WordPress Settings API quickstart

class-generic-plugin-settings.php

<?php
/**
 * Settings class file.
 *
 * @package  generic-plugin
 */

/**
 * Settings class.
 *
 * The settings for the plugin are handled in this class.
 *
 * @since 1.0.0
 */
class generic_plugin_Settings {

	const PREFIX = '_generic_plugin_';

	/**
	 * Constructor.
	 *
	 * @return  void
	 * @since   1.0.0
	 */
	function __construct() {
		add_action( 'admin_init', array( $this, 'settings_init' ) );
		add_action( 'admin_menu', array( $this, 'settings_menu' ) );
	}

	/**
	 * Add the settings page.
	 *
	 * @return void
	 * @since  1.0.0
	 */
	function settings_menu() {
		add_options_page(
			'Generic Plugin Settings',
			'Generic Plugin Settings',
			'edit_others_posts',
			'generic_plugin',
			array( $this, 'settings_callback' ) 
		);
	}

	function settings_callback() {

	echo '
	<div class="wrap">
		 
		<h1>Generic Plugin Settings</h1>
		<p>Some explanatory text here.</p>

		<h2>Generic Plugin Setting Section 1</h2>
 
		<form method="post" action="options.php">
		';
		do_settings_sections( self::PREFIX . 'settings' );
		settings_fields( self::PREFIX . 'settings_group' );
		submit_button();
		echo '
		</form>
		</div>
		';

	}

	function settings_init() {
 
		 /** Setting section **/
		add_settings_section(
			self::PREFIX. '_section_1_setting',
			'',
			array( $this, 'section_1' ),
			self::PREFIX . 'settings'
		);
		 
		 /** Setting field **/
		add_settings_field(
			self::PREFIX . 'setting_1_name',
			'Setting 1',
			array( $this, 'setting_1_callback' ),
			self::PREFIX . 'settings',
			self::PREFIX . '_section_1_setting'
		);

		// Register this field with our settings group.
		register_setting( self::PREFIX . 'settings_group', self::PREFIX . 'settings' );
		 
	}

	function section_1() {
		echo 'Setting 1 Explanatory Text';
	}

	function setting_1_callback() {

		// get the current option value 
		$settings = get_option( self::PREFIX . 'settings' );

		echo '<input type="text" name="' . self::PREFIX . 'settings[setting_1]' . '" value="' . $settings['setting_1'] .'" />';

	}

	/**
	 * Helper monkeys.
	 *
	 * May include: usort() callbacks, content filters, etc.
	 */

}

new generic_plugin_Settings;