This document discusses add-on development for ExpressionEngine. It covers what add-ons are, including extensions, modules, and plugins. It discusses necessary development skills like PHP, SQL, and HTML/CSS. It provides guidance on planning add-on development through researching, mapping features, designing templates and control panels. The document also covers writing code through following best practices, debugging, and improving performance. Developers are encouraged to turn on debugging, review queries, consider caching, remove deprecated code, and ask for help when needed.

1. Add-On Development:
EE Expects that Every
Developer will do his Duty
Paul Burdick, Lead Developer
solspace
http://solspace.com/downloads/eeci2009/presentation.txt

2. Summary of Talk
• What are Add-Ons?
• The Three Types of Add-Ons in EE
• Overview of Accessories in EE 2.x
• Add-On Development Skills
• Developing Add-Ons in ExpressionEngine
• Writing Code
• Debugging & Improving Performance

3. Summary of Talk
• What are Add-Ons?
• The Three Types of Add-Ons in EE
• Overview of Accessories in EE 2.x
• Add-On Development Skills
• Developing Add-Ons in ExpressionEngine
• Writing Code
• Debugging & Improving Performance

4. I.
What are Add-Ons?

5. Three Types of Add-Ons in
EE 1.x and 2.x
• Extensions
• Modules
• Plugins

6. Extensions

7. • Extends the base functionality of
ExpressionEngine
• Allows developers to interpose their own
code into EE's codebase.
• Restrained by where hooks are placed in
the code and what arguments are sent with
the extension call

8. • More and more Third Party developers are
adding hooks to their own code, allowing
extensions for Third Party Add-Ons. Pretty
darn cool.
• Typically no DB tables, but there are always
exceptions
• Settings Form CP

9. function settings()
{
$settings = array();
$settings['butter'] = "Quite Tasty";
$settings['buttery'] = array('r', array('yes' => "yes", 'no' => "no"), 'no');
// Complex:
// [variable_name] => array(type, values, default value)
// variable_name => short name for setting and key for language file variable
// types: t - textarea
// r - radio buttons
// s - select
// ms - multiselect
// f - function calls
// values: can be array (r, s, ms), string (t), function name (f)
// default: name of array member, string, nothing
//
// Simple:
// [variable_name] => 'Butter'
// Text input, with 'Butter' as the default.
return $settings;
}

11. Modules

12. • The Mighty Workhorses of EE
• Complete and expansive Control Panels.
• Database Tables
• Template Tags
• Own extensions possible

13. Plugins

14. • No settings, no tables, no CP, no install
• Text manipulation either via Template Tags
or Custom Fields
• Or, functionality "plugged" into your
Templates.

15. Add-On Quantities @ devot-ee.com
18 October 2009
Extensions: 170
Modules: 73
Plugins: 248

16. Examples of Extensions
• Edit Tab AJAX - AJAX enabled search for
Control Panel's Edit area
• FieldFrame - Easily create new custom field
types for ExpressionEngine.
• LG Add Sitename - Site Label in upper left of
your CP

17. Examples of Modules
• Structure - Create Static and Listing pages,
editable via a tree sitemap
• Tag - Folksonomy functionality for Weblog and
Gallery Entries
• User - EE's Member Functionality in Templates

18. Examples of Plugins
• EE Gravatar - Global Avatars for site members
• Image Sizer - Resizes and caches images on the
fly
• Markdown - Markdown formatting in EE
Custom Weblog Fields

19. Accessories
in EE 2.0

20. • Accessories provide tools, references, or
abilities at the bottom of your EE Control
Panel in ExpressionEngine 2.0
• No CP page for each Accessory
• Can have own DB tables
• View files! Lovely lovely View files!

22. II.
Add-On
Development Skills

23. PHP

24. • Duh...
• PHP: Hypertext Preprocessor. You really
have to love recursive acronyms.
• Server side programming language.
Processed at runtime.
• No Compiling! Viewable Source!

25. • PHP files contain code, but they can also
have HTML, JS, XML, et cetera inside them.
• Extremely widespread on hosting
environments.

26. PHP Learning References
PHP Docs: http://php.net/manual/
W3C Tutorial: http://www.w3schools.com/PHP/php_intro.asp
Zend Tutorial: http://devzone.zend.com/article/627

27. SQL

28. • Required for advanced Add-On development
• Active Record only *helps* build queries

29. MySQL
• Popular, open-source, relational database.
• Simple to setup and administrate.
• Fast for reading, decent for writing
• Dominant on hosted environments

30. MySQL Learning References
• MySQL Docs: http://dev.mysql.com/doc/
• Buy a book. ( O'Reilly Books are well done )
• Learn JOINs
• http://www.informit.com/articles/article.aspx?
p=30875&seqNum=5
• http://en.wikipedia.org/wiki/Join_(SQL)

31. HTML/CSS

32. View Files
• Essentially HTML files with PHP inside for
outputting data
• Part of ExpressionEngine 2.0 by default
• Available in ExpressionEngine1.x using Hermes
or custom include code

33. <?php echo $this->view('header.html');?>
<h4 class="alertHeadingCenter"><?php echo $LANG->line('error');?></h4>
<div class='defaultCenter' >
<div class="box">
<strong><?=$error_message?></strong>
<br /><br />
<strong>
<a href='javascript:history.go(-1)'>&#171; <?=$LANG->line('back')?></a>
</strong>
</div>
</div>
<?php echo $this->view('footer.html'); ?>

34. User Interfaces
• Build in static HTML, CSS, JS files before converting
to View files.
• Easier development.
• Easier bug testing.
• No need to create data variables/objects first.
• UI developer does not need to understand PHP.

35. jQuery/JavaScript

36. • jQuery available in EE 1.x via an extension
(not enabled by default)
• jQuery available in EE 2.x with no additional
work
• Relatively easy to add other libraries or
custom JS if need be.

37. global $EXT;
if ( ! isset($EXT->version_numbers['Cp_jquery']))
{
return $OUT->show_user_error('general', $LANG->line('cp_jquery_requred')));
}

38. III.
Developing Add-Ons
in ExpressionEngine

39. Never, Ever Just
Start Coding!

41. Research
• Previous Approaches
• Required Features
• Alternative Approach in ExpressionEngine?
• Can this be done in EE in any other way?
• Is a Module required? Could an Extension do it?
• Could a Plugin output weblog data in the way you
need?

42. Tell a Story
• How will Person A do Task 1?
• Question Previous Approaches.
• Is X Really the BEST way to do it?
• What Would Apple Do?
• Eliminate Steps, Make Process Intuitive.
• Follow your instincts.

43. Map Out Features
• Major
• Functionality required for module to serve
its market/purpose
• Minor
• Not Necessarily Required.
• Features are cuttable for a 1.0 release.
• Icing
• For specific clients or users
• Think and consider them

44. Database Structure
• Tables for your Major and Minor Features
• Normalization: Eliminate Data Duplication
• http://en.wikipedia.org/wiki/Database_normalization
• Indexes!
• Specific, Sensical Field Names
• 'event_title' vs 'event'
• 'event_short_name' vs 'name'

45. Tags Structure
• The Naming and Functionality of Template tags
• For Each Tag
• Describe
• Name
• Parameters
• Variable Pairs and Single Variables
• Consider this a precursor to your documentation

46. Tags Structure: Describe
• Descriptions for each Tag, Parameter, and Variable.
• Explain what each one does.

47. Tags Structure: Tag Name
• Simple and Obvious
• No Abbreviations, No Ambiguity
• {exp:module:g_entries} vs
{exp:module:gallery_entries}

48. Tags Structure: Parameters
• Prefix?
• form:id="" or form_id=""
• Use prefixes to break up parameters into
"groups" of functionality.
• notify:admin_email=""
• notify:user_email=""

49. Tags Structure: Variables
• No Ambiguity, No Abbreviations
• {group}{/group} vs
{category_group}{/category_group}
• {title} vs {event_title}
• Prevent collisions in nested tags
• Underscores recommended

50. Tags Structure:
Show to Other People
• Get Feedback
• Revise until the Spec feels solid.

51. Building a
Control Panel

52. Workflow Module’s CP

53. Control Panel:
Break Up into Sections
• Data Adding, Deleting, and Manipulation
• Create/Modify/Delete Items
• Ex: Calendar, Wiki, Forum
• Build only one main interface
• Preferences/Settings/Permissions
• Per Site, Per Weblog, Per Member Group, Per X
• Actions
• Ex: Recount, Re-Cache, Clear Caches
• Version Number and Documentation Link

54. KISS:
Keep It Simple, Stupid

55. Control Panel: Design
• Build an HTML/CSS/JS mockup first
• Put into a View file
• PHP into HTML, Not HTML into PHP
• documentDOM in Hermes - Builds HTML in
PHP, specifically form fields
• Ignore IE6
• EE 2.x no longer supports it
• Solspace no longer supports it
• Neither should you.

56. Time Wasted on IE6
Making Software Support IE6 vs. Upgrading Users

57. Time Wasted on IE6
Making Software Support IE6 vs. Upgrading Users
92% 8%

58. Have Goals,
Even Milestones,
Never Deadlines

59. IV.
Writing Code

60. Follow the EllisLab
Development Guidelines!
http://expressionengine.com/docs/development/guidelines/index.html

61. "Prolific and informative commenting
using proper comment style"
• We want to know your thinking! Why this way?
• Expect people to learn from your code.
• Helps you understand your *own* logic

62. Sanitize and Escape Everything
• Be Paranoid! Nothing is Immune! Constant
Vigilance!
• If you DID NOT set or get data yourself, assume
it is tainted, even EE variables
• If you DID set or get yourself, but not within ten
lines of code, assume it is tainted.
• Sanitize and Escape at the Query
• No Security Exceptions for SuperAdmins

63. Abstraction
• Use Twice, Write Once
• Create Libraries!
• Reduces Work and Mistakes
• Purpose of Hermes

64. Simplify,
Simplify,
Simplify

65. Simplify: Reduce Code Work
• Do the Least Amount of Effort to produce results
• Bail Out First, Work Second
• Invalid variable type? Bail.
• No Permissions? Bail.
• Error? Bail.
• Don’t Do Serious Work Until You Know You Have
Work To Do

66. Simplify: Reduce DB Work
• Performing Multiple Queries are OK.
• Validate, Check Pagination, Then Retrieve Data

67. Simplify: Models
• Abstract common SELECTs into separate methods
• INSERTs/UPDATEs for a DB Table in one method
• Hermes has per Add-On model caching caching
built into it.
• Speaking of caching...

68. Per Page Load Caching
• Use $SESS->cache
• Suggested:
• $SESS->cache['modules']['module_name']['some_cache'] = array();
• Alternative:
• $SESS->cache['Solspace']['module_name']['some_cache'] = array()
• Try a Reference!
• $this->cache =& $SESS->cache['modules']['module_name'];
• $this->cache[‘some_cache’] = array();

69. Weblog Module Class
• Very powerful code, no need to write your own.
• Code was written so that it could be used elsewhere.
• Returns Results based on tag parameters
• You can modify $TMPL->tagparams!

70. require_once PATH_CORE.'core.typography'.EXT;
require_once PATH_MOD.'/weblog/mod.weblog'.EXT;
$TMPL->tagparams['entry_id'] = '1|2|3|4';
$TMPL->tagparams['dynamic']
= 'off';
$TMPL->tagdata = $TMPL->assign_relationship_data( $TMPL->tagdata );
$TMPL->var_single = array_merge( $TMPL->var_single, $TMPL->related_markers );
$weblog_object = new Weblog;
$weblog_object->fetch_custom_weblog_fields();
$weblog_object->fetch_custom_member_fields();
$weblog_object->fetch_pagination_data();
$weblog_object->create_pagination();
$weblog_object->build_sql_query();
if ($weblog_object->sql == '') return $this->return_data = $TMPL->no_results();
$weblog_object->query = $DB->query($weblog_object->sql);
if ($weblog_object->query->num_rows == 0) return $this->return_data = $TMPL->no_results();
$weblog_object->TYPE = new Typography;
$weblog_object->fetch_categories();
$weblog_object->parse_weblog_entries();
$weblog_object->add_pagination_data();
return $this->return_data = $weblog_object->return_data;

71. Provide Tools for Keeping
Things Tidy
• Removal of Old Data.
• Removal of Old Caches
• Optimize Tables - Reduce DB Overhead

72. V.
Debugging and
Improving Performance

73. Consider Performance
an Aspect of Add-On
Debugging

74. Turn on PHP Debugging
• Insure Display Errors Setting is On in php.ini
• Error Reporting is E_ALL
• No PHP Errors! Ever!
• Remove All Deprecated PHP Functions.

75. Turn on SQL Queries
• Admin => System Preferences => Output and Debugging
• Queries appear on both CP and User side of EE
• Review Queries
• Check the Add-On's CP
• Extensions: Check areas of usage in CP
• Check EVERY single tag in a Template.
• Eliminate Duplicates!

76. Turn on SQL Queries
• Are Certain Queries Necessary on EVERY load?
• Settings/Preferences
• Caching (Checks, Re-caching, Emptying)
• Statistics
• Evaluate Queries for Performance
• Run in phpMyAdmin or similar
• Try Making the Query More Efficient
• Add a WHERE clause on indexed field
• Remove Extraneous JOINs when possible

77. Turn on SQL Queries
• De-Normalization.
• Duplicating Data or Grouping It to Reduce Work
• http://en.wikipedia.org/wiki/Denormalization
• Best example? Statistics: Hit count.
• Abstract methods for data consistency (i.e. correct
values)
• Learn About Optimizing MySQL
• MySQL Performance Blog
• http://mysqlperformanceblog.com

78. SuperSearch SQL Queries

79. Turn on Template Debugging
• Admin => System Preferences => Output and Debugging
• Outputs Elapsed Time during Add-On processing
• What Code is Taking the Longest to Process?
• $TMPL->log_item()
• $TMPL->log_item('Freeform Module: Run Query');
• Disable Processing
• Disable Parameter ( disable="feng_shui" )
• Auto-detect Variables and Remove Queries and
Processing

80. Vanilla Template Log

81. SuperSearch Processing

82. Knowing is Half the Battle!

83. Automated Actions
• Example: Caching or Retrieving Remote Data
• Can Seriously Slow Down an Add-On
• Try AJAX

84. Deprecated Code
• Consider using trigger_error()
• trigger_error('Favorites Module: The Favorites Count
tag has been deprecated. Use the Entry Count tag
instead');
• Don't Leave It Around Forever, Discontinue Support,
Then Remove It

85. Ask for Help
• Plenty of EE, PHP, SQL Knowledge out there. Use it.
• Often just discussing a problem will lead to a solution.

86. V.
Presentation Over, So
Let's Talk