Begining to code the Ajax action

wp-pdf-helper.php

@@ -32,16 +32,36 @@ add_action('manage_media_custom_column', 'manage_custom_columns', 10, 2);
 function manage_custom_columns ($column_key, $post_id) {
     if ($column_key == 'wp-pdf-helper') {
         $checked = (get_post_meta($post_id, 'wpdfh.print', true) == '') ? '' : 'checked'; 
-        echo "<input type='checkbox' name='Print' value='always' $checked />";
-        error_log("PHP: \$column_key: $column_key, \$post_id: $post_id, \$is_printable: $is_printable.", 0);
+        echo "<input type='checkbox' class='wpdfh_print_checkbox' name='Print' data-post_id='$post_id' $checked />";
+//        error_log("PHP: \$column_key: $column_key, \$post_id: $post_id, \$is_printable: $is_printable.", 0);
     }
 }
 
 add_action('admin_enqueue_scripts', 'wpdfh_enqueue_admin_scripts');
 function wpdfh_enqueue_admin_scripts() {
     wp_enqueue_style( 'wpdfh-admin', plugin_dir_url( __FILE__ ) . 'assets/wp-pdf-helper-admin.css'  );
+    wp_register_script(
+            'wpdfh-ajax-admin',
+            plugins_url('assets/jquery.ajax.js', __FILE__),
+            array(),
+            false,
+            true
+            );
+    wp_enqueue_script( 'wpdfh-ajax-admin' );
+    wp_localize_script(
+            'wpdfh-ajax-admin',
+            'wpdfh_ajax_object',
+            array( 'ajaxurl' => admin_url( 'admin-ajax.php' ) )
+            );
 }
 
+add_action( "wp_ajax_wpdfh_set_print_metadata", "wpdfh_set_print_metadata" );
+function wpdfh_set_print_metadata(){
+    error_log("PHP: wpdfh_set_print_metadata", 0);
+    wp_send_json_success();
+}
+
+
 if ( ! array_key_exists('print', $_GET)) {
     return;
 }