<?php 
 
use \library\Registry, 
    \library\Book; 
 
include __DIR__ . "/../bootstrap.php"; 
 
if (empty($_POST["book_id"])) { 
    die("No book ID provided"); 
} 
 
if (empty($_POST["author_id"])) { 
    die("No author ID provided"); 
} 
 
/** @var Book $book */ 
$book = Registry::persistenceDriver()->find((int) $_POST["book_id"], new Book()); 
if (!$book) { 
    die("Book ID #" . (int) $_POST["book_id"] . " not found"); 
} 
 
if ($book->hasAuthor($_POST["author_id"])) { 
    die("This book already has this author"); 
} 
 
$book->addAuthor($_POST["author_id"]); 
 
header("Location: book_edit.php?id=" . (int) $_POST["book_id"]);
 
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