WordPress basic fundamental of plugin development and creating shortcode

© Copyright 2010 Nibiru Solutions Private Limited 1
Presented by: Rakesh

2© Copyright 2010 Nibiru Solutions Private Limited 2
Agenda
Introduction
How to create wordpress plugin
How to create shortcode
How to create theme option
Quiz Questions

Introduction
This session is very important and its very interesting.
In this session I cover some important worpress prebuild function
And there uses
Deep understanding of creating worpress plugin.
Creating wordpress shortcode and uses.
How to create theme options and uses

How To Create Wordpress Plugin
WordPress is not just a blogging platform and it is such a
powerful CMS with unlimited capabilities, besides having
a huge user base.
Almost anything can be scripted with wordpress. You can
extend wordpress either by means of plugin or by a theme.
i will show you how to write a “Hello World” wordpress
plugin, which unlike many believe is surprisingly easy,
once you understand the very fundamentals.

How To Create Wordpress Plugin -2
Plugin Files & Names
1. Always you chose a unique name to your plugin so that it doesnt
collide with names used in other plugins.
2. Assigning unique names, documenting and organizing the
plugin files is very important part of plugin creation.
3- place the plugin php file directly into the wp-
content/plugins folder
http://wordpress.org/plugins/about/readme.txt

The Plugin Basics
The heart of a wordpress plugins is the below 2 functions
(commonly called `hooks`)
add_action ($tag, $func)
add_filter ($tag,$func)
add_action –> does an action at various points of wordpress
execution
add_filter –> does filtering the data (eg. escaping quotes before mysql
insert, or during output to browser.

Plugin Information
Open your hello-world.php and in the first line, add this commented plugin
information to your file.
<?php
/*
Plugin Name: Hello-World Plugin
URI: http://yourdomain.com/
Description: A simple hello world wordpress plugin
Version: 1.0
Author: Your Name
Author URI: http://yourdomain.com
License: GPL
*/
?>
Save file.

Go to your wordpress admin > plugins and you will see the new
plugin listed, waiting to get activated.
But this plugin had to do something right?
-> For that we write the code using add_action below the commented plugin
information in the hello-world.php

<?php
/* This calls hello_world() function when wordpress initializes.*/
add_action('init','hello_world');
function hello_world() {
echo "Hello World";
}
?>
And Your Plugin done!
When our plugin is activated, add_action command calls our hello_world() function
when wordpress starts loading.
To test Open Any index.php , page.php or single.php And place the
following code.
<?php
if(function_exists('hello_world')) {
hello_world();
}
?>

Build a plugin options page in admin area :
The plugin outputs hello world (its pretty much static).
So make this to dynamic we need to create a good admin interface.
Here is what we do….
We create a options menu for Hello World in WordPress Admin > Settings.
We save the user entered data in the wordpress database. Using set_options()
function.
We retrieve the data stored in wordpress database and output it using
get_options() function.

Activating/Deactivating Plugin
It is very easy to write a function on what plugin does, when it gets
activated. WordPress offers 4 very important functions
register_activation_hook -> Runs on plugin activation
register_deactivation_hook -> Runs on plugin deactivation
add_option -> Creates new database field
get_option -> Retrieves the value in database field.

Activating/Deactivating Plugin -2
Example : write fallowing code in hello-word.php
<?php
/* Runs when plugin is activated */
register_activation_hook(__FILE__,'hello_world_install');
/* Runs on plugin deactivation*/
register_deactivation_hook( __FILE__, 'hello_world_remove' );
function hello_world_install() {
/* Creates new database field */
add_option("hello_world_data", 'Default', '', 'yes');
}
function hello_world_remove() {
/* Deletes the database field */
delete_option('hello_world_data');
}
?>

Plugin Settings Page
All we need to create is plugin settings page in the wordpress admin area.
<?php if ( is_admin() ){
/* Call the html code */
add_action('admin_menu', 'hello_world_admin_menu');
function hello_world_admin_menu() {
add_options_page('Hello World', 'Hello World', 'administrator', 'hello-world',
'hello_world_html_page');
}
} ?>
Here is a very important thing to remember:
The add_action for admin_menu should call a function
hello_world_admin_menu() containing add_options_page, which in turn
should call a function hello_world_html_code() containing html code.
This is how the code should flow! Refer to wordpress administration menus

Plugin Settings Page – Coding Part -1
The below function has the html code for the settings page,
containing the form
<?php
function hello_world_html_page() {
?>
<div>
<h2>Hello World Options</h2>
<form method="post" action="options.php">
<?php wp_nonce_field('update-options'); ?>
<table width="510">
<tr valign="top">
<th width="92" scope="row">Enter Text</th>
<td width="406">

<input name="hello_world_data" type="text" id="hello_world_data"
value="<?php echo get_option('hello_world_data'); ?>" />
(ex. Hello World)</td>
</tr>
</table>
<input type="hidden" name="action" value="update" />
<input type="hidden" name="page_options" value="hello_world_data" />
<p>
<input type="submit" value="<?php _e('Save Changes') ?>" />
</p>
</form>
</div>
<?php } ?>

And finally your plugin ready and looks like following.
You must remember 2 things in the above code.
1. Specify the database field we created before in the input text box as `hello_world_data`.
<input name="hello_world_data" type="text" id="hello_world_data“ value="<?php echo
get_option('hello_world_data'); ?>" />
2. If your form has number of fields (like textbox, selectbox etc), all those should be listed
in the value field of page_options, separated by commas. For more information, refer
to wordpress documentation
<input type="hidden" name="page_options" value="hello_world_data" />

Wwordpres Shortcode
The Shortcode API
 Introduced in WordPress 2.5
 A simple set of functions for creating macro codes for use in post content.
 And a simple shortcode used like [shotcode].
Lets Create a shortcode of Hello Word plugin
<?php
function show_hello_text() {
return get_option('hello_world_data');
}
add_shortcode('showtext', 'show_hello_text');
?>
Use the shortcode [showtext] into page or post content to show your hello world text.

How to create custom them option
If you create your own themes you will, sooner or later, want to allow
your theme users have some control over certain appearance and/or
functional elements of your theme.

How to create custom them option -2
This commonly use following functions.
add_action( $tag, $function_to_add, $priority, $accepted_args );
register_setting( $option_group, $option_name, $sanitize_callback )
add_theme_page( $page_title, $menu_title, $capability, $menu_slug, $function );
settings_fields( $option_group )
## coding section
<? php
add_action( 'admin_init', 'theme_options_init' );
add_action( 'admin_menu', 'theme_options_add_page' );
function theme_options_init(){
register_setting( 'sample_options', 'sample_theme_options');
}
function theme_options_add_page() {
add_theme_page( __( 'Theme Options', 'sampletheme' ), __( 'Theme
Options', 'sampletheme' ), 'edit_theme_options', 'theme_options',
'theme_options_do_page' );
}
1- this used in setting_fields();
2- this function name and its used html

How to create custom them option -3
function theme_options_do_page() {
global $select_options;
<form method="post" action="options.php">
<?php settings_fields( 'sample_options' ); ?>
<?php $options = get_option( 'sample_theme_options' ); ?>
<input id="sample_theme_options[showintro]" name="sample_theme_options[showintro]"
type="checkbox" value="1“ <?php checked( '1', $options['showintro'] ); ?> />
<input id="sample_theme_options[fburl]" type="text"
name="sample_theme_options[fburl]" value="<?php esc_attr_e( $options['fburl'] ); ?
>" />
<textarea id="sample_theme_options[introtext]"
class="large-text" cols="50" rows="10" name="sample_theme_options[introtext]"><?php
echo esc_textarea( $options['introtext'] ); ?></textarea>
<input type="submit" value="<?php _e( 'Save Options', 'customtheme' ); ?>" />
</form>
} ?>
1
2

The End Of Then Session
Thank You !

WordPress basic fundamental of plugin development and creating shortcode

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