Williams Brad - Wordpress plugin Development

1. Chapter 3
2. Chapter 12

1. Chapter 1
2. Chapter 3
3. Chapter 4
4. Chapter 7
5. Chapter 8
6. Chapter 9
7. Chapter 10
8. Chapter 11
9. Chapter 12
10. Chapter 13
11. Chapter 14
12. Chapter 15
13. Chapter 16

Second Edition

Brad Williams

Justin Tadlock

John James Jacoby

Copyright 2020 by John Wiley & Sons, Inc., Indianapolis, Indiana

Published simultaneously in Canada and the United Kingdom

ISBN: 978-1-119-66694-3
ISBN: 978-1-119-66697-4 (ebk)
ISBN: 978-1-119-66693-6 (ebk)

No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 646-8600. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008, or online at www.wiley.com/go/permissions.

Limit of Liability/Disclaimer of Warranty: The publisher and the author make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation warranties of fitness for a particular purpose. No warranty may be created or extended by sales or promotional materials. The advice and strategies contained herein may not be suitable for every situation. This work is sold with the understanding that the publisher is not engaged in rendering legal, accounting, or other professional services. If professional assistance is required, the services of a competent professional person should be sought. Neither the publisher nor the author shall be liable for damages arising herefrom. The fact that an organization or Web site is referred to in this work as a citation and/or a potential source of further information does not mean that the author or the publisher endorses the information the organization or Web site may provide or recommendations it may make. Further, readers should be aware that Internet Web sites listed in this work may have changed or disappeared between when this work was written and when it is read.

For general information on our other products and services please contact our Customer Care Department within the United States at (877) 762-2974, outside the United States at (317) 572-3993 or fax (317) 572-4002.

Wiley publishes in a variety of print and electronic formats and by print-on-demand. Some material included with standard print versions of this book may not be included in e-books or in print-on-demand. If this book refers to media such as a CD or DVD that is not included in the version you purchased, you may download this material at booksupport.wiley.com. For more information about Wiley products, visit www.wiley.com.

Library of Congress Control Number: 2020935186

Trademarks: Wiley, the Wiley logo, Wrox, the Wrox logo, Programmer to Programmer, and related trade dress are trademarks or registered trademarks of John Wiley & Sons, Inc. and/or its affiliates, in the United States and other countries, and may not be used without written permission. WordPress is a registered trademark of WordPress Foundation Corporation. All other trademarks are the property of their respective owners. John Wiley & Sons, Inc., is not associated with any product or vendor mentioned in this book.

To my son, Lucas Royce Williams, for reminding me to always stay curious.

BRAD WILLIAMS

To my grandmother, Angeline Granny Frazier, for keeping me fed with homecooked meals during the writing process.

JUSTIN TADLOCK

To my wife, Keri, for her boundless support and patience. To Brad and Justin for inviting me along. To everyone who has helped me along the way. To Penny and Paul.

JOHN JAMES JACOBY

BRAD WILLIAMSis the CEO and cofounder of WebDevStudios, one of the oldest and most respected WordPress agencies in the world. He is a coauthor of the Professional WordPress book series. Brad is the coorganizer of WordCamp Philly 20102015 and the Philadelphia WordPress Meetup. He was also a coorganizer for the Inaugural WordCamp US in 2015 and again in 2016. Brad has been developing websites for more than 20 years, including the last 10 where he has focused on open source technologies like WordPress.

JUSTIN TADLOCKbegan using WordPress in 2005 as a platform to share his writing. He fell in love with design and development, which prompted him to launch his first business in 2008. He ran Theme Hybrid, one of the earliest theme and plugin shops, for more than a decade. During this time, he created more than 70 plugins and themes for public release and many more for custom jobs. He also spent time as an administrator for the official WordPress theme review team. His latest adventure is writing for WP Tavern. Outside WordPress, Justin likes to collect films and makes time to read every day. You can follow his personal journey at justintadlock.com.

JOHN JAMES JACOBYis a software developer who started writing code at 13 years old, late at night, in a dark bedroom, on a shabby computer that his dad spent way too much money on. He found bbPress first, then BuddyPress, and finally WordPressMU, which is now simply known as WordPress Multisite. He's been the project lead for BuddyPress and bbPress since 2008; is a member of the WordPress.org Administration and Security teams and a component maintainer for Multisite, Options, and User Roles; and has contributed to more than 50 free plugins on WordPress.org that are active on nearly 15 million websites. When he's not coding, he likes spending time at home with his family, paddle boarding, and grumping around his local community. You can find him on the web at jjj.blog.

TO MY SON, LUCAS,for being my daily inspiration and best friend. To the love of my life, April, thank you for your endless support, friendship, and continuing to put up with my nerdy ways. To Lisa SabinWilson, your partnership and friendship have helped me grow not only as a business leader but as a person. To Justin and John, two amazing coauthors, your knowledge of WordPress is unmatched, and this book wouldn't have been what it is without you both. Thank you to the entire WordPress community for your support, friendships, motivation, and guidance over the years.

BRAD WILLIAMS

To the WordPress community, you've been my online family for 15 years. You've given me an opportunity to have a career doing something I'm passionate about. It's been a wild ride thus far. To the thousands of users who've installed my plugins and themes, thank you for sticking with me all these years. To my parents, thank you for allowing me to dream big. To my family and friends, I'll try to find better dinner conversation topics than WordPress in the future. Thanks for lending an ear on a topic you know nothing about other than it being my job. To my cats, each day is a mixed bag of frustration and joy, but it's never boring. Thanks for mostly staying off my keyboard while I'm writing.