How to join 3 tables in Symfony 3

Question

Here is my Formation class:

class Formation
{
/**
 * @var int
 *
 * @ORM\Column(name="id", type="integer")
 * @ORM\Id
 * @ORM\GeneratedValue(strategy="AUTO")
 */
private $id;

/**
 * @var string
 *
 * @ORM\Column(name="nom", type="string", length=150, unique=true)
 */
private $nom;

/**
 * @var string
 *
 * @ORM\Column(name="description", type="text")
 */
private $description;

/**
 * @var string
 *
 * @ORM\Column(name="duree", type="string", length=100)
 */
private $duree;

/**
 * @var string
 *
 * @ORM\Column(name="difficulte", type="string", length=100)
 */
private $difficulte;

/**
 * @var string
 *
 * @ORM\Column(name="prerequis", type="text")
 */
private $prerequis;

  /**
 * @var bool
 *
 * @ORM\Column(name="is_active", type="boolean" , options={"default":false})
 */
private $is_active;

 /**
 * @ORM\ManyToOne(targetEntity="Category", inversedBy="formations")
 * @ORM\JoinColumn(name="category_id", referencedColumnName="id")
 */
private $category;

/**
* @ORM\ManyToMany(targetEntity="Formatteur", mappedBy="formations")
*/
 private $formatteurs;


 //getter & setter ...

}

Here is my Formatteur class:

class Formatteur
{
/**
 * @var int
 *
 * @ORM\Column(name="id", type="integer")
 * @ORM\Id
 * @ORM\GeneratedValue(strategy="AUTO")
 */
private $id;

/**
 * @var string
 *
 * @ORM\Column(name="nom", type="string", length=255)
 */
private $nom;


/**
 * @var string
 *
 * @ORM\Column(name="prenom", type="string", length=100)
 */
private $prenom;


/**
 * @var string
 *
 * @ORM\Column(name="bio", type="string", length=100)
 */
private $bio;


/**
 * @var string
 *
 * @ORM\Column(name="email", type="string", length=255, unique=true)
 */
private $email;

/**
 * @var string
 *
 * @ORM\Column(name="specialite", type="string", length=100)
 */
private $specialite;




/**
 * @var int
 *
 * @ORM\Column(name="Age", type="integer")
 */
private $age;


 /**
 * @var bool
 *
 * @ORM\Column(name="is_active", type="boolean" , options={"default":false})
 */
private $is_active;



 /**
 * @ORM\ManyToMany(targetEntity="Formation", inversedBy="formatteurs")
 * @ORM\JoinTable(name="formation_formatteur")
 */
 private $formations;

 //getter & setter ...

 }

• A Formateur can make many Formations.
• Formations can be created by several Formateurs.
• I have 3 tables: formation, formateur and formation_formateur.

I want to write a query that returns all information from three tables. How do I do that?

Here is my try:

$query = $this->getEntityManager()->createQuery("SELECT FR,FN,T FROM 
ElearingBundle:Formation FN INNER JOIN ElearingBundle:Formatteur FR WITH 
FR.id=T.formateur INNER JOIN formation_formateur T WITH FN.id=I.formation");

Answer 1

I saw your entites definition you have a ManyToMany relation between Formation and Formatteur to get all information from these entities you can write below DQL.

SELECT FN,FR 
FROM ElearingBundle:Formation FN 
INNER JOIN FN.formatteurs FR

Note: i have user FQN for only ElearingBundle:Formation and no other entity and in join part i have used a property defined in Formation because doctrine itself identify the relation type and will do the join part like you don't have to specify the table names in DQL.

$query = $this->getEntityManager()
              ->createQuery("SELECT FN,FR 
                             FROM ElearingBundle:Formation FN 
                             INNER JOIN FN.formatteurs FR");

Above DQL will generate SQL similar like below

SELECT FN.*,FR.*
FROM formation FN
JOIN formation_formateur FF ON FF.formation_id = FN.id
JOIN formateur FR ON FF.formateur_id = FR.id

See my other related answers also

Query on a many-to-many relationship using Doctrine with Symfony2

How does inner join work on a many-to-many relationship using Doctrine and Symfony2