WordPress NepalWordPress Meetup # 13

Laxman Kasula

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

Simple Contact-us Plugin Development

Objective

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

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/

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.

Lets start developing the plugin wpnepal-contacts

A. Prefix Used: wpnepal-contactsB. Files Organization

1. wpnepal-contacts.php (primary file)2. uninstall.php3. 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

1. Create the plugin defination header/* Plugin Name: WPNepal Contacts Form */

2. activate, deactivate and uninstalla. activation: register_activation_hook() --- check the wordpress version --- create the table to store contacts informationb. deactivation: register_deactivation_hook()c. uninstallation:

i. uninstall.php OR ii. register_uninstall_hook() --- drop the contacts info table

3. Action Hooks• to fire a function at a specific point.• ‘plugins_loaded’ action hook: load_plugin_textdomain()

4. Accessing the plugin functionality1. Widgets2. Call functions in templates3. shortcodes

---[wpnepal_contacts_form] with add_shortcode()

5. Include the Contact Form

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 ).

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.

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()

9. Filter • to manipulate the output of the content.• Html email: ‘wp_mail_content_type’ filter

using add_filter()

Improvements: Add Settings Page

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()

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.

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()

Thanks !!!

Questions ???