simple-settings-example

<?php
/**
 * Plugin Name: Simple Settings Example
 * Description: Minimal settings page with one text field.
 * Version: 1.0
 */

if (!defined('ABSPATH')) {
    exit;
}

class SimpleSettingsExample {

    private $option_name = 'simple_settings_example_text';

    public function __construct() {
        add_action('admin_menu', [$this, 'register_settings_page']);
        add_action('admin_init', [$this, 'register_settings']);
    }

    public function register_settings_page() {
        add_options_page(
            'Simple Settings',
            'Simple Settings',
            'manage_options',
            'simple-settings-example',
            [$this, 'render_settings_page']
        );
    }

    public function register_settings() {
        register_setting('simple_settings_group', $this->option_name);
    }

    public function render_settings_page() {
        ?>
        <div class="wrap">
            <h1>Simple Settings</h1>

            <form method="post" action="options.php">
                <?php
                settings_fields('simple_settings_group');
                $value = get_option($this->option_name, '');
                ?>

                <table class="form-table">
                    <tr>
                        <th scope="row">Text option</th>
                        <td>
                            <input type="text"
                                   name="<?php echo esc_attr($this->option_name); ?>"
                                   value="<?php echo esc_attr($value); ?>"
                                   class="regular-text">
                        </td>
                    </tr>
                </table>

                <?php submit_button('Save Settings'); ?>
            </form>
        </div>
        <?php
    }
}

new SimpleSettingsExample();