query entities contained in a composite entity in doctrine2 - symfony

Question

I have a Friendship class that contains a $user and a $friend. I'd like to get a list of a all friends for a user. I'm unsure on how to create a query builder to do this.
Here's my yml.
Acme\Project\Domain\User\Entity\Friendship:
type: entity
table: friendships
id:
user:
associationKey: true
friend:
associationKey: true
fields:
createdAt:
type: datetimetz
column: created_at
manyToOne:
user:
targetEntity: Acme\Project\Domain\User\Entity\User
joinColumn:
name: user_id
referencedColumnName: id
onDelete: CASCADE
friend:
targetEntity: Acme\Project\Domain\User\Entity\User
joinColumn:
name: friend_id
referencedColumnName: id
onDelete: CASCADE
I've tried this
$qb->select('f.friend')
->from(Friendship::CLASS, 'f')
->where('IDENTITY(f.user) = :user_id')
->setParameter('user_id', $user->getId());
But get the following error.
[Semantical Error] line 0, col 9 near 'friend FROM Acme\\Project\\Domain\\User\\Entity\\Friendship': Error: Invalid PathExpression. Must be a StateFieldPathExpression.
I'm almost certain it's because the select portion contains a ".".

Answer 1

OK you have an error "must be a statefield expression" because as you say there is a dot in your select, you select a member of your root variable 'f'.
But in your case I think your mapping is wrond and that's why you encounter difficulties to write your query.
I think you shouldn't have a Friendship class, and some ManyToOne associations.
But only a ManyToMany association in User class with self-referencing
Here from the official doc :
many-to-many-self-referencing
I quote :
You can even have a self-referencing many-to-many association. A
common scenario is where a User has friends and the target entity of
that relationship is a User so it is self referencing. In this
example it is bidirectional so User has a field named $friendsWithMe
and $myFriends.
You have to translate the following mapping with annotations, to mapping with yml in your case :
<?php
/** #Entity **/
class User
{
// ...
/**
* #ManyToMany(targetEntity="User", mappedBy="myFriends")
**/
private $friendsWithMe;
/**
* #ManyToMany(targetEntity="User", inversedBy="friendsWithMe")
* #JoinTable(name="friends",
* joinColumns={#JoinColumn(name="user_id", referencedColumnName="id")},
* inverseJoinColumns={#JoinColumn(name="friend_user_id", referencedColumnName="id")}
* )
**/
private $myFriends;
public function __construct() {
$this->friendsWithMe = new \Doctrine\Common\Collections\ArrayCollection();
$this->myFriends = new \Doctrine\Common\Collections\ArrayCollection();
}
// ...
}
And the query :
$qb->select('u')
->from(User::CLASS, 'u')
->join('u.friendsWithMe', 'friendWithMe')
->where('IDENTITY(friendWithMe) = :user_id')
->setParameter('user_id', $user->getId());