php – 问题理解关系映射在原则2

我正在阅读官方文档和大量线程,但仍然找不到我的情况的解决方案.我的情况非常基本.我有2个实体：他们的评论和关键字.一个评论可以有很多关键字,但每个关键字只能用于一个评论.关键字在关键字表中不是唯一的.所以我决定这是一对多关系.表结构简单如下：

关键字

id          int(11)
comment_id  int(11)
text        varchar(30)

注释

id      int(11)
text    text

这是我如何映射他们：

/**
 *  @Entity
 *  @Table(name="comments")
 **/
class Comments
{
    /** @Id @Column(type="integer") */
    private $id;
    /** @Column(type="text") */
    private $text;

    /**
     * @OneToMany(targetEntity="keywords",mappedBy="comment_id")
     */
    private $keywords;

    public function getText(){return $this->text;}
    public function getId(){return $this->id;}
    public function getKeywords(){return $this->keywords;}
}
/**
 *  @Entity
 *  @Table(name="keywords")
 */

class Keywords
{
    /** @Id @Column(type="integer") */
    private $id;

    private $text;

    public function getText(){return $this->text;}
    public function getId(){return $this->id;}
}

以及如何使用它是这样的：

$comments = $this->em->getRepository('comments' )->findAll();
foreach($comments as $comment){
    foreach($comment->getKeywords() as $keyword){
        $keyword->getText();
    }
}

并得到这个错误：

Notice: Undefined index: comment_id in C:web_includesdoctrineORMPersistersBasicEntityPersister.php on line 1096
Notice: Trying to get property of non-object in C:web_includesdoctrineORMPersistersBasicEntityPersister.php on line 1098
Warning: Invalid argument supplied for foreach() in C:web_includesdoctrineORMPersistersBasicEntityPersister.php on line 1098
Notice: Undefined index: comment_id in C:web_includesdoctrineORMPersistentCollection.php on line 168
Fatal error: Call to a member function setValue() on a non-object in C:web_includesdoctrineORMPersistentCollection.php on line 169

哪里不对？应该在哪里定义comment_id？我的映射是否正确？我真的很困难,需要帮助,所以请任何建议是非常欢迎的.

/**
 *  @Entity
 *  @Table(name="comments")
 **/
class Comments
{
    /** @Id @Column(type="integer") */
    private $id;
    /** @Column(type="text") */
    private $text;

    /**
     * @OneToMany(targetEntity="keywords",mappedBy="comment")
     */
    private $keywords;

    public function getText(){return $this->text;}
    public function getId(){return $this->id;}
    public function getKeywords(){return $this->keywords;}
}

/**
 *  @Entity
 *  @Table(name="keywords")
 */
class Keywords
{
    /** @Id @Column(type="integer") */
    private $id;

    /**
     * @ManyToOne(targetEntity="Comments",inversedBy="keywords")
     */
    private $comment;

    /**
     * @Column(type="text") */
    private $text;

    public function getText(){return $this->text;}
    public function getId(){return $this->id;}
}

CREATE TABLE comments (id INT NOT NULL,text LONGTEXT NOT NULL,PRIMARY KEY(id)) ENGINE = InnoDB;
CREATE TABLE keywords (id INT NOT NULL,comment_id INT DEFAULT NULL,PRIMARY KEY(id)) ENGINE = InnoDB;
ALTER TABLE keywords ADD FOREIGN KEY (comment_id) REFERENCES comments(id);