Odtnhj

I have a Person and Admin entity. One Person can only have one Admin, but I do not need admin all the time. When I list all people with admin associated, doctrine will load all admins from DB. Why is this happening?

In a case of one-to-one association (and in similar cases, e.g. while lazy loading one-to-many association) Doctrine generates so called proxy objects for associated entities. These proxy objects mimics interface of target entity but only triggers actual data loading from database upon access to non-id field.

Because of this in your case when you're fetching list of Person entities - you doesn't get list of Admin entities fetched from database, but receiving list of Admin proxies instead. Unless you will (occasionally or intentionally) try to access some of properties of Admin entity (with exception of its id which can be safely accessed) Doctrine will not try to fetch any Admin information from database.

Consider following simplified setup of A and B entities with one-to-one association:

// A.php

<?php

namespace AppEntity;

use DoctrineORMMapping as ORM;

/**
 * @ORMEntity()
 */
class A

 /**
 * @var integer
 * @ORMColumn(type="integer")
 * @ORMId
 * @ORMGeneratedValue(strategy="AUTO")
 */
 private $id;
 /**
 * @var B
 * @ORMOneToOne(targetEntity="AppEntityB")
 */
 private $b;

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

 /**
 * @return B
 */
 public function getB(): B
 
 return $this->b;
 


// B.php

<?php

namespace AppEntity;

use DoctrineORMMapping as ORM;

/**
 * @ORMEntity()
 */
class B

 /**
 * @var integer
 * @ORMColumn(type="integer")
 * @ORMId
 * @ORMGeneratedValue(strategy="AUTO")
 */
 private $id;
 /**
 * @var string

You can proof that A::$b contain proxy object by either looking into debugger or by using reflection:

$entities = $this->getEntityManager()->getRepository(AppEntityA::class)->findAll();
/** @var AppEntityA $a */
$a = array_shift($entities);
$class = (new ReflectionObject($a->getB()))->getName();

In this case value of $class variable will be Proxies__CG__AppEntityB (Doctrine proxy object for AppEntityB) and not AppEntityB as it would be in a case of normal entity object.