cakephp3有很多关联返回null

Question

我试图在书籍和作者之间建立一个很多关联，但是当从数据库中提取作者的书籍时，他们会在书籍和作者之间建立起来。属性永远不会定义。给我以下错误：

Warning (2): Invalid argument supplied for foreach() [APP/Template\Authors\index.ctp, line 6]

到目前为止我的代码：

的src /型号/ Authors.php

<?php
    class Author extends AppModel
    {
       var $name = 'Author';
       var $hasMany = 'Book';
    }
?>

的src /型号/ Books.php

<?php
class Book extends AppModel
{   var $name = 'Book';
    var $belongsTo = 'Author';
}
?>

SRC /控制器/ BooksController.php

<?php
namespace App\Controller;
use App\Controller\AppController;
class BooksController extends AppController {
   var $name = 'Books';
   function index() {
      $this->Book->recursive = 1;
      $books = $this->Book->find('all');
      $this->set('books', $books);
   }
}
?>

SRC /控制器/ AuthorsController.php

<?php
namespace App\Controller;
use App\Controller\AppController;
class AuthorsController extends AppController {
   var $name = 'Authors';
   function index() {
      $this->Authors->recursive = 2;
      $authors = $this->Authors->find('all');
      $this->set('authors', $authors);
   }
}
?>    

的src /模板/作者/ index.php的

<?php foreach($authors as $author): ?>
    <h2><?php echo $author['Author']['name'] ?></h2>
    <hr />
    <h3>Book(s):</h3>
    <ul>
    <?php foreach($author['Book'] as $book): ?>
        <li><?php echo $book['title'] ?></li>
    <?php endforeach; ?>
    </ul>
<?php endforeach; ?>

数据库作者和书籍表都包含数据，并使用以下迁移创建：

<?php
use Migrations\AbstractMigration;

class CreateAuthors extends AbstractMigration
{
    /**
     * Change Method.
     *
     * More information on this method is available here:
     * http://docs.phinx.org/en/latest/migrations.html#the-change-method
     * @return void
     */
    public function change()
    {
        $table = $this->table('authors');
        $table->addColumn('name', 'text', [
            'default' => null,
            'null' => false,
        ]);
        $table->addColumn('email', 'text', [
            'default' => null,
            'null' => false,
        ]);
        $table->addColumn('website', 'text', [
            'default' => null,
            'null' => false,
        ]);
        $table->create();
    }
}

并且

<?php
use Migrations\AbstractMigration;

class CreateBooks extends AbstractMigration
{
    /**
     * Change Method.
     *
     * More information on this method is available here:
     * http://docs.phinx.org/en/latest/migrations.html#the-change-method
     * @return void
     */
    public function change()
    {
        $table = $this->table('books');
        $table->addColumn('isbn', 'text', [
            'default' => null,
            'null' => false,
        ]);
        $table->addColumn('title', 'text', [
            'default' => null,
            'null' => false,
        ]);
        $table->addColumn('description', 'text', [
            'default' => null,
            'null' => false,
        ]);
        $table->addColumn('author_id', 'string', [
            'default' => null,
            'limit' => 255,
            'null' => false,
        ]);
        $table->create();
    }
}

非常感谢任何帮助。