Plugin Development @ WordCamp Norway 2014
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This document summarizes a presentation on plugin development for WordPress. The presentation covers topics like plugin architecture, coding standards, documentation, testing, security, internationalization, and more. It emphasizes best practices for WordPress plugin development like using the WordPress API, hooks and filters, object-oriented programming, documentation, testing, and security practices like sanitizing data.
![JavaScript Hooks
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JavaScript events
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$('body').bind(’event’, function(event, the_value) { });
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$('body').trigger(’event', [ value ]);](https://image.slidesharecdn.com/wordcamp-norway-2014-140125071934-phpapp02/85/Plugin-Development-WordCamp-Norway-2014-16-320.jpg)
![Naming Conventions
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function some_name( $some_variable ) { [...] }
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class Walker_Category extends Walker { [...] }
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class WP_HTTP { [...] }
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my-plugin-name.php
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class-my-class.php](https://image.slidesharecdn.com/wordcamp-norway-2014-140125071934-phpapp02/85/Plugin-Development-WordCamp-Norway-2014-20-320.jpg)
![PHP standards
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if ( contidion )
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my_function( $parameter )
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$array[‘index’]
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$array[ $index ]
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WordPress coding standards configuration for PhpStorm by Rarst:
https://gist.github.com/Rarst/1370155](https://image.slidesharecdn.com/wordcamp-norway-2014-140125071934-phpapp02/85/Plugin-Development-WordCamp-Norway-2014-22-320.jpg)
![Prefixing
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WordPress : PHP version 5.2.4 or greater
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Namespaces : 5.3.0 or greater
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Prefix your classes
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class WPSEO_Admin { [...] }](https://image.slidesharecdn.com/wordcamp-norway-2014-140125071934-phpapp02/85/Plugin-Development-WordCamp-Norway-2014-68-320.jpg)
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Plugin Development @ WordCamp Norway 2014
- 2. Barry Kooij • Senior Web Developer @ Yoast • WordPress SEO (Premium),What The File, Sub Posts • Contributor EDD, EDD extensions • Moderator WPNL forum • Twitter: @cageNL
- 5. Hold up!
- 6. There more to a good plugin than good code!
- 7. Wait, what?
- 8. My Setup
- 9. My Setup • MacBook Pro Retina • PhpStorm • GIT -> GitHub • Vagrant w/ Varying Vagrant Vagrants (VVV) -10up
- 10. Debugging
- 11. Debugging define( 'WP_DEBUG', true ); if ( WP_DEBUG ) { define( 'SCRIPT_DEBUG', true ); define( 'WP_DEBUG_LOG', true ); define( 'WP_DEBUG_DISPLAY', true ); @ini_set( 'display_errors', 1 ); } display_errors = On; error_reporting = E_ALL | E_STRICT; Xdebug
- 12. WordPress Core
- 13. Open source • WordPress is open source • No really, literally OPEN SOURCE • The code and documentation is all in your project • Try command clicking a function
- 14. API • Dashboard Widgets API • Rewrite API • Database API • Settings API • HTTP API • Shortcode API • File Header API • Theme Modification API • Filesystem API • Theme Customization API • Metadata API • Transients API • Options API • Widgets API • Plugin API • XML-RPC WordPress API • Quicktags API • Image Manipulation API
- 15. Hooks & Filters • add_action( ‘hook_name’, ‘my_hook_callback’ ); • do_action( ‘hook_name’ ); ! • add_filter( ‘filter_name’, ‘my_filter_callback’ ); • $new_value = apply_filters( ‘filter_name’, $old_value );
- 16. JavaScript Hooks • JavaScript events • $('body').bind(’event’, function(event, the_value) { }); • $('body').trigger(’event', [ value ]);
- 18. Backwards Compatibility • Don’t remove code, deprecate it • Don’t change unit tests but add new unit tests to test your update
- 19. Code Standards
- 20. Naming Conventions • function some_name( $some_variable ) { [...] } • class Walker_Category extends Walker { [...] } • class WP_HTTP { [...] } • my-plugin-name.php • class-my-class.php
- 21. Databases • Always use the WP API! • $wpdb->prepare( "SELECT * FROM {$wpdb->posts} WHERE `ID` = %d", $id );
- 22. PHP standards • if ( contidion ) • my_function( $parameter ) • $array[‘index’] • $array[ $index ] • WordPress coding standards configuration for PhpStorm by Rarst: https://gist.github.com/Rarst/1370155
- 23. Yoda Conditions if ( true === $the_force ) { $victorious = you_will( $be ); } ! A little bizarre, it is, to read. Get used to it, you will.
- 24. Code Templates
- 25. Code Templates • Predefined code with parameters • https://gist.github.com/barrykooij/7632945
- 26. The project
- 27. Open source your code!
- 28. What is someone ‘steals’ my code?!
- 29. What is someone tells me it’s poorly written?!
- 30. Open source your project • Yes, it’s definitely scary. • It’s what drives our community • It’s the future, not only of code
- 31. Versioning • Work with major, minor and bugfix release (x.y.z)
- 32. Changelog • Always keep a public change log • Give props to other people
- 34. WordPress repository • Use a header image • Have clear description what your plugin does • Non consumers rate by downloads combined with rating
- 36. Ask for ratings • Users don’t mind rating your plugin • Don’t ask right away, let the user use your product first • Make it a optional, and make this very clear!
- 37. Performance
- 38. Object Orientated Programming • Write OOP code, period. • Don’t know how? Learn it!
- 39. Conditional loading of code • Don’t load every class on every page load • Don’t initialise every class on every page load • Split frontend and backend classes - is_admin() • Use an autoloader
- 40. Documentation
- 41. Code documentation • Write code documentation, people will love you for it! • Write inline documentation directly after the function declaration • • • You won’t ‘forget’ writing it afterwards You’re making yourself rethink what you function should do All good IDE’s will use the inline documentation for autocompletion
- 42. Inline documentation • Explain what you’re doing • Explain why you’re doing it
- 43. Security
- 44. Sanitizing data • Checking if data is of an expected structure (e.g. email) • • is_email Reformatting data so it will be of expected structure (e.g. title) • sanitize_title http://codex.wordpress.org/Data_Validation#Input_Validation
- 45. Escaping data • Prevent XSS attacks, escape your data! • esc_url • esc_html
- 46. Capabilities • Is the user allowed to do this? ! // Check capabilities if ( ! current_user_can( 'manage_options' ) ) { wp_die( __( 'Cheatin’ uh?' ) ); }
- 47. Direct file access • Don’t allow direct access to files • Place this at the top of your files: if ( ! defined( 'ABSPATH' ) ) { header( 'HTTP/1.0 403 Forbidden' ); die; }
- 48. Asynchronous Javascript And XML
- 49. AJAX
- 50. AJAX allows you to run server side scripts asynchronous
- 51. WordPress made AJAX really simple!
- 52. Register the AJAX action • Tell WordPress your plugin is accepting AJAX requests • add_action( ‘wp_ajax_my_ajax_action’, array( $this, ’callback’ ) ); • add_action( ‘wp_ajax_nopriv_my_ajax_action’, array( $this, ’callback’ ) );
- 53. Use jQuery to do the POST jQuery.post( ajaxurl, { action : 'my_ajax_action', ajax_nonce : jQuery(‘.wpseo_redirects_ajax_nonce').val(), my_var : my_val }, function (response) { // Do something } );
- 55. Make your plugin translatable • load_plugin_textdomain( ‘my-textdomain', false, dirname( plugin_basename( __FILE__ ) ) . '/languages/' ); ! • __( ‘My String’, ‘my-textdomain’ ); • _e( ‘My String’, ‘my-textdomain’ );
- 56. Generate a .pot file
- 60. Unit Tests
- 61. An automated piece of code that invokes your application code to check a single assumption.
- 62. Unit Test example function test_get_single_role_by_user_query() { // Arrange $this->factory->user->create_many( 2, array( 'role' => 'subscriber' ) ); // Act $wp_user_search = new WP_User_Query( array( 'role' => 'subscriber' ) ); $users = $wp_user_search->get_results(); } // Assert $this->assertEquals( 2, count( $users ) );
- 63. Code
- 64. Loading your plugin // Create object - Plugin init add_action( 'plugins_loaded', create_function( '', 'new MyPlugin();' ) );
- 65. Plugin DIR & FILE if ( ! defined( ’X_PLUGIN_DIR' ) ) { define( 'X_PLUGIN_DIR’, plugin_dir_path( __FILE__ ) ); } if ( ! defined( ’X_PLUGIN_FILE' ) ) { define( ’X_PLUGIN_FILE', __FILE__ ); }
- 67. But, you can’t use them.
- 68. Prefixing • WordPress : PHP version 5.2.4 or greater • Namespaces : 5.3.0 or greater • Prefix your classes • class WPSEO_Admin { [...] }
- 69. Test your plugin on PHP 5.2
- 70. Thank you. ! Find me on Twitter: @CageNL