wordpress form with image upload and store to database

<?php
/*


Plugin Name: My Family
Plugin URI:
Description: Plugin for my Family
Version: 0.1.0
Author: David Saerang
Author URI:
*/

// disable direct access
if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

function family_options_install() {
    global $wpdb;
    $table_name = $wpdb->prefix . 'family_survey';
    $wpdb_collate = $wpdb->collate;
    $sql =
    "CREATE TABLE {$table_name} (
        `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
        `nama` varchar(50) DEFAULT NULL,
        `email` varchar(150) DEFAULT NULL,
        `gambar` varchar(50) DEFAULT NULL,
        PRIMARY KEY (`id`)
    )
    COLLATE {$wpdb_collate}";
    require_once(ABSPATH . 'wp-admin/includes/upgrade.php');
    dbDelta( $sql );
}

    // run the install scripts upon plugin activation
    register_activation_hook(__FILE__, 'family_options_install');

    //menu items
//  add_action('admin_menu','family_modifymenu');
    function family_modifymenu() {

        //this is the main item for the menu
        add_menu_page('Family', //page title
        'Family', //menu title
        'manage_options', //capabilities
        'family_list', //menu slug
        'family_list' //function
        );

        //this is a submenu
        add_submenu_page('family_list', //parent slug
        'Rekapan', //page title
        'Rekap Family', //menu title
        'manage_options', //capability
        'lihat_rekap_family', //menu slug
        'lihat_rekap_family'); //function

        //this submenu is HIDDEN, however, we need to add it anyways
        add_submenu_page(null, //parent slug
        'Update Family', //page title
        'Update', //menu title
        'manage_options', //capability
        'update_rekap_family', //menu slug
        'update_rekap_family'); //function
    }


//  define('ROOTDIR', plugin_dir_path(__FILE__));

    function fam_subscriber_to_uploads() {
        $subscriber = get_role('subscriber');

        if ( ! $subscriber->has_cap('upload_files') ) {
            $subscriber->add_cap('upload_files');
        }
    }

    add_action('admin_init', 'fam_subscriber_to_uploads');

        function fam_input_form(){

                $nama = $_POST["user_name"];
                $email = $_POST["user_email"];
                $gambar = $_POST["async-upload"];
            //insert
                if (isset($_POST['insert'])) {
                global $wpdb;
                $table_name = $wpdb->prefix . 'family_survey';

                    $wpdb->insert(
                        $table_name,
                        array(
                            'nama' => $nama,
                            'email' => $email,
                            'gambar' => $gambar,
                        ),
                        array('%s','%s','%s')
                    );
    }
            ob_start();
            ?>
                <?php if ( is_user_logged_in() ): ?>
                    <p class="form-notice"></p>
                    <form action="" method="post" class="image-form">
                        <?php wp_nonce_field('image-submission'); ?>
                        <p><input type="text" name="user_name" placeholder="Your Name" required></p>
                        <p><input type="email" name="user_email" placeholder="Your Email Address" required></p>
                        <p class="image-notice"></p>
                        <p><input type="file" name="async-upload" class="image-file" accept="image/*" required></p>
                        <input type="hidden" name="image_id">
                        <input type="hidden" name="action" value="image_submission">
                        <div class="image-preview"></div>
                        <hr>
                        <p><input type="submit" name="insert" value="Submit"></p>
                    </form>
                <?php else: ?>
                    <p>Please <a href="<?php echo esc_url( wp_login_url( get_permalink() ) ); ?>">login</a> first to submit your image.</p>
                <?php endif; ?>
            <?php
            $output = ob_get_clean();
            return $output;
        }
        add_shortcode('family_form', 'fam_input_form');


    function fam_load_scripts() {
        wp_enqueue_script('image-form-js', plugin_dir_url( __FILE__ ) . 'js/myfam-public.js', array('jquery'), '0.1.0', true);

        $data = array(
                    'upload_url' => admin_url('async-upload.php'),
                    'ajax_url'   => admin_url('admin-ajax.php'),
                    'nonce'      => wp_create_nonce('media-form')
                );

        wp_localize_script( 'image-form-js', 'su_config', $data );
    }
    add_action('wp_enqueue_scripts', 'fam_load_scripts');

        function fam_image_submission_cb() {
            check_ajax_referer('image-submission');

            $user_name  = filter_var( $_POST['user_name'],FILTER_SANITIZE_STRING );
            $user_email = filter_var( $_POST['user_email'], FILTER_VALIDATE_EMAIL );
            $image_id   = filter_var( $_POST['image_id'], FILTER_VALIDATE_INT );


            if ( ! ( $user_name && $user_email && $image_id ) ) {
                wp_send_json_error( array('msg' => 'Validation failed. Please try again later.') );
            }

            $to      = get_option('davidsaerang@gmail.com');
            $subject = 'New image submission!';
            $message = sprintf(
                            'New image submission from %s (%s). Link: %s',
                            $user_name,
                            $user_email,
                            wp_get_attachment_url( $image_id )
                        );

            $result = wp_mail( $to, $subject, $message );

            if ( $result ) {
                wp_send_json_error( array('msg' => 'Email failed to send. Please try again later.') );

            } else {

                wp_send_json_success( array('msg' => 'Your submission successfully sent.') );



            }


    }


add_action('wp_ajax_image_submission', 'fam_image_submission_cb');