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JPA Hibernate: How to prevent join on retrieving?

Answer 1

+1 A:

select a from A a ?

also, how have you've mapped your relations? lazy="proxy" and fetch="join"?

Viktor Klang 2010-01-13 14:58:23

setting lazy="proxy" and fetch="join" is global and affects all other queries. This is a single query requirement.

Mohsen 2010-01-13 15:06:16

Use criteria API if you want to specify query custom fetchmodes.

Viktor Klang 2010-01-13 17:34:03

Answer 2

+1 A:

You can specify fetch="select" and lazy="true" in your mapping. Especially if your relations -> are lists.

bertolami 2010-01-13 14:59:32

I have object to object relation (no list: one to one or many to one, where A is many side). setting lazy or fetch is global and affects all other queries. This is a single query requirement.

Mohsen 2010-01-13 15:07:58

if you use the criteria api you can specify the fetch type. I don't know how/if you can do this with hql.

bertolami 2010-01-13 16:11:04

Answer 3

+2 A:

If you have a constructor for A which fills all fields except the ones you don't want to join, you could select like this:

SELECT NEW A(a.x, a.y, a.z) FROM A a

Bob 2010-01-13 15:02:03

is this Hibernate specific feature or JPA's?

Mohsen 2010-01-13 15:06:53

This is a feature of JPA.

Bob 2010-01-13 15:08:20

Thanks for your help, but this way I should add a new constructor for each query which is a nightmare.

Mohsen 2010-01-13 15:21:42

You can create one constructor with all fields, and fill the unwanted fields with NULL.

Bob 2010-01-13 15:34:14

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JPA Hibernate: How to prevent join on retrieving?

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