Doctrine2, ManyToMany relation => SQLSTATE[42000]: Syntax error or access violation - php

Question

I am using Doctrine2 in my project and I have defined following entities:
namespace Model;
/**
* #Entity()
* #Table(name="author")
**/
class Author {
/**
* #Id
* #GeneratedValue
* #Column(type="integer")
**/
private $id;
/** #Column(type="string") **/
private $firstName;
/** #Column(type="string") **/
private $lastName;
/** #Column(type="string", nullable=true) **/
private $titleBefore;
/** #Column(type="string", nullable=true) **/
private $titleAfter;
/** #ManyToMany(targetEntity="Article", mappedBy="authors") **/
private $articles;
public function __construct() {
$this->articles = new \Doctrine\Common\Collections\ArrayCollection();
}
public function getId() {
return $this->id;
}
public function getTitleBefore() {
return $this->titleBefore;
}
public function setTitleBefore($titleBefore) {
$this->titleBefore = $titleBefore;
}
public function getTitleAfter() {
return $this->titleAfter;
}
public function setTitleAfter($titleAfter) {
$this->titleAfter = $titleAfter;
}
public function getLastName() {
return $this->lastName;
}
public function setLastName($lastName) {
$this->lastName = $lastName;
}
public function getFirstName() {
return $this->firstName;
}
public function setFirstName($firstName) {
$this->firstName = $firstName;
}
public function getArticles() {
return $this->articles;
}
public function addArticle($article) {
$this->articles->add($article);
}
}
and
namespace Model;
/**
* #Entity()
* #Table(name="article")
**/
class Article {
/**
* #Id
* #GeneratedValue
* #Column(type="integer")
**/
private $id;
/** #Column(type="string") **/
private $name;
/** #OneToOne(targetEntity="Publication") **/
private $publication;
/**
* #ManyToMany(targetEntity="Author", mappedBy="articles")
*/
private $authors;
public function __construct() {
$this->authors = new \Doctrine\Common\Collections\ArrayCollection();
}
public function getId() {
return $this->id;
}
public function getName() {
return $this->name;
}
public function setName($name) {
$this->name = $name;
}
public function getPublication() {
return $this->publication;
}
public function setPublication($publication) {
$this->publication = $publication;
}
public function getAuthors() {
return $this->authors;
}
public function addAuthor($author) {
$this->authors->add($author);
$author->addArticle($this);
}
public function setAuthors($authors) {
$this->authors = $authors;
}
}
It looks like, that relation author<->article works nicely. Although I encountered a problem. When I try to acces authors in Smarty template like this: {foreach from=$article->getAuthors() item=author}, following exception is thrown:
Fatal error: Uncaught PDOException: SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ON' at line 1 in /code/vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOConnection.php:104 Stack trace:
#0 /code/vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOConnection.php(104): PDO->query('SELECT t0.id AS...')
#1 /code/vendor/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(852): Doctrine\DBAL\Driver\PDOConnection->query('SELECT t0.id AS...')
#2 /code/vendor/doctrine/orm/lib/Doctrine/ORM/Persisters/Entity/BasicEntityPersister.php(1030): Doctrine\DBAL\Connection->executeQuery('SELECT t0.id AS...', Array, Array)
#3 /code/vendor/doctrine/orm/lib/Doctrine/ORM/Persisters/Entity/BasicEntityPersister.php(954): Doctrine\ORM\Persisters\Entity\BasicEntityPersister->getManyToManyStatement(Array, Object(Model\Article))
#4 /code/vendor/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php(2839): Doctrine\ORM\Persiste in /code/vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/AbstractMySQLDriver.php on line 90
I already spent a day on this, trying to find out what went wrong. I was suspicious, that I might use a reserved MySQL word, but I didn't find any in my variables.
I finally managed to obtain complete query log until I got the exception. It looks like, the most interesting query is not present
mysqld, Version: 5.7.20 (MySQL Community Server (GPL)). started with:
Tcp port: 3306 Unix socket: /var/run/mysqld/mysqld.sock
Time Id Command Argument
2017-11-25T23:46:52.327597Z 10 Connect user#articlerepository_php_1.articlerepository_default on article_repository using TCP/IP
2017-11-25T23:46:52.334083Z 10 Query SELECT t0.id AS id_1, t0.firstName AS firstName_2, t0.lastName AS lastName_3, t0.titleBefore AS titleBefore_4, t0.titleAfter AS titleAfter_5 FROM author t0
2017-11-25T23:46:52.342077Z 10 Query SELECT t0.id AS id_1, t0.name AS name_2, t0.publication_id AS publication_id_3 FROM article t0
2017-11-25T23:46:52.348058Z 10 Quit

Answer 1

Looks like I had a mismatch in my ManyToMany relationship. Here are the steps I took to fix this:
I dropped current schema by running bin/doctrine orm:schema-tool:drop --force
Validated current entities with running bin/doctrine orm:validate several times and made changes in entities, until it went through without errors
Generated new schema: bin/doctrine orm:schema-tool:update --force --dump-sql
Correct relationship looks like this:
class Author {
/**
* #ManyToMany(targetEntity="Article", inversedBy="authors")
* #JoinTable(name="authors_articles")
**/
private $articles;
}
class Article {
/**
* #ManyToMany(targetEntity="Author", mappedBy="articles")
*/
private $authors;
}
`