doctrine2 loads one-to-many associations with fetch mode eager using too many SQL queries

Question

I am loading a list of many entities.
These entities have a one-to-many association to other entities.
I want to load all these other entities in one single SQL quer

Answer 1

According to your link:

You can mark a many-to-one or one-to-one association as fetched temporarily to batch fetch these entities using a WHERE .. IN query

It looks like the current version of Doctrine does not support eager loading on a one-to-many collection, unfortunately.

This page seems to confirm this supposition:

@OneToMany

Required attributes:

targetEntity: FQCN of the referenced target entity. Can be the unqualified class name if both classes are in the same namespace. IMPORTANT: No leading backslash!

Optional attributes:

• cascade: Cascade Option
• orphanRemoval: Boolean that specifies if orphans, inverse OneToOne entities that are not connected to any owning instance, should be removed by Doctrine. Defaults to false.
• mappedBy: This option specifies the property name on the targetEntity that is the owning side of this relation. Its a required attribute for the inverse side of a relationship.

The @OneToMany annotation does not feature a fetch attribute, as opposed to @OneToOne and @ManyToOne.

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Update

I just noticed that you can actually eager fetch the related entities, using an explicit LEFT JOIN in DQL:

SELECT u, a FROM User u
LEFT JOIN u.addresses a

Do use a LEFT JOIN, and not an inner JOIN, or entities with an empty collection (User without any Address) would be omitted from the result set.

Update (2017)

As pointed by GusDeCool and webDEVILopers in the comments, the fetch attribute is now supported on @OneToMany. The above answer is now obsolete.