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![@Josh412
Creating Filters: Before
function prefix_get_form( $id ){
return get_option( $id, [] );
}](https://image.slidesharecdn.com/introductiontoplugindevelopment-160910122536/75/Introduction-to-plugin-development-37-2048.jpg)
![@Josh412
Creating Filters: After
function prefix_get_form( $id ){
$form = get_option( $id, [] );
$form = apply_filters( 'prefix_get_form', $form, $id );
return $form;
}](https://image.slidesharecdn.com/introductiontoplugindevelopment-160910122536/75/Introduction-to-plugin-development-38-2048.jpg)
![@Josh412
Creating Filters: Before
function prefix_get_form( $id ){
return get_option( $id, [] );
}](https://crownmelresort.com/image.slidesharecdn.com/introductiontoplugindevelopment-160910122536/75/Introduction-to-plugin-development-37-2048.jpg)
![@Josh412
Creating Filters: After
function prefix_get_form( $id ){
$form = get_option( $id, [] );
$form = apply_filters( 'prefix_get_form', $form, $id );
return $form;
}](https://crownmelresort.com/image.slidesharecdn.com/introductiontoplugindevelopment-160910122536/75/Introduction-to-plugin-development-38-2048.jpg)
Uploaded byCaldera Labs
Introduction to plugin development
This document provides an introduction to plugin development in WordPress from Josh Pollock of CalderaLabs. It discusses what plugins are, why developers should create them, how to structure them, and best practices for the plugin API. Key topics covered include using hooks and filters, plugin organization, and prioritizing security, reuse, and good coding standards.
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Introduction to plugin development
- 1. @Josh412 Introduction To Plugin Development JoshPollock | CalderaLabs.org
- 2. @Josh412 CalderaLabs.org Hi I'm Josh LeadDeveloper: CalderaWP I make WordPress plugins I teach about WordPress I wrote a book about the WordPress REST API I am core contributor to WordPress I am a member of The WPCrowd
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- 4. @Josh412 CalderaLabs.org Turn Code Off Easytroubleshooting!
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- 6. @Josh412 CalderaLabs.org Share Code Distribute onGithub or WordPress.org
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- 9. @Josh412 How To MakeA Plugin Step 1: Add a new directory to the plugins directory (optional). Step 2: Add a file in that directory or the plugins directory with a valid plugin header. Step 3: Write code (optional).
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- 11. @Josh412 CalderaLabs.org Plugins vs Themes OrCan’t I Put That In functions.php ??
- 12. @Josh412 CalderaLabs.org It’s a freesoftware, you can do whatever you want, but...
- 13. @Josh412 Plugins vs Themes:Best Practices Themes should be use to present a unique design Everything else should be in a plugin.
- 14. @Josh412 Should This CodeGo In functions.php ? Is the answer to any of these questions no: Do I ever want to reuse this code apart from this theme? Will I miss this code when I switch themes? Switch for troubleshooting. Switch for new look. Can I use this code for other purposes?
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- 16. @Josh412 Plugin Header: GoesIn Main File <?php /* Plugin Name: My Plugin */
- 17. @Josh412 Main File: TheFile With A Plugin Header Plugin Header License/ Copyright/ Contact Info Check Dependencies & Requirements Load Plugin Start Plugin
- 18. @Josh412 Directory Structure There AreNo Rules You Should Have Rules I like PSR-4 :)
- 19. @Josh412 Naming Things There AreNo Rules You Should Have Rules I like to document naming conventions:)
- 20. @Josh412 Naming Things: naming-conventions.txt PluginName -- Text domain -- Function prefix -- Class prefix -- Root namespace -- Hook Prefix --
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- 22. @Josh412 CalderaLabs.org Hooks Are Events WhenWe Get Here: Do This
- 23. @Josh412 CalderaLabs.org Don’t Hack Core Modifying Core/Plugins / Themes Is A Bad Idea You Will Lose Your Changes On Update
- 24. @Josh412 CalderaLabs.org Hooks Let YouChange WordPress/ Plugins/ Themes Without Editing Files
- 25. @Josh412 CalderaLabs.org Filters Change A Variable’sValue At A Specific Time
- 26. @Josh412 CalderaLabs.org Actions Do Something At ASpecific Time
- 27. @Josh412 Actions Do something Don’t returnvalues* Actions Vs Filters Filters Change something Must return a value*
- 28. @Josh412 CalderaLabs.org Use Hooks InYour Plugins To Add New Functionality
- 29. @Josh412 CalderaLabs.org Add Hooks InYour Plugins To Make Your Plugin Extensible
- 30. @Josh412 do_action() Triggers the action UsingActions add_action() Hooks a function to an action
- 31. @Josh412 Using Actions: PrintTracking Pixel function my_prefix_pixel() { echo '<img src="https://adnetwork.com/pixel.gif" width="0" height="0">'; } add_action( 'wp_footer', 'my_prefix_pixel' );
- 32. @Josh412 Using Actions: ModifyWP_Query function search_filter($query) { if ( !is_admin() && $query->is_main_query() ) { if ($query->is_search) { $query->set('post_type', array( 'post', 'movie' ) ); } } } add_action('pre_get_posts','search_filter');
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- 34. @Josh412 apply_filters() Creates the filter UsingFilters add_filter() Hooks a function to a filter
- 35. @Josh412 Using Filters: AddTo Content add_filter( 'the_content', 'slug_callback' ); function slug_callback( $content ){ return $content . '<p class="cta">Hey Sign Up for My Thing!</p>'; }
- 36. @Josh412 Using Filters: AddTo Content add_filter( 'the_content', function( $content ){ return $content . '<p class="cta">Hey Sign Up for My Thing!</p>'; });
- 37. @Josh412 Creating Filters: Before functionprefix_get_form( $id ){ return get_option( $id, [] ); }
- 38. @Josh412 Creating Filters: After functionprefix_get_form( $id ){ $form = get_option( $id, [] ); $form = apply_filters( 'prefix_get_form', $form, $id ); return $form; }
- 39. @Josh412 Hook Priority add_filter( 'name','callback',2 ); add_filter( 'name', 'callback_two', 55 );
- 40. @Josh412 Hook Arguments $form =apply_filters( 'prefix_get_form', $form, $id ); add_filter( 'prefix_get_form', function( $form, $id ){ if( 'CF1234567' == $id ){ // do something to $form } return $form; }, 10, 2 );
- 41. @Josh412 CalderaLabs.org Making Plugins Josh’s RulesFor Plugin Development
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- 44. @Josh412 HTTP requests That functionswill be used how you intended them Data returned from the database Yourself Some Things Not To Trust
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- 48. @Josh412 Single Responsibility Principle Functionsshould do one thing. Do Not Repeat Yourself (DRY) Functions, not copypaste Making Code Reusable
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- 50. @Josh412 CalderaLabs.org Using Classes Doesn’t MakeYour Code Object-Oriented
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