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

2. 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

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

4. Plugins

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

6. 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

7. 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/

8. 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}

9. Modules

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

11. 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

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

13. 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/

14. 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/

15. 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/

16. Extensions
'Take control'

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

18. 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

19. 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

20. 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

21. EE
Hook

22. EE Extension
Hook method

23. Passes data
EE Extension
Hook method

24. Passes data
EE Extension
Hook method
Returns modified data

25. 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;
}

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

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

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

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

30. Addons

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

32. 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

33. 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/

34. 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/

35. 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/

36. 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/

37. 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/

38. 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/

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

40. 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

41. GitHub.com

42. nsm.custom_tab.ee_addon

43. /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

44. /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

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

46. ! Code ahead !

47. 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;
}
}

48. 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
}
}

49. 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
}

50. 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;
}

51. 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);
}

52. 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
}

53. 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);
}
}

54. 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;
}

55. Next steps

57. Free LG /
NSM addons!

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