summary 281

Chapter 10: Multisite 283

What is Multisite? 283

Multisite Terminology 284

Differences 284

Advantages of Multisite 285

Enabling Multisite 285

Working in a Network 286

Network Admin 287

Creating and Managing Sites 287

Working with Users and Roles 288

Themes and Plugins 288

Settings 289

Domain Mapping 289

Coding for Multisite 290

Blog ID 290

Common Functions 290

Switching and Restoring Sites 292

Creating a New Site 295

Network Admin Menus 300

Multisite Options 301

Users in a Network 308

Super Admins 310

Network Stats 311

Large Networks 312

Multisite Database Schema 312

MultisiteSpecific Tables 312

SiteSpecific Tables 313

Summary 314

Chapter 11: Migrating to Wordpress 315

Understanding the Process 316

Content Sources 316

Migration Checklist 317

Site Preparation 318

Content Identification 318

Migrating Text Documents 319

Built-In WordPress Import Tools 319

Building a Custom Import Script 321

Media Migration 329

Moving Metadata 330

Moving Authors and Users 330

Theme and Presentation 331

Unique Functionality 331

Cleaning Up 331

Manual Fine-Tuning 332

Import Limitations 332

Updating URLs 332

Redirection 333

Launching 334

WP-CLI 334

What is WP-CLI? 334

Installing WP-CLI 335

Migration Example 335

Summary 337

Chapter 12: Crafting a User Experience 339

User Experience Principles 339

Consistent Navigation 340

Visual Design Elements 342

Making Content Easy to Find 343

Site Load Times 344

Using JavaScript 345

Usability and Usability Testing 346

Structuring Your Information 347

Getting Your Site Found 349

Duplicate Content 351

Trackbacks and Pings 353

How Web Standards Get Your Data Discovered 354

Semantic HTML 354

Valid HTML 356

Microformats 357

HTML5 359

CSS3 361

Searching Your Own Site 361

Weaknesses of the Default Search 362

Alternatives and Plugins to Help 363

Mobile Access and Responsive Web Design 364

Leave it Alone 365

Lightweight Mobile 365

Responsive Design 366

Summary 367

Chapter 13: Securing Wordpress 369

Securing Your WordPress Site 369

Staying UptoDate 370

Hiding WordPress Version Information 371

Never Use the Admin Username 371

Limit Login Attempts 371

Using Good Passwords 371

Changing Your Table Prefix 372

Moving Your Configuration File 372

Moving Your Content Directory 372

Using the Security Key Feature 373

Forcing SSL on Login and Admin 374

Apache Permissions 374

MySQL Credentials 375

Using WordPress Roles 375

Subscriber Role 375

Contributor Role 376

Author Role 376

Editor Role 376

Administrator Role 376

Super Admin Role 377

Role Overview 377

Extending Roles 378

Recommended Security Plugins 378

BulletProof Security 378

WPSecurity Scan 378

WordFence Security 379

Summary 379

Chapter 14: Application Framework 381

What is an Application Framework? 381

WordPress as an Application Framework 382

User Management 382

Template Engine 384

CRUD 384

Caching 386

Friendly URLs 387

External APIs 388

Uploads and Media Management 388

Scheduled Tasks 389

Flexibility 390

Summary 390

Chapter 15: Wordpress in the Real World 391

Is WordPress the Right Tool? 391

When WordPress is Not the Right Tool 393

Defining Content Management 394

Workflow and Delegation 395

User Roles and Delegation 395

Workflow 396

Content Organization 398

Theme and Widget Support 399

Homepages 400

Featured Content Pages 401

Content Hierarchy 403

Interactivity Features 404

Forums 405

Forms 405

ECommerce 405

Scalability 406

Performance Tuning 406

Database Optimizations 408

Regular Database Maintenance 408

Hardware Scaling 409

Statistics Counters 411

AWStats 411

Google Analytics 412

JetPack by WordPress.com 413

Cache Management 413

WordPress System Complexity 414

Web Server Caching and Optimization 416

WordPress Object Caching 417

Transient Caches 418

MySQL Query Cache 420

Load Balancing Your WordPress Site 421

Dealing with Spam 423

Comment Moderation and CAPTCHAs 423

Automating Spam Detection 424

Other Content Management Systems 425

WordPress Integration 425

Where Not to Use WordPress 426

Summary 427

Chapter 16: Wordpress Developer Community 429

Contributing to WordPress 429

Understanding Trac 430

Working on the Core 433

Submitting Plugins and Themes 434

Documentation 434

Sister Projects 435

BuddyPress 435

bbPress 435

Future Projects 435

Resources 436

Codex 436

Handbooks 436

Support Forums 436

WordPress Chat 437

Mailing Lists 438

External Resources 439

WordCamp and Meetups 440

WordPress.TV 440

Theme/Plugin Directories 440

WordPress Ideas 440

WordPress Development Updates 440

Make WordPress.org 441

WordPress Podcasts 441

WordPress News Sites 442

Summary 443

Index 445