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![Nonce SecurityNumber used onceMake sure requests coming from authenticated user with unique code$nonce= wp_create_nonce ('my-nonce');wp_nonce_field("qday","qnonce") is the same as:<input type=“text” name=“qnonce” value=“<?=$nonce?>”>Test:Code: if(wp_verify_nonce($_POST["qnonce"], "qday") )](https://image.slidesharecdn.com/phpwordpresscustomization-wordcamp-110304215732-phpapp02/75/Introduction-to-Plugin-Programming-WordCamp-Miami-2011-20-2048.jpg)
![DB Programming PitfallsForgetting to declare $wpdb as globalUse ARRAY_A parameter to get associative array from $wpdb->get_results or $wpdb->get_row if you want results to be accessible as $row["field_name"]Default is object format $row->field_nameUse $wpdb->show_errors() to debug SQLReturn value from $wpdb->query is false on error, or number of rows affected (could be 0)Test for error: if($return_value == false) echo ‘error’;](https://image.slidesharecdn.com/phpwordpresscustomization-wordcamp-110304215732-phpapp02/75/Introduction-to-Plugin-Programming-WordCamp-Miami-2011-28-2048.jpg)
![ShortcodesPlaceholder codes site editors can include in pages and postsStandard:[embed] http://www.youtube.com/watch?v=nTDNLUzjkpg[/embed]Custom:[demotag title="Date" date="r"] Date in RFC822 Format [/demotag]](https://image.slidesharecdn.com/phpwordpresscustomization-wordcamp-110304215732-phpapp02/75/Introduction-to-Plugin-Programming-WordCamp-Miami-2011-30-2048.jpg)
Uploaded byDavid Carr
Introduction to Plugin Programming, WordCamp Miami 2011
David F. Carr's presentation at WordCamp Miami 2011 discusses customizing WordPress through plugins and themes, explaining the advantages of using WordPress for web development, including its strong community, SEO friendliness, and rich resources. He covers the anatomy of themes, the WordPress file hierarchy, and how to leverage hooks and filters to alter site behavior and content management. The presentation also highlights the importance of security and database management in WordPress development, along with practical coding examples and resources for further learning.
Introduction to Plugin Programming, WordCamp Miami 2011
- 1. PHP WordPressCustomizationWordCamp Miami2011Take the Good Parts, Then Bend It To Your WillBy David F. Carrdavid@carrcommunications.com
- 2. Self IntroductionFreelance writer,editor, and web consultantWrite for Forbes.com on cloud computing, technology for small to midsize businessesTechnology Editor for WebWeek / Internet World Magazine in1990s, Baseline Magazine 2001-2008Webmaster for small businesses, community organizations, political campaignsWordPress replaced a lot of custom hacksWill mostly be talking about plugins to modify the behavior of the system
- 3. OverviewWhy start withWordPress?A Plugin Is Just PHP, a Theme Is PHP/CSSJavaScript / AJAX, tooFiles, system load, and The LoopHooking into Filters and ActionsCustomizing the admin screensCustomizing the front endCreating a custom post typeWhere to learn more
- 4. When a PluginMakes You Popular
- 5. Why Start WithWordPress?Faster than starting from a clean sheet of paper (blank screen of code)Content management for blogs, web pagesSEO friendlyAvailability of vast array of free themes and plugins, plus commercial optionsLots of tutorial materialStrong developer community
- 6. A Plugin IsJust PHP
- 7. Anatomy of aThemeThemes have a similar header in style.css.Theme loads index.php (or page.php, single.php, archive.php) to execute “the loop.” Each also loads header.php, footer.php, and usually sidebar.php
- 8.
- 9. Globals and LookupFunctionssite_url()admin_url()content_url() or WP_CONTENT_URLplugins_url() or WP_PLUGIN_URLincludes_url()home_url()WP_PLUGIN_DIRWP_CONTENT_DIRABSPATH – directory including trailing /None of the rest include trailing /So $url = plugins_url() . /demo/report.php
- 10. More Globals, ConditionalFunctionsNeed to use global keyword at top of function to accessglobal $wpdb – database objectglobal $post$post-ID, $post->post_typeglobal $current_user$current_user->first_nameConditional functionsis_user_logged_in()is_single() or is_single(10)is_page or is_page(10) or is_page('about_us')is_admin() – is this an admin page?
- 11. WordPress File HierarchyThewp-content directory has subdirectories for plugins and themesThe index.php in web root loads the system, loads activatedplugins and themesPlugins: functionalityThemes: look and feelfunctions.php – theme-specific behavior
- 12. Hooking Into WordPressCoreWordPress API built around 2 kinds of hooks:Filter hooks – intercept some bit of content, modify it, return it. Mostly UI but also some back end filters.A filter on ‘the content’ modifies the content of a post.A filter on ‘posts_orderby’ modifies the ORDER BY clause in the SQL for retrieving posts.Action hooks – triggered by an event in WordPress initialization or loading of template files.The ‘init’ action comes after database is loaded but before page display starts. Can be used to act on a $_POST, then redirect.The ‘wp_header’ and ‘wp_footer’ actions called from header.php and footer.php output custom contentOther actions specific to admin screens, like ‘admin_menu’
- 13. Key Actions PublicPagemuplugins_loadedplugins_loadedsetup_themeload_textdomainset_current_userinitwp_loadedparse_requestsend_headersparse_querypre_get_postsposts_selectionwptemplate_redirectwp_headwp_enqueue_scriptswp_print_styleswp_print_scriptsloop_startthe_postloop_endget_sidebarwp_footerwp_print_footer_scriptsshutdown
- 14. Sample Filterswp_title (pagetitle)the_title (post title)the_contentthe_content_feedthe_excerptthe_excerpt_rssthe_categorythe_tagsthe_timethe_datethe_weekdaycomment_textcomment_save_prethe_editor_contentwp_list_pagessave_postwp_insert_post_datalogin_redirectcron_schedulesmce_css (rich text editor)posts_requestposts_joinposts_orderbyposts_where
- 15. Modifying Admin ScreensTheDefault Dashboard
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- 17.
- 18. Function to outputmenu page
- 19. Admin Data EntryPage
- 20. Nonce SecurityNumber usedonceMake sure requests coming from authenticated user with unique code$nonce= wp_create_nonce ('my-nonce');wp_nonce_field("qday","qnonce") is the same as:<input type=“text” name=“qnonce” value=“<?=$nonce?>”>Test:Code: if(wp_verify_nonce($_POST["qnonce"], "qday") )
- 21. Catching $_POST atinit / admin-init
- 22. Process, Then RedirectSeparateUI from server processingHelps avoid double-submit issuesRedirect with different parameters for success / failureExit after redirectSimilar pattern can be used for AJAX (echo json, then exit)
- 23. Wrapper Functions ForWP DatabaseCreate a post with code using wp_insert_postRetrieve and change settings using get_option and update_option
- 24.
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- 26. Database Programming withWordPressGlobal $wpdb data access objectGet results with $wpdb->get_resultsGet row with $wpdb->get_rowFormat/quote SQL with $wpdb->prepare
- 27. Insert / Update RemembersecurityCheck nonceFilter valuesCompensate for “magic quotes” with$postdata = array_map( 'stripslashes_deep', $_POST );Use $wpdb->prepare to quote properlyExecute insert / update with $wpdb->query($sql)
- 28. DB Programming PitfallsForgettingto declare $wpdb as globalUse ARRAY_A parameter to get associative array from $wpdb->get_results or $wpdb->get_row if you want results to be accessible as $row["field_name"]Default is object format $row->field_nameUse $wpdb->show_errors() to debug SQLReturn value from $wpdb->query is false on error, or number of rows affected (could be 0)Test for error: if($return_value == false) echo ‘error’;
- 29. Allow For AlternateTable NamesDefault table names like wp_posts can have alternate prefixes, so use $wpdb->posts insteadCustom table $wpdb->prefix . "rsvpmaker"
- 30. ShortcodesPlaceholder codes siteeditors can include in pages and postsStandard:[embed] http://www.youtube.com/watch?v=nTDNLUzjkpg[/embed]Custom:[demotag title="Date" date="r"] Date in RFC822 Format [/demotag]
- 31. Contact Form ExampleUsea shortcode to display formProcess $_POST on ‘init’ then redirectUse JavaScript jQuery library to enhance
- 32. Enqueue Bundled /Custom JavaScriptLoad scripts in right order with wp_enqueue_scriptRegister custom scripts, dependencies with wp_register_script
- 33. jQuery and Friends“NoConflict” mode so start with jQuery(document).ready(function($)Warning: Textbook jQuery examples usually start with this shortcut:$(document).ready(function()
- 34. Live Example -RSVPMaker
- 35. Creating a CustomPost TypeAdd a content type that can use common editing controls but be organized separately
- 36. Editing Screen WithCustom OptionsStandard formatting / uploading controlsCustom panels: add_meta_boxProcess $_POST on save_post actionSave custom data: update_post_meta
- 37. Custom Display forCustom Post TypeFilter ‘the_content’, check post type, look up and format dates for events, display form if is_single() otherwise show RSVP Now! button
- 38. SummaryWordPress provides afoundation / frameworkCreate / customize themes to change look and feelDownload or create your own plugins to alter WordPress system behaviorFilters hooks alter content, return resultsAction hooks triggered by initialization stages, function calls in theme templates, administration screen accessCreate your own administration reports / data entry screens.Use wrapper functions and $wpdb global to update DBUse shortcodes, filters, output functions for JavaScript and CSS to enhance public website
- 39. Follow UpEmail: david@carrcommunications.comRecommendedbook:WordPressPlugin Development – Beginner’s Guide by Vladimir PrelovacPresentation/Code/Links:www.carrcommunications.com/wordcamp/www.carrcommunications.com/wordpress-plugins/Developer documentation codex.wordpress.orgForums wordpress.org/support/Mailing lists (wp-hackers etc.) lists.automattic.com