I have the following entity in hbm.xml file
<class name="Base" table="base">
<id name="id"/>
<list name="ips" cascade="all-delete-orphan" lazy="false" fetch="join">
<cache usage="read-write" include="all" />
<key column="base_id" />
<list-index column="ip_order"/>
<element column="ip" type="string"/>
</list>
</class>
i have one entity Base with two ips string in the collection.
when i make:
session.createCriteria(base.class).list();
the result is two Base object
when i make:
session.createQuery(" from Base").list();
the result is one entity Base.
can someone tell me why i have this situation?
As per your mapping xml Base is one table and ips(IP) is another table.
One Base having two List(ips) means Base table will have one entry in DB(base table).
IP will have two entries in DB (ip table).
Obvisully Base table will have only one entry.
Check this example
I bet there are 2 records in the table for ips.
As you have declare ips being eager fetched, so it will also join fetch the ips when you are creating the criteria to fetch Base.class, causing the "result set" contains 2 records. However, the two "records" are in fact same instance.
The way to solve is simple though, search for use of DISTINCT_ROOT_ENTITY result transformer.
Related
I am using Hibernate 3.2.5. I am getting the above exception while using many-to-one mapping. The training table is having a many to one relation with Department table, i.e. One Depatement is capable of taking more than one training.
The exception is asking me to add insert="false" update="false" in my hbm file. If I add this bit in hbm file, then the code works fine.
Here is the hbm file:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="com.infy.model.Training" table="training">
<id name="Id" type="integer" column="ID">
<generator class="assigned"></generator>
</id>
<property name="trainerName">
<column name="TRAINER_NAME"></column>
</property>
<property name="deptId">
<column name="DEPT_ID"></column>
</property>
<property name="trainingSubject">
<column name="TRAINING_SUBJECT"></column>
</property>
<many-to-one name="departmentDetails" column="DEPT_ID"></many-to-one>
</class>
</hibernate-mapping>
If I change this line to:
<many-to-one name="departmentDetails" column="DEPT_ID" insert="false" update="false"></many-to-one>
Then the code works. I want to know what is the exact reason for adding this.
Regards,
You have mapped the DEPT_ID column twice, here:
<property name="deptId">
<column name="DEPT_ID"></column>
</property>
And here:
<many-to-one name="departmentDetails" column="DEPT_ID"></many-to-one>
When executing a select statement, Hibernate will be fine populating two properties of your object from the same column, however when doing an insert or an update it cannot decide which property to persist in the database.
Why do you need two properties mapped to the same column in the first place? If you need access to the deptId, you can probably remove the deptId property and instead do
training.getDepartmentDetails().getId()
The error message for this scenario is quite clear (you haven't put it here, but I've seen it a few times). The problem is that you've mapped the column DEPT_ID to two different fields in your class.
First, you've mapped it to the property deptId and then to departmentDetails. As you found out, hibernate allows to do this only if one of the mappings is configured to be insert="false" update="false".
The reason is quite simple. If you would change deptId to another id, hibernate would need to change the class that is mapped in departmentDetails, which is quite complicated.
if you need to get the deptId, you can add a getDeptId method on Training that returns departmentDetails.getId(). And don't provide a setDeptId.
If you are using the same column name twice in your mapping file. might be you get mapping Exception
Initial SessionFactory creation failed.org.hibernate.MappingException:
Also if u mark insert=flase and update=false .
if u try to update or insert in records in table or another legacy system try to update these column value. it wouldn't update or insert that filed.
Please check the below link .it will help to find your solutions.
http://www.techienjoy.com/hibernate-insert-update-control.php
Thanks
Sandeep G.
I have the following DB schema :
table a {
id,
state
}
table b {
id,
a_id,
is_valid,
amount
}
I want to have a hibernate mapping where I fetch values from table b only if a.state has a certain value. This is the hibernate mapping i had (used the example from the jBoss Documentation)
<discriminator column="state" type="string"/>
<subclass name="ClassB" discriminator-value="VALUE1">
<join table="b">
<key column="a_id"/>
<property name="amount" column="amount"/>
</join>
</subclass>
When i did this, my xml showed a syntax error stating that a hierarchy must be followed.
Is what I'm doing correct and if not, it would be great if someone could show me the way forward. Thanks.
P.S - more than one entry in table b will have the a_id column. However only one row in b will have the is_valid value set and its enough if i get this row in my POJO
It looks to me like you are mapping a table per subclass with discriminator strategy. This would imply a 1 - 1 row correlation between table a and table b, where the primary key of table b (the subclass) would also be a foreign key into table a.
However, your mapping is slightly odd in that you have
<key column="a_id" />
Typically this should be
<key column="id" />
And there would be no "a_id" column.
However, your db design looks like a one-to-many relationship rather than a subclass relationship.
Without your objects themselves, i can't really say what it is you're trying to do.
Take a look at the hibernate docs on inheritence.
http://docs.jboss.org/hibernate/core/3.6/reference/en-US/html/inheritance.html
I am trying to implement persistence of some Java objects via Hibernate mapping to a MySQL table. When I commit I get a message saying 'Batch update returned unexpected row count from update [0]; actual row count: 0; expected: 1'.
My hypothesis is that the problem is caused from having a long-field in my Java POJO that I want to use as my primary key in the MySQL table. Since I was not able to use datatype LONG as my primary key in MySQL table (ERROR 1170: BLOB/TEXT column 'id' used in key specification without a key length) I concluded from some googling and this post that BIGINT would be the suitable mapping for long. However it is not updating.
My test POJO Personis very simple. It has 3 fields: id (long), firstname (String), lastname (String) with setters and getters, etc.
I do the hibernate mapping in xml (person.hbm.xml) that essentially looks like (minus headings):
<hibernate-mapping>
<class name="hibernatetest.Person" table="hibernatetest">
<id name="id" type="long" column="id" >
<generator class="native"/>
</id>
<property name="firstname">
<column name="firstname" />
</property>
<property name="lastname">
<column name="lastname"/>
</property>
</class>
</hibernate-mapping>
My actual java code snippet that is supposed to save or update the record is simple:
Transaction tr = session.beginTransaction();
Person person = new Person(1,"John","Doe");
session.saveOrUpdate(person);
tr.commit();
And here's that thing, this all works just fine if I change the type of id to an int (Integer) in the Person object and in the MySQL table. However, I do not have that option for the actual objects that I want to persist so the question is; what am I doing wrong or what should I do to get it to work? Thanks.
ADDING Stacktrace:
Hibernate: update hibernatetest set firstname=?, lastname=? where id=?
org.hibernate.StaleStateException: Batch update returned unexpected row count from update [0]; actual row count: 0; expected: 1
at org.hibernate.jdbc.Expectations$BasicExpectation.checkBatched(Expectations.java:81)
at org.hibernate.jdbc.Expectations$BasicExpectation.verifyOutcome(Expectations.java:73)
at org.hibernate.engine.jdbc.batch.internal.NonBatchingBatch.addToBatch(NonBatchingBatch.java:57)
at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:3006)
at org.hibernate.persister.entity.AbstractEntityPersister.updateOrInsert(AbstractEntityPersister.java:2908)
at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:3237)
at org.hibernate.action.internal.EntityUpdateAction.execute(EntityUpdateAction.java:113)
at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:273)
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:265)
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:187)
at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:337)
at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:50)
at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1082)
at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:317)
at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.beforeTransactionCommit(JdbcTransaction.java:101)
at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.commit(AbstractTransactionImpl.java:175)
at com.hibernate.test.TestMain.main(TestMain.java:38)
nested transactions not supported
UPDATE:
OK, I have finally worked it out. I changed the hibernate generator class from 'native' to 'assigned' and now it works as expected. So now the hibernate mapping looks like:
<hibernate-mapping>
<class name="hibernatetest.Person" table="hibernatetest">
<id name="id" type="long" column="id" >
<generator class="assigned"/>
</id>
<property name="firstname">
<column name="firstname" />
</property>
<property name="lastname">
<column name="lastname"/>
</property>
</class>
</hibernate-mapping>
Must admit I did not know the meaning of that parameter (copied from somewhere) and had no idea it could cause this much headache. Found this explanation which was quite useful.
Apparently I do not have enough credentials to answer my own questions so I guess that it will remain open or if someone provides an empty answer, I will accept it. Thanks.
When you use the saveOrUpdate() method hibernate fires the insert query if the id of the object is null and update if it is any other value. I can see the code,
Person person = new Person(1,"John","Doe"); setting the id to 1 and calling the saveOrUpdate() method. I am assuming there are no entries for the id 1 and hence the error is thrown.
To make it work, you need to make the below changes.
Change the Type of id in person to Long from long(The wrapper class so that it can support null).
Write the constructor new Person("John","Doe"); and save that object.
It is not a good Idea to keep the <generator class="assigned"/> for the transactional data. Instead you should be sticking to the native as you were trying first.
I feel this is a cleaner way to solve your initial problem, even though you have found an alternate solution.
Given an entity with a list of components:
class Entity{
Long id;
String name;
List<Component> components = new ArrayList<Component>();
}
class Component{ Object value; }
Configuration:
<hibernate-mapping>
<class name="Entity" table="entity">
<id name="id" access="field" column="id"/>
<property name="name" access="field" unique="true"/>
<list name="components" access="field" table="COMPONENTS" lazy="true">
<key column="id"/>
<list-index column="idx"/>
<composite-element class="Component">
<property name="value" access="field"/>
</composite-element>
</list>
</class>
</hibernate-mapping>
Is it possible to update one component from the list with HQL statement like
update Entity e set e.components[:index].value = :value where e.name = :name
that does not work?
Alternatively, is it possible to configure lazy loading of the list of components in a way that the first access:
entity.components.get(0).value = "..";
does not load the whole list?
Edit:
The lazy="extra" configuration does work for select (loads only the component to update), but it will not update the changed component.
You can't update a single collection element via HQL.
From the 13.4. DML-style operations chapter:
There can only be a single entity named in the from-clause.
No joins, either implicit or explicit, can be specified in a bulk HQL query.
Since your collection element is not an entity, it's not addressable from within bulk update. Technically speaking, non-entity collection elements are not addressable in general; indexed collections or sets with elements having natural ids being the only exceptions.
While it is possible to lazy-load collection elements few at a time (though it doesn't really make sense in this case unless you know ahead of time that you'll only be looking at Nth element since batch size is not easily changeable at runtime), it's not going to help because entire collection will be loaded anyway when you try to update it.
Selecting a single collection element is possible for indexed collection (not part of your question, but I wanted to clarify on this based on KLE answer and your comments):
select c
from Entity e join e.components c
where index(c) = :index
I have an entity that I want to persist through Hibernate (3.2)
The EntityBean has a column that indicates how another value of the entity bean should be unmarshalled:
<class name="ServiceAttributeValue" table="service_attribute_value">
<cache usage="nonstrict-read-write"/>
<id name="id" column="id" type="int-long">
<generator class="native"/>
</id>
<property name="serviceAttribute" type="service-attribute" column="service_attribute" not-null="true" />
<!-- order is important here -->
<property name="value" type="attribute-value" not-null="true">
<column name="service_attribute" />
<column name="id_value"/>
<column name="enum_value"/>
<column name="string_value"/>
<column name="int_value"/>
<column name="boolean_value"/>
<column name="double_value"/>
</property>
</class>
The "service_attribute" column indicates which of the columns for the "value" property to look at when it unmarshalls the value and, more importantly, exactly what Type the value should be, for example the class of the Enum if the enum_value is to be read, or the type of Bean if the the id_value is to be read.
The value property uses a custom CompositeUserType to do the unmarshalling and within this I wish to reference the service_attribute column (although not write to it), however when I try to do this I get the following error:
org.hibernate.MappingException: Repeated column in mapping for entity: com.precurse.apps.rank.model.service.ServiceAttributeValue column: service_attribute (should be mapped with insert="false" update="false")
However within the definition of the composite property these xml attributes are not defined (only within a normal property).
Does anyone know of a way of overcoming this, or if there is a better solution to this propblem.
If you need any more information please let me know,
Cheers
Simon
I had a similar problem and changing the case of one column solved the problem. Could give a try!
e.g., one column could be service_attribute other Service_Attribute.
You can try this. Instead of mapping both values as property on the same table, map one of the property using join to itself and keep the other property as the way it is. This case you will be able to access the same property in both places. Just remember to name the property as different name.
<join table="service_attribute_value">
<key column = "id" />
<property name="serviceAttribute" type="service-attribute" column="service_attribute" not-null="true" />
</join>
<!-- order is important here -->
<property name="value" type="attribute-value" not-null="true">
<column name="service_attribute" />
<column name="id_value"/>
<column name="enum_value"/>
<column name="string_value"/>
<column name="int_value"/>
<column name="boolean_value"/>
<column name="double_value"/>
</property>
based on your description, it seems like what you want to do is creating different subclasses based on the service_attribute. Instead of trying to achieve repeated column mapping which is not allow in hibernate, you can take a look hibernate inheritance mapping.
I Think I found a solution albeit not a very elegant one.
in the
public Object nullSafeGet(ResultSet rs, String[] names, SessionImplementor session, Object owner)
throws HibernateException, SQLException {
method of the CompositeUserType the "owner" argument passed to the method contains the id of the object who's service_attribute I want to access.
Annoyingly the actual serviceAttribute of the owner is not accessable or has not been set at this stage (I played around with the ordering of the elements in the hbm.xml config, in case this was an ordering thing, but unfortunatly still no joy), so I can't simply access it.
Anyway the id of the owner object is set, so I then used the session argument to run a HQL query based on the id to access the serviceAttribute which I then used to correctly unmarshall the value property.
The drawback of this solution is that it requires a HQL query as an overhead to the unmarshalling process, although its within the same session, its still not optimal.
If anyone has any ideas for a better solution I'd be very grateful.
Cheers