This document outlines the steps to develop a simple contact form plugin for WordPress. It discusses organizing plugin files, prefixing elements uniquely, registering activation and deactivation hooks, adding shortcodes and settings pages, validating and sanitizing form data, storing submissions in the database, and sending emails. The plugin aims to demonstrate best practices for plugin development like using actions, filters, options and settings APIs to integrate the form functionality throughout WordPress.

1. WordPress Nepal
WordPress Meetup # 13

2. Laxman Kasula
PHP Developer (Primarily focused on
WordPress) @ Ingenious IT Pvt. Ltd.
e-mail: laxman.kasula@gmail.com

3. Simple Contact-us Plugin Development

4. Objective
• To develop a simple plugin that would
motivate to develop the complex plugin.

5. WordPress Plugin
• A single file or a group of files inside a folder
to add features to WP.
• Put the plugin into plugins folder (wp-
content/plugins) and activate from plugins
menu in the backend.
• WordPress Plugins Repository:
http://wordpress.org/extend/plugins/

6. Plugin Development Good Practices
1. Organize Files
• main plugin file and uninstall.php in the folder
and all others in subfolders like js, css,
includes, images …
2. Prefix Everything
• uniquely prefix every variables and functions.

7. Lets start developing the plugin
wpnepal-contacts

8. A. Prefix Used: wpnepal-contacts
B. Files Organization
1. wpnepal-contacts.php (primary file)
2. uninstall.php
3. css
• wpnepal-contacts-form.css
4. js
• wpnepal-contacts-custom-script.js
• jquery-ui-1.8.18.custom.min.js
• jquery.validate.js
• gen_validatorv31.js
5. includes
• wpnepal-contacts-table.php
• wpnepal-contacts-form.php
• wpnepal-general-functions.php
• wpnepal-admin-settings.php
• captcha_code_file.php
• monofont.ttf

9. 1. Create the plugin defination header
/* Plugin Name: WPNepal Contacts Form */
2. activate, deactivate and uninstall
a. activation: register_activation_hook()
--- check the wordpress version
--- create the table to store contacts information
b. deactivation: register_deactivation_hook()
c. uninstallation:
i. uninstall.php OR
ii. register_uninstall_hook()
--- drop the contacts info table

10. 3. Action Hooks
• to fire a function at a specific point.
• ‘plugins_loaded’ action hook: load_plugin_textdomain()
4. Accessing the plugin functionality
1. Widgets
2. Call functions in templates
3. shortcodes
---[wpnepal_contacts_form] with add_shortcode()
5. Include the Contact Form

11. 6. Add the css and js files to the page
• ‘template_redirect’ action
• wp_enqueue_style() and wp_enqueue_script()
• wp_localize_script()
--- all ajax request are sent to admin-ajax.php (
wp-admin directory ).
--- pass dynamic variable to the js file ( path of
admin-ajax.php and the nonce value ).

12. 7. NONCE (Number used ONCE)
• Specific to:
– One WP user
– one action (delete, update, edit...)
– one object (a post, a link, a plugin setting)
– one time frame of 24 hours
• Example: ‘action=process-wpnepal-contacts-
form&wpnepal_contacts_form_nonce=eb587a5939’
--- nonce value ‘eb587a5939’ is valid for only 24
hours to only action ‘process-wpnepal-contacts-
form‘ and only for only you.
• WP verifies if the nonce meets all the criterias before
processsing the actions.

13. 8. Process the form action
• process the action parameter using 2 ajax actions
1. wp_ajax_$action
--- hooks functions if the user is logged in.
2. wp_ajax_nopriv_$action
--- hooks functions if the user is not logged in and
has no privilege.
• verify nonce: wp_verify_nonce()
• if verified, sanitize and validate the obtained
data.
• insert into the table: $wpdb->insert()
• send an email: wp_mail()

14. 9. Filter
• to manipulate the output of the content.
• Html email: ‘wp_mail_content_type’ filter
using add_filter()

15. Improvements: Add Settings Page

16. 10. Adding Settings Page to WP Backend
• Menus
– Action: ‘admin_menu’
add_menu_page()
add_submenu_page( )
add_plugins_page()
add_theme_page()
• Handling Options
– Use Options API and Settings API to properly save the
options in a WP manner.
– Options API:
add_option(),
update_option(),
get_option(),
delete_option()

17. 11. Settins API
• 3 Components
1. Fields
--- individual options: textbox, radio, checkbox
--- add_settings_field()
2. Sections
--- logical group of fields
--- add_settings_section()
3. Settings
--- ( Fields + Sections )
--- register_setting()
• Rendering Options to the Page
– settings_fields(): takes care of rendering several security
measures for the options form.
– do_settings_sections(): actually renders the options to the
page.

18. 12. Actions Encountered
– init, admin_init
– plugins_loaded
– template_redirect
– wp_print_styles, wp_print_scripts
– wp_ajax_, wp_ajax_nopriv_
– admin_menu
13. Filters Encounterd
– wp_mail_content_type
14. Functions Encounterd
– plugin_dir_path(), plugin_dir_url()
– register_activation_hook(), deactivate_plugins(), register_deactivation_hook()
– get_bloginfo()
– add_shortcode()
– load_plugin_textdomain()
– is_page()
– wp_enqueue_style,() wp_enqueue_script(), wp_localize_script()
– wp_create_nonce(), wp_verify_nonce()
– add_option(), get_option()
– Is_email(), wp_mail()
– add_menu_page()
– add_settings_section(), add_settings_field(), register_setting()
– settings_fields(), do_settings_sections()
– dbDelta()

19. Thanks !!!

20. Questions ???