Develop Reference

Can Hibernate automatically select after insert?

I am inserting an object into a table using Hibernate saveOrUpdate(object). This object does have an automatically generated ID field and also a 'createdDate' field that is set by the database upon insert. After the insert, the ID field in the java object has the new generated value, but the 'createdDate' field is still null.
Is there a way (configuration or setting or parm) that can tell Hibernate to select the new row automatically after the insert is done, so that the Java object in memory is completely filled out? After the user 'saves' the object the webpage stays open on this object for the user to edit more fields (that are only available after the initial insert), so I want to show these generated fields ( ID, createdDate ) to the user.
** EDIT **
Due to an answer, I'm adding the HBM.XML file for the object:
<hibernate-mapping>
<class name="MyObject" table="MyObject">
<id name="objectId" type="java.lang.Integer">
<column name="Object_ID" />
<generator class="identity" />
</id>
. . . other attributes . . .
<property name="createdDate" type="timestamp" update="false" insert="false">
<column name="Created_Date" not-null="true" />
</property>
</class>
</hibernate-mapping>

Annotate the property with #Generated
#Generated(GenerationTime.INSERT)
private Date creationDate;
Note that this will have a cost. You could simply generate the creationDate in the code, and not in the database (using a listener or a JPA #PrePersist annotation).

How to map 2 identical tables in Hibernate hbm file?

I have tables like Trade_PAC_UNADJUSTED and Trade_PAC_ADJUSTED. Similary for other regions .The table structure is same and they all belong to the same schema. How do i map these tables. I don't want to duplicate the properties of the class entries in .hbm file. Also my POJO class will be same for all of them.
Please help.
Is it possible to have something like this :
<class name="com.Bean" table="TRADE" entity-name="TRADE">
<discriminator type="string">
<column name="PROCESSING_LOCATION" />
</discriminator>
<property name="..........></property>
<subclass name ="com.Bean" discriminator-value="PAC">
<discriminator type="integer">
<column name="RUN_ID" />
</discriminator>
<subclass name ="com.Bean" discriminator-value="1" entity-name="TRADE_PAC_UADJUSTED"/>
<subclass name ="com.Bean" discriminator-value="2,3,4,5,6,7,8,9" entity-name="TRADE_PAC_ADJUSTED"/>
</subclass>
</class>
But there is no way i can pass the table name within subclass ?

If you create a new POJO object and ask Hibernate to save it, how will it know which of your tables it should insert into? You will need something in your POJO to tell it which way to go.
You might be able to do this using a Hibernate "discriminator" to treat this as an inheritance scenario.

Hibernate: How do I join a table with itself?

I have a problem joining a table. Actually I'm really lost on how to do it. I have this Hibernate table mapping.
<class name="Technology" table="TECHNOLOGIES">
<id name="technoId">
<column name="techno_id" />
<generator class="identity" />
</id>
<property name="description" type="java.lang.String">
<column name="description" />
</property>
<many-to-one name="parent" class="Technology" />
</class>
The column parent is related with the same table. An example of the table so you can understand me.
techno_id | description | parent
1------------"Java"----------null
2------------"Hibernate"------1
3------------"HQL"------------2
4------------".NET"----------null
5------------"NHibernate"----4
That's basically an example of the table, it doesn't have real data, it's just an example.
What I want to do is, in a method that receives a techno_id, run with Criteria or HQL, and that brings me a List of results with the children id's too.
For example, if I send to the method the "1" techno_id, it should bring me a List with the ids "1, 2, 3".
I hope I was as clear as possible and you can help me.
Thanks, and sorry for my english jaja.

You need to use join tag with inverse
<join table ="Technologies" inverse ="true" optional = "false">
<key column = "techno_id"/>
<many-to-one name="parent" class="Technology" />
</join>

There are two ways of doing it.
By Criteria :
1. For specific level fetching : e.g 3 level fetching(As per your example)
public Technology getAllChildrenTechnology(long parentID){
Crtieria criteria = session.createCriteria(Technology.class);
criteria.add(Restriction.eq("id",parentID));
criteria.setFetchMode("parent",FetchMode.JOIN);
criteria.setFetchMode("parent.parent",FetchMode.JOIN);
criteria.setResultTransformer(criteria.DISTINCT_ROOT_PROPERTY);
Technology techno = (Technology)criteria.uniqueResult();
return techno;
}
2. For N level Fetching : You need to create n level for loop.(Recursive loop using above).
By Lazy :
There is a feature in hibernate that allow us to fetch some joins without using criteria.
<many-to-one name="parent" class="Technology" lazy="false"/>

I believe this question is not really Hibernate specific. Even you are writing SQL, you have no easy way to get a node with all its descendant, without special handling in design.
Easiest way is to have each Technology contains List of child technologies (Bidirectional relationship). Then traverse Technology's children recursively.
If you need quick retrieval from persistence storage, you have to cater that in your design. One way is as described in an answer I wrote before for a similar question. https://stackoverflow.com/a/7524077/395202
This method is not that Hibernate friendly anyway (It still works, just need extra attentions)

Hibernate set mapped to a 'sql select' table

Good day,
I have a hibernate mapping which goes something like this
<class name="Person">
<id name="id" type="long" column="person_id" unsaved-value="null">
<generator class="sequence">
<param name="sequence">person_id_seq</param>
</generator>
</id>
...
<set name="thinCollection" table="(select person_id, person_property from some_other_table where another_property = 'something')" fetch="subselect" lazy="false">
<key column="person_id"/>
<element column="person_property" type="long"/>
</set>
...
</class>
Now my problem is, when a Person object gets flushed, it tries to execute a Collection Remove Action against Person#thinCollection, which fails because it's trying to execute delete from (select person_id, person_property from some_other_table where another_property = 'something').
Thus in line with that, how do I stop Hibernate from executing such actions (as well as update and inserts) ?
Thanks

I believe you want to use a subselect for your query, thus rendering it readonly.
http://docs.jboss.org/hibernate/stable/core/reference/en/html/mapping.html

Wouldn't
cascade="none"
Do the trick ?
[EDIT] Oups, thought it was NHibernate :P Well, I hope it would still work :)

What I currently did to solve this is to create my own persister (which is a subclass of BasicCollectionPersister) which never does an insertion/update/deletion.
But I am not sure if this is the best way to go about this or if could simply just add a magic mapping attribute to prevent the insertion/update/deletion.
[EDIT]
I found it hard to map my Set to a subselect so I used my own custom BasicCollectionPersister instead. I overriden #isRowDeleteEnabled() and #isRowInsertEnabled() to both always return false. And I overriden #doUpdateRows(..) to always return 0.

Lazy One-to-One using Proxy not working

I've got a one-to-one relation between a dealer and a seller which should be lazy using a proxy. For the side on which the foreign key is defined (the seller, references the dealer), this works fine. But it doesn't work from the other side - the seller is always loaded eagerly. I set constrained="true" as described in "Some explanations on lazy loading", but that didn't help.
Following is the used mapping:
<class name="Role" table="PER_PERSROLE" abstract="true">
<id column="OID" type="long">
<generator class="native" />
</id>
<discriminator column="SUBTYPE" type="string" />
</class>
<subclass name="Dealer" extends="Role" discriminator-value="DEAL">
<property name="gpNr" column="GP_NR" type="string" />
<one-to-one name="seller" property-ref="dealer" lazy="proxy" constrained="true"
outer-join="false" />
</subclass>
<subclass name="Seller" extends="Role" discriminator-value="SELL">
<many-to-one name="dealer" column="SELLER_DEALEROID" lazy="proxy"
outer-join="false" />
</subclass>
Is it a problem that both classes reside in one table? I see that strictly speaking the relation isn't constrained on the database (it can't using this model), but the domain model always needs both entities and the application ensures this.

I think that the page you linked to explained it best, though I am not sure why it recommends setting constrained="true". If you think about it on the database level, Hibernate can't tell if the given property (the Dealer's seller) should be null or not without hitting the database (it needs to do a SELECT ... WHERE OID=:sellerOrDealerId to see if any rows are returned). And while it's hitting the database, it might as well fetch the rest of the row. From the other side of the association (Seller's dealer), there are no such problems since it has already fetched the row (and thus the SELLER_DEALEROID column).
I did encounter something similar to this once and was able to solve it by making the association non-optional (err, non-nullable)

I'm guessing you are loading session.get(id)? Have you tried load the instance using an HQL query? That will allow you to specify in the query which relationships to eager or lazy load.
HTH