How to start developing your own ExpressionEngine addons

How to start developing your own addons http://newism.com.au / @newism

Leevi Graham • Developed 25+ addons over 2 years • First Addon: LG Better Meta - July 2007 • Technical Director at Newism • Devot:ee ExpressionEngine developer of the year • leevigraham

Introduction • Addon primer • Finding addons + development resources • Developing addons

Plugins

Strengths • Simple to build • Front end tag parsing • Custom ﬁeld text formatting • Single PHP ﬁle

Strengths Weaknesses • Simple to build • No control panel adminstration • Front end tag parsing • Custom field text • No built in settings formatting • No language file • Single PHP file • No form submission processing

Image Sizer • Developed by: Lumis {exp:imgsizer:size • Resizes images - single image='foo.jpg' width='200' tag alt='My Title' • Caches output id='img_5334' class='entry_img' • http://www.lumis.com/page/ } imgsizer/

NSM Referrer Alert • Developer: Newism {exp:nsm_referrer_alert_pl} {if no_results}<p>No referrer found</p>{/if} <ul> • Outputs refer data in a <li>ref_scheme: {ref_scheme}</li> <li>ref_host: {ref_host}</li> tag pair <li>ref_port: {ref_port}</li> <li>ref_user: {ref_user}</li> <li>ref_pass: {ref_pass}</li> • <li>ref_path: {ref_path}</li> Check the number of <li>ref_query: {ref_query}</li> references <li>ref_fragment: {ref_fragment}</li> <li>ref_search_engine: {ref_search_engine}</li> <li>ref_search_terms: {ref_search_terms}</li> <li>ref_visit_count: {ref_visit_count}</li> • http://newism.github.com/ </ul> nsm.referrer_alert.ee_addon/ {/exp:nsm_referrer_alert_pl}

Modules

Strengths • Front end tag parsing • Control panel administration • Easy upgrade from plugin • Process form submissions

Strengths Weaknesses • Front end tag parsing • Multiple module and language ﬁles • Control panel administration • Multiple install locations • Easy upgrade from plugin • No built in settings • Process form submissions

Freeform • Developed by: Solspace • Custom forms • Record submissions in DB • Email notiﬁcations • http://www.solspace.com/software/ detail/freeform/

LG Quarantine • Developed by: Newism • Flag comments & entries as inappropriate • Quarantine comments / entries after n ﬂags • Control Panel reporting • http://leevigraham.com/cms- customisation/expressionengine/lg- quarantine/

Extensions 'Take control'

Strengths • Extend existing tags • Extend control panel • Built in settings form - can be extended • All through hooks

Strengths Weaknesses • Extend existing tags • Must be activated • Extend control panel • No tag parsing • Built in settings form - • Hook registration + can be extended setting complexity • All through hooks

Hooks • Hook into the core EE processing • Over 170 hooks http://expressionengine.com/developers/extension_hooks/ • Hooks in use http://devot-ee.com/hooks/ • Extension class method called by EE when hook executed

Creating Hooks • Insert row into exp_extensions DB table • class: The current extension class • hook: The hook that calls the method • method: The class method to call • version: Extension version • settings: Serialised array of settings

EE Hook

EE Extension Hook method

Passes data EE Extension Hook method

Passes data EE Extension Hook method Returns modiﬁed data

Always check if someone else is using the same hook public function my_hook_method($html){ $this->get_last_call($html, ''); } /** * Get the last call from a previous hook * * @access private * @param mixed $param The variable we are going to ﬁll with the last call * @param mixed $default The value to use if no last call is available */ private function get_last_call(&$param, $default = NULL){ global $EXT; if ($EXT->last_call !== FALSE) $param = $EXT->last_call; else if ($param !== NULL && $default !== NULL) $param = $default; }

FieldFrame • Developed by: Brandon Kelly • Easily add custom ﬁelds • Integrates with SAEF • http://brandon-kelly.com/ ﬁeldframe

NSM Publish Plus • Developed by: Newism • Publishing workﬂow, drafts and revisions • Member publishing permissions • http://leevigraham.com/cms- customisation/expressionengine/ nsm-publish-plus/

Addons

Strengths • Powerful: Can change every aspect of an install • Combined strengths of all the components

Strengths Weaknesses • Powerful: Can change • Lots of ﬁles in many every aspect of an install different locations • Combined strengths of • Dependency on all the components components

Structure • Developed by: Travis Schmeisser • Organise EE content in a control panel module • Output navigation in the front end w/ custom tags • http://buildwithstructure.com/

LG Better Meta • Developed by: Leevi Graham • Add entry meta in a publish form custom tab • Output meta on the front end w/ custom tags • http://leevigraham.com/cms- customisation/expressionengine/ lg-better-meta/

Finding addons • Ofﬁcial Repository (144) http://expressionengine.com/downloads/addons/ • ExpressionEngine Forums (?) http://expressionengine.com/wiki/ • Devot:ee (480) http://devot-ee.com/add-ons/ • GitHub (114) http://github.com/search?q=ee_addon&type=Repositories • http://leevigraham.com http://leevigraham.com/cms-customisation/expressionengine/

Developing your own addons http://expressionengine.com/docs/development/ http://expressionengine.com/developers/ extension_hooks/

What will it do? Plugin Module Extension Addon Settings x x x Custom ﬁelds x x Custom tabs x x Custom tags x x x Modify existing tags x x Field text formatting x x Core manipulation x x Language ﬁles x x x Database tables x x x Process front end forms x x x

GitHub.com

nsm.custom_tab.ee_addon

/system /extensions /ext.nsm_custom_tab_ext.php /language /english /lang.custom_tab.php Addon /lang.custom_tab_ext.php /lib /nsm_custom_tab /views Folder /nsm_custom_tab /index.php /nsm_custom_tab_ext Structure /form_settings.php /publish_tab.php /modules /nsm_custom_tab /mcp.nsm_custom_tab.php /mod.nsm_custom_tab.php /themes /cp_themes Not so simple /nsm_custom_tab /admin.css /admin.js /site_themes /nsm_custom_tab /index.php /entry.php

/system /extensions /ext.nsm_custom_tab_ext.php /language /english /lang.custom_tab.php /lang.custom_tab_ext.php /lib /nsm_custom_tab /models /updates /views /nsm_custom_tab /index.php /nsm_custom_tab_ext /form_settinings.php /publish_tab.php /modules /nsm_custom_tab /mcp.nsm_custom_tab.php /mod.nsm_custom_tab.php

/themes /cp_themes /nsm_custom_tab /admin.css /admin.js /site_themes /nsm_custom_tab /index.php /entry.php

! Code ahead !

Kicking off ext.nsm_custom_tab_ext.php Class Nsm_custom_tab_ext(){ var $name = 'NSM Custom Tab'; var $version = '1.0.0'; var $description = 'Adds a custom tab'; var $settings_exist = 'y'; var $docs_url = ''; public function __construct($settings=FALSE){ $this->settings = $setttings; } }

Add hooks var $hooks = array( 'lg_addon_update_register_source', 'lg_addon_update_register_addon', 'publish_form_new_tabs', 'publish_form_new_tabs_block', 'submit_new_entry_start', 'submit_new_entry_end', 'publish_form_start' ); public function enable_extension(){ global $DB; foreach($this->hooks as $hook){ // insert the hook into the exp_extensions table w/ // $this->settings } }

Implement settings public function settings_form($current_settings){ // add the page title // build crumb navigation // add PayPal donations button? // link to the module dashboard page? // link to help? ob_start(); include(PATH_EXT.'nsm_custom_tab_ext/views/form_settings.php'); $out .= ob_get_clean(); return $out; } public function save_settings(){ // process & serialize $_POST // save to exp_extension_settings table }

Add the tab // Add the tab public function publish_form_new_tabs($publish_tabs, $weblog_id, $entry_id) { $this->get_last_call($publish_tabs); $publish_tabs['tab_id'] = 'Tab label'; return $publish_tabs; }

Add the tab content // Add the tab content public function publish_form_new_tabs_block(){ $this->get_last_call($out, ''); $data = $this->get_tab_data(); ob_start(); include(PATH_EXT.'nsm_custom_tab_ext/views/tab.php'); $out .= ob_get_clean(); return $out; } // Get the tab content and merge in the preview / revision private function get_tab_data(){ $data = array('foo' => 'bar'); // merge the post data $post = $IN->GBL('Nsm_custom_tab_ext', 'POST'); return array_merge($data, $post); }

Process the submission // Validate the submission data public function submit_new_entry_start( $which, $errors, $entry_id){ global $IN; $data = $IN->GBL('Nsm_custom_tab_ext'); if($data['foo'] == '') $errors .= '<br />Another Error!'; if($errors){ $EE->new_entry_form('preview', $errors, $entry_id); $EXT->end_script = TRUE; } } // Save the submission data public function submit_new_entry_end($entry_id, $data){ // Take the post data and do what you need to like save to the database }

Quicksave // Runs before any data is processed public function publish_form_start($which, $error, $entry_id, $hidden){ global $IN; if(empty($entry_id)) $entry_id = $IN->GBL('entry_id'); // If the $which is save, jump to submit_new_entry_end() if($which == 'save' && $entry_id != FALSE){ $this->submit_new_entry_end($entry_id); } }

LG Addon Updater // register the xml versions source public function lg_addon_update_register_source($sources){ global $EXT; $this->get_last_call($sources); $sources[] = 'http://yoursite.com/versions.xml'; return $sources; } // register this addon public function lg_addon_update_register_addon($addons){ global $EXT; $this->get_last_call($addons); $addons['nsm_custom_tab_ext'] = $this->version; return $addons; }

Next steps

Free LG / NSM addons!

Thankyou. Questions? http://newism.com.au / @newism

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How to start developing your own ExpressionEngine addons

by Leevi Graham on Nov 14, 2009

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