Word Press Plug In Development Short Tutorial

The first steps… • Pre‐development issues – Wordpress Plugin Directory – Plugin and File Names – File Headers

• Wordpress Plugin Hooks  – Actions  – Filters

• Adding data to wordpress database – Creating tables with plugins

• Adding Administration Menus – Creating options page

• “Hello Dolly” example 11/10/2008

Wordpress Plugin Development ‐ A Short  Tutorial

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Pre‐development issues (1) Wordpress Plugin Directory  code

javascript

wp‐content

plugins

your plugin

place your plugin here

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Wordpress Plugin Development ‐ A Short  Tutorial

css

images

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Pre‐development issues (2) Plugin and File Names Choose  your  plugin’s name  carefully.  Think  about  what the plugin will do, and make a, hopefully unique,  name for it. 

It is good for the names of your php files to be derived  from your chosen plugin name.

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Wordpress Plugin Development ‐ A Short  Tutorial

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Pre‐development issues (3) File Headers

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Wordpress Plugin Development ‐ A Short  Tutorial

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Wordpress Plugin Hooks (1) Hooks are provided to allow your plugin to 'hook into' the rest of WordPress; that is, to call functions in your plugin at specific times, and thereby set your plugin in motion.

Hooks

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Wordpress Plugin Development ‐ A Short  Tutorial

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Wordpress Plugin Hooks (2) Hooks = Actions + Filters Actions are triggered by specific events (e.g. publishing a post ) that take place in WordPress. Your plugin can respond to the event by executing a PHP function

Event

Action 11/10/2008

Wordpress Plugin Development ‐ A Short  Tutorial

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Wordpress Plugin Hooks (3) Hooks = Actions + Filters Filters - Functions

DATA

Filters are functions that WordPress passes data through at certain points in execution, just before taking some action with the data such as adding it to the database or sending it to the browser screen. 11/10/2008

Wordpress Plugin Development ‐ A Short  Tutorial

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Adding data to Wordpress database Create tables with plugins There are two types of information you could store • Setup Information: user choices that are entered when the user first sets up your plugin. • Data: information that is added as the user continues to use your plugin Steps… 1. Write a PHP function that creates the table. 2. Ensure that WordPress calls the function when the plugin is activated. 3. Create an upgrade function, if a new version of your plugin needs to have a different table structure.

http://codex.wordpress.org/Creating_Tables_with_Plugins#Create_Database_Tables 11/10/2008

Wordpress Plugin Development ‐ A Short  Tutorial

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A simple example $table_name = $wpdb->prefix . "liveshoutbox";

// check if there is a table with the same name if($wpdb->get_var("show tables like '$table_name'") != $table_name) {

// SQL Statement $sql = "CREATE TABLE " . $table_name . " ( id mediumint(9) NOT NULL AUTO_INCREMENT, time bigint(11) DEFAULT '0' NOT NULL, name tinytext NOT NULL, text text NOT NULL, url VARCHAR(55) NOT NULL, UNIQUE KEY id (id) );";

// Creating the table require_once(ABSPATH . 'wp-admin/includes/upgrade.php'); dbDelta($sql);

A simple example $welcome_name = "Mr. Wordpress"; $welcome_text = "Congratulations, you just completed the installation!";

// SQL Statememt $insert = "INSERT INTO " . $table_name . " (time, name, text) " . "VALUES ('" . time() . "','" . $wpdb->escape($welcome_name) . "','" . $wpdb->escape($welcome_text) . "')";

// Adding Data into the table $results = $wpdb->query( $insert );

Adding Administration Menus Create options page Top-level menus: Settings, Manage, Plugins, Presentation, Write, Users

Admin Menu Functions • add_menu_page: create a top-level menu • add_submenu_page: define one or more sub-menu pages In the above wordpress functions the developers defined the name of their php functions which are responsible to build the options pages. See an example here http://codex.wordpress.org/Creating_Options_Pages

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Wordpress Plugin Development ‐ A Short  Tutorial

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Hello Dolly example

Hello Dolly Lyrics

Chose randomly one lyric and place it the upper right of your Administation panels

add_action('admin_footer', 'hello_dolly');

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Wordpress Plugin Development ‐ A Short  Tutorial

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Wordpress Development Community Are you ready to enter into an evolving development community?

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Wordpress Plugin Development ‐ A Short  Tutorial

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Matt Mullenweg Creator of Wordpress.org

14th place The 25 most influential people on the web (2008)

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Wordpress Plugin Development ‐ A Short  Tutorial

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More details on the internet… The truth is out there… http://codex.wordpress.org/Writing_a_Plugin#WordPress_Plugin_Hooks http://codex.wordpress.org/Plugin_API http://codex.wordpress.org/Creating_Tables_with_Plugins http://codex.wordpress.org/Adding_Administration_Menus

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Wordpress Plugin Development ‐ A Short  Tutorial

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THE END

Thank you! 11/10/2008

Wordpress Plugin Development ‐ A Short  Tutorial

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