Basic Doctrine 2 one-to-many/many-to-one association setup

one-to-many-to-one.php

<?php

/*
 * This is a basic setup for Doctrine 2 one-to-many/many-to-one associations.
 * 
 * There are many alternative approaches, additions and optimizations possible,
 * but this example is only meant to help people getting started with the concept.
 */

namespace My\Entity;

use Doctrine\ORM\Mapping as ORM;
use Doctrine\Common\Collections\ArrayCollection;

/**
 * @ORM\Entity
 * @ORM\Table( name="person" )
 */
class Person
{

    /**
     * @ORM\Column( type="integer" )
     * @ORM\GeneratedValue( strategy="IDENTITY" )
     * @ORM\Id
     * @var int
     */
    protected $id;

    /**
     * @ORM\Column( type="string" )
     * @var string
     */
    protected $name;

    /**
     * @ORM\OneToMany( targetEntity="My\Entity\Membership", mappedBy="person", orphanRemoval=TRUE )
     * @var \Doctrine\Common\Collections\Collection
     */
    protected $memberships;

    /**
     * Constructor.
     */
    public function __construct()
    {
        $this->memberships = new ArrayCollection();
    }

    /**
     * @return int
     */
    public function getId()
    {
        return $this->id;
    }

    /**
     * @return string
     */
    public function getName()
    {
        return $this->name;
    }

    /**
     * @param  string $name
     * @return \My\Entity\Person
     */
    public function setName( $name )
    {
        $this->name = $name;
        return $this;
    }

    /**
     * @return array
     */
    public function getMemberships()
    {
        return $this->memberships->toArray();
    }

    /**
     * @param  \My\Entity\Group $group
     * @return \My\Entity\Membership|null
     */
    public function getMembershipByGroup( Group $group )
    {
        foreach( $this->memberships as $membership ) {
            if( $membership->getGroup() === $group ) {
                return $membership;
            }
        }
        return null;
    }

    /**
     * @return array
     */
    public function getGroups()
    {
        $groups = $this->memberships->map(
            function( $membership ) {
                return $membership->getGroup();
            }
        );
        return $groups->toArray();
    }

    /**
     * @param  \My\Entity\Group $group
     * @return \My\Entity\Person
     */
    public function removeGroup( Group $group )
    {
        foreach( $this->memberships as $membership ) {
            if( $membership->getGroup() === $group ) {
                $this->memberships->removeElement( $membership );

                // sync other side of one-to-many/many-to-one association
                $group->removePerson( $this );
            }
        }
        return $this;
    }

    /**
     * For internal use, never call directly.
     * 
     * @internal
     * @param  \My\Entity\Membership $membership
     * @return \My\Entity\Person
     */
    public function addMembership( Membership $membership )
    {
        $this->memberships->add( $membership );
        return $this;
    }

}

/**
 * @ORM\Entity
 * @ORM\Table( name="membership" )
 */
class Membership
{

    /**
     * @ORM\Column( type="integer" )
     * @ORM\GeneratedValue( strategy="IDENTITY" )
     * @ORM\Id
     * @var int
     */
    protected $id;

    /**
     * @ORM\Column( type="string" )
     * @var string
     */
    protected $type;

    /**
     * @ORM\ManyToOne( targetEntity="My\Entity\Person", inversedBy="memberships" )
     * @ORM\JoinColumn( name="person_id", referencedColumnName="id", nullable=FALSE )
     * @var \My\Entity\Person
     */
    protected $person;

    /**
     * @ORM\ManyToOne( targetEntity="My\Entity\Group", inversedBy="memberships" )
     * @ORM\JoinColumn( name="group_id", referencedColumnName="id", nullable=FALSE )
     * @var \My\Entity\Group
     */
    protected $group;

    /**
     * Constructor.
     *
     * @param \My\Entity\Person $person
     * @param \My\Entity\Group  $group
     */
    public function __construct( Person $person, Group $group )
    {
        $this->person = $person;
        $this->group  = $group;

        // sync other side of many-to-one associations
        $person->addMembership( $this );
        $group->addMembership( $this );
    }

    /**
     * @return int
     */
    public function getId()
    {
        return $this->id;
    }

    /**
     * @return string
     */
    public function getType()
    {
        return $this->type;
    }

    /**
     * @param  string $type
     * @return \My\Entity\Membership
     */
    public function setType( $type )
    {
        $this->type = $type;
        return $this;
    }

    /**
     * @return \My\Entity\Person
     */
    public function getPerson()
    {
        return $this->person;
    }

    /**
     * @return \My\Entity\Group
     */
    public function getGroup()
    {
        return $this->group;
    }

}

/**
 * @ORM\Entity
 * @ORM\Table( name="group" )
 */
class Group
{

    /**
     * @ORM\Column( type="integer" )
     * @ORM\GeneratedValue( strategy="IDENTITY" )
     * @ORM\Id
     * @var int
     */
    protected $id;

    /**
     * @ORM\Column( type="string" )
     * @var string
     */
    protected $name;

    /**
     * @ORM\OneToMany( targetEntity="My\Entity\Membership", mappedBy="group", orphanRemoval=TRUE )
     * @var \Doctrine\Common\Collections\Collection
     */
    protected $memberships;

    /**
     * Constructor.
     */
    public function __construct()
    {
        $this->memberships = new ArrayCollection();
    }

    /**
     * @return int
     */
    public function getId()
    {
        return $this->id;
    }

    /**
     * @return string
     */
    public function getName()
    {
        return $this->name;
    }

    /**
     * @param  string $name
     * @return \My\Entity\Group
     */
    public function setName( $name )
    {
        $this->name = $name;
        return $this;
    }

    /**
     * @return array
     */
    public function getMemberships()
    {
        return $this->memberships->toArray();
    }

    /**
     * @param  \My\Entity\Person $person
     * @return \My\Entity\Membership|null
     */
    public function getMembershipByPerson( Person $person )
    {
        foreach( $this->memberships as $membership ) {
            if( $membership->getPerson() === $person ) {
                return $membership;
            }
        }
        return null;
    }

    /**
     * @return array
     */
    public function getPeople()
    {
        $people = $this->memberships->map(
            function( $membership ) {
                return $membership->getPerson();
            }
        );
        return $people->toArray();
    }

    /**
     * @param  \My\Entity\Person $person
     * @return \My\Entity\Group
     */
    public function removePerson( Person $person )
    {
        foreach( $this->memberships as $membership ) {
            if( $membership->getPerson() === $person ) {
                $this->memberships->removeElement( $membership );

                // sync other side of one-to-many/many-to-one association
                $person->removeGroup( $this );
            }
        }
        return $this;
    }

    /**
     * For internal use, never call directly.
     * 
     * @internal
     * @param  \My\Entity\Membership $membership
     * @return \My\Entity\Group
     */
    public function addMembership( Membership $membership )
    {
        $this->memberships->add( $membership );
        return $this;
    }

}

/*
 * Using this setup.
 *
 * First person, group and membership:
 */

$person1 = new Person();
$person1->setName( 'John Doe' );

$group1 = new Group();
$group1->setName( 'Anonymous' );

// this will also add membership to person and group:
$membership1 = new Membership( $person1, $group1 );

$membership1->setType( 'follower' );

$em->persist( $person1 );
$em->persist( $group1 );
$em->persist( $membership1 );

$em->flush();

/*
 * Second person, add it to the same group:
 */

$group1 = $em->find( 'My\Entity\Group', 1 );

$person2 = new Person();
$person2->setName( 'Jane Doe' );

// this will also add membership to person and group:
$membership2 = new Membership( $person2, $group1 );

$membership2->setType( 'follower' );

$em->persist( $person2 );
$em->persist( $membership2 );

$em->flush();

/*
 * Change type of membership of second person:
 */

$person2 = $em->find( 'My\Entity\Person', 2 );
$group1  = $em->find( 'My\Entity\Group', 1 );

$membership = $person2->getMembershipByGroup( $group1 );
$membership->setType( 'leader' );

$em->flush();

/*
 * Remove first person from the group:
 */

$person1 = $em->find( 'My\Entity\Person', 1 );
$group1  = $em->find( 'My\Entity\Group', 1 );

// this will also remove person from group, and delete membership from db due to orphan-removal:
$person1->removeGroup( $group1 );

$em->flush();