Hibernate version: 2.1.6

multiple dynamic object instantiation is it possible?

Is it possible to write query like the following?

select new User(u.Id, u.FirstName), new Message(m.Id) from User u join u.Message m

Thanks

no, not currently.

Is there any way I can add/patch quickly? The reason I am intersted is hibernate is making unecessary extra queries to retrieve associate objects. For example I have the following mapping

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >

<hibernate-mapping>
<class name="fleetcycle.domain.framework.communication.MessageRecipient"
table="MESSAGE_RECIPIENT">
<id
column="MESSAGE_RECIPIENT_ID"
name="Id"
type="string"
>
<generator class="uuid.hex" />
</id>
<many-to-one
class="fleetcycle.domain.framework.communication.UserMessage"
name="UserMessage"
not-null="true"
outer-join="true"
>
<column name="USER_MESSAGE_ID" />
</many-to-one>
</class>
<class name="fleetcycle.domain.framework.communication.UserMessage"
table="USER_MESSAGE">
<id
column="USER_MESSAGE_ID"
name="Id"
type="string"
>
<generator class="uuid.hex" />
</id>
<many-to-one
class="fleetcycle.domain.framework.security.User"
name="senderUser"
not-null="true"
outer-join="true"
>
<column name="SENDER_USER_ID" />
</many-to-one>
<set inverse="true" name="MessageRecipientSet" lazy="true">
<key column="USER_MESSAGE_ID" />
<one-to-many class="fleetcycle.domain.framework.communication.MessageRecipient" />
</set>
</class>
</hibernate-mapping>


MessageRecipient has many-to-one relation with UserMessage. When I make query "from MessageRecipient" to retrieve all message recipient objects hibernate is not using join query. It's making individual queries to these 2 tables.

I have 4 entries in message_recipient table so i can see total 5 sql queries being made. One for retrieving data from message_recipient table and 4 queries for retreiving user_message.


Hibernate: select messagerec0_.MESSAGE_RECIPIENT_ID as MESSAGE_1_, messagerec0_.USER_MESSAGE_ID as USER_MES7_ from MESSAGE_RECIPIENT messagerec0_
Hibernate: select usermessag0_.USER_MESSAGE_ID as USER_MES1_2_, usermessag0_.SENDER_USER_ID as SENDER_U8_2_, user1_.USER_ID as USER_ID0_, user1_.LOGIN_ID as LOGIN_ID0_, from USER_MESSAGE usermessag0_ left outer join FC_USER user1_ on usermessag0_.SENDER_USER_ID=user1_.USER_ID where usermessag0_.USER_MESSAGE_ID=?
Hibernate: select usermessag0_.USER_MESSAGE_ID as USER_MES1_2_, usermessag0_.SENDER_USER_ID as SENDER_U8_2_, user1_.USER_ID as USER_ID0_, user1_.LOGIN_ID as LOGIN_ID0_, from USER_MESSAGE usermessag0_ left outer join FC_USER user1_ on usermessag0_.SENDER_USER_ID=user1_.USER_ID where usermessag0_.USER_MESSAGE_ID=?
Hibernate: select usermessag0_.USER_MESSAGE_ID as USER_MES1_2_, usermessag0_.SENDER_USER_ID as SENDER_U8_2_, user1_.USER_ID as USER_ID0_, user1_.LOGIN_ID as LOGIN_ID0_, from USER_MESSAGE usermessag0_ left outer join FC_USER user1_ on usermessag0_.SENDER_USER_ID=user1_.USER_ID where usermessag0_.USER_MESSAGE_ID=?
Hibernate: select usermessag0_.USER_MESSAGE_ID as USER_MES1_2_, usermessag0_.SENDER_USER_ID as SENDER_U8_2_, user1_.USER_ID as USER_ID0_, user1_.LOGIN_ID as LOGIN_ID0_, from USER_MESSAGE usermessag0_ left outer join FC_USER user1_ on usermessag0_.SENDER_USER_ID=user1_.USER_ID where usermessag0_.USER_MESSAGE_ID=?
Hibernate: select usermessag0_.USER_MESSAGE_ID as USER_MES1_2_, usermessag0_.SENDER_USER_ID as SENDER_U8_2_, user1_.USER_ID as USER_ID0_, user1_.LOGIN_ID as LOGIN_ID0_, from USER_MESSAGE usermessag0_ left outer join FC_USER user1_ on usermessag0_.SENDER_USER_ID=user1_.USER_ID where usermessag0_.USER_MESSAGE_ID=?


Is there any thing I miss in my mapping? or is it a desired hibernate behavior?

use the "fetch" keyword

add lazy="true" in class in mapping files.