Does a one-to-manyrelationship have to be bidirectional?

sid · **Posted:** Tue Oct 07, 2003 9:53 am

I have been trying to get a simple one-to-many relationship to work. I have a Vendor that can have many contacts. So when I do Vendor.save() it should automatically persist the multiple contacts.

Firstly is this possible? Do I have to use bidirectional? Please advise.

Below are my mappings for vendor and contact respectively:

Code:

<?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="com.poc.Vendor" table="TEST_VENDOR">
       <id name="vendorID" column="VENDORID">
           <generator class="foreign">
            <param name="property">address</param>
           </generator>
        </id>
        <property name="name" column="VENDORNAME"/>
        <bag name="contacts" cascade="all">
           <key column="VENDORID"/>
           <one-to-many class="com.poc.Contact"/>
          </bag>
    </class>
</hibernate-mapping>

Code:

<?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="com.poc.Contact" table="TEST_CONTACT">
        <id name="contactID" column="CONTACTID">
           <generator class="assigned"/>
        </id>
        <property name="name" column="CONTACTNAME"/>
        <property name="phone" column="CONTACTPHONE"/>
    </class>
</hibernate-mapping>

christian · **Posted:** Tue Oct 07, 2003 9:55 am

Your mapping is good, what is the problem? Have you read the Hibernate reference documentation, chapter "Parent/child relationship"?

sid · **Posted:** Tue Oct 07, 2003 10:07 am

Below is the error that I get when I am trying to persist a Vendor with multiple contacts:

Quote:

INFO: Use scrollable result sets: false
Oct 7, 2003 10:03:02 AM net.sf.hibernate.impl.SessionFactoryImpl <init>
INFO: JDBC 2 max batch size: 15
Oct 7, 2003 10:03:04 AM net.sf.hibernate.impl.SessionFactoryObjectFactory addInstance
INFO: no JDNI name configured
Oct 7, 2003 10:03:04 AM net.sf.hibernate.impl.SessionFactoryImpl <init>
INFO: Query language substitutions: {}
<Oct 7, 2003 10:03:04 AM EDT> <Error> <HTTP> <BEA-101017> <[ServletContext(id=1073441,name=poc,context-path=/p
java.lang.NoClassDefFoundError: org/odmg/DCollection
at java.lang.ClassLoader.defineClass0(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:502)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:123)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:250)
at java.net.URLClassLoader.access$100(URLClassLoader.java:54)
at java.net.URLClassLoader$1.run(URLClassLoader.java:193)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:186)
at java.lang.ClassLoader.loadClass(ClassLoader.java:299)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:265)
at java.lang.ClassLoader.loadClass(ClassLoader.java:255)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:315)
at java.lang.ClassLoader.defineClass0(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:502)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:123)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:250)
at java.net.URLClassLoader.access$100(URLClassLoader.java:54)
at java.net.URLClassLoader$1.run(URLClassLoader.java:193)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:186)
at java.lang.ClassLoader.loadClass(ClassLoader.java:299)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:265)
at java.lang.ClassLoader.loadClass(ClassLoader.java:255)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:315)
at net.sf.hibernate.type.BagType.wrap(BagType.java:31)
at net.sf.hibernate.impl.SessionImpl.wrap(SessionImpl.java:2519)
at net.sf.hibernate.impl.SessionImpl.wrap(SessionImpl.java:2459)
at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:708)
at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:605)
at com.poc.BaseDAO.addVendor(BaseDAO.java:61)
at jsp_servlet.__page5._jspService(__page5.java:196)
at weblogic.servlet.jsp.JspBase.service(JspBase.java:33)
at weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run(ServletStubImpl.java:1053)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:387)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:431)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:305)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.jav
at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:317)
at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:118)
at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:3622)
at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2569)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:197)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:170)

Also here is the code for saving vendor:

Code:

public void configure() throws HibernateException {
      //Properties hProp = new Properties();
      //hProp.put("hibernate.connection.driver_class","oracle.jdbc.driver.OracleDriver");
      //hProp.put("hibernate.connection.url","jdbc:oracle:thin:@localhost:1521:JONE");
      //hProp.put("hibernate.connection.username","ep10");
      //hProp.put("hibernate.connection.password","ep10");
      //hProp.put("hibernate.dialect","net.sf.hibernate.dialect.Oracle9Dialect");
      
      sessionFactory =
         new Configuration()
            .addClass(Vendor.class)
            .addClass(Contact.class)
            .buildSessionFactory();
   }

Code:

public boolean addVendor(Vendor vendor) throws HibernateException {
      boolean result = false;

      Session session = sessionFactory.openSession();

      try {
         session.save(vendor);
         session.flush();
         result = true;
         session.connection().commit();
         session.close();
         
      } catch (HibernateException he) {
         result = false;
         throw he;
      } catch (SQLException sqe){
         result = false;
      }
      return result;
   }

christian · **Posted:** Tue Oct 07, 2003 10:09 am

Well, a "Class not found" error would suggest a class is not found by the classloader. In your case, you didn't copy the odmg.jar from the distribution into your library directory. Please read the Quickstart Tutorial in the Hibernate examples or check the "VERSIONS" file in the lib/ directory.

sid · **Posted:** Tue Oct 07, 2003 10:32 am

Following your advise I no longer get the "Class not found" error. In fact I get no errors but the contacts do not get persisted in the Database.

Do I have to explicitly call Contacts.save()?

Below is the code in the JSP for calling the addVendor method:

Code:

//Vendor Attributes
   String vendorID = "222";
   String vendorName = "testing!!!!";

   //Contact 1 Attribtues
   String cId = "1";
   String cName = "abc";
   String cPhone = "1234567890";

   //Contact 2 Attribtues
   String cId2 = "2";
   String cName2 = "xyz";
   String cPhone2 = "5555555555";

   //set Contact persistible classes.
   Contact c1 = new Contact();
   c1.setContactID(cId);
   c1.setName(cName);
   c1.setPhone(cPhone);

   Contact c2 = new Contact();
   c2.setContactID(cId2);
   c2.setName(cName2);
   c2.setPhone(cPhone2);

   // Add a list of Contacts
        List contacts = new LinkedList();
        contacts = new ArrayList();
        contacts.add(c1);
   contacts.add(c2);


   //set the Vendor persistible class.
   Vendor vendor = new Vendor();
   vendor.setVendorID(vendorID);
   vendor.setName(vendorName);
   vendor.setContacts(contacts);

   //Instantiate the DAO.
   BaseDAO dao = new BaseDAO();
   dao.configure();
   boolean result = dao.addVendor(vendor);

christian · **Posted:** Tue Oct 07, 2003 10:46 am

Eh, the Contacts should be saved by cascading "all" operations on this association mapping. Your code is good, but I guess you have an "assigned" identifer on the Vendor mapping, not a "foreign"? Otherwise, check the Hibernate log at debug level.

sid · **Posted:** Tue Oct 07, 2003 11:53 am

I already have logging enabled in WLS and get the info messages from HB. How do I enable detailed logging in HB.

Also I am using the foreign id generator for Vendor as I have a one-to-one relationship with Address apart from having a one-to-many relationship with contacts.

I had intentionally left out the address mappings. But it could be the source of the porblem?

Both Vendor and Address get persisted into the DB except for Contacts.

Vendor Mapping:

Code:

<?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="com.poc.Vendor" table="TEST_VENDOR">
       <id name="vendorID" column="VENDORID">
           <generator class="foreign">
            <param name="property">address</param>
           </generator>
        </id>
        <property name="name" column="VENDORNAME"/>
        <one-to-one name="address" class="com.poc.Address"/>
        <bag name="contacts" cascade="all">
           <key column="VENDORID"/>
           <one-to-many class="com.poc.Contact"/>
          </bag>
    </class>
</hibernate-mapping>

Contact Mapping:

Code:

<?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="com.poc.Contact" table="TEST_CONTACT">
        <id name="contactID" column="CONTACTID">
           <generator class="assigned"/>
        </id>
        <property name="name" column="CONTACTNAME"/>
        <property name="phone" column="CONTACTPHONE"/>
    </class>
</hibernate-mapping>

Address Mapping:

Code:

<?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="com.poc.Address" table="TEST_ADDRESS">
        <id name="vendorID" column="VENDORID" unsaved-value="null">
           <generator class="assigned"/>
        </id>
        <property name="city" column="CITY"/>
        <property name="country" column="COUNTRY"/>
        <property name="line1" column="LINE1"/>
        <property name="line2" column="LINE2"/>
        <property name="state" column="STATE"/>
        <property name="zip" column="ZIP"/>
    </class>

</hibernate-mapping>

christian · **Posted:** Tue Oct 07, 2003 11:58 am

Place the example log4j.properties in your application classpath and add log4j.jar. Check the properties.

sid · **Posted:** Tue Oct 07, 2003 12:42 pm

I did as told and got the following log:

Code:

40:23,438  INFO Environment:403 - Hibernate 2.0.3
40:23,458  INFO Environment:437 - loaded properties from resource hibernate.properties: {hibernate.connection.username=ep10, hibernate.connection.password=ep10
40:23,468  INFO Environment:452 - using CGLIB reflection optimizer
40:23,468  INFO Environment:462 - JVM proxy support: true
40:23,478  INFO Configuration:283 - Mapping resource: com/poc/Vendor.hbm.xml
40:23,588  INFO Binder:178 - Mapping class: com.poc.Vendor -> TEST_VENDOR
40:24,229  INFO Configuration:283 - Mapping resource: com/poc/Address.hbm.xml
40:24,269  INFO Binder:178 - Mapping class: com.poc.Address -> TEST_ADDRESS
40:24,279  INFO Configuration:283 - Mapping resource: com/poc/Contact.hbm.xml
40:24,330  INFO Binder:178 - Mapping class: com.poc.Contact -> TEST_CONTACT
40:24,340  INFO Configuration:492 - processing one-to-many association mappings
40:24,340  INFO Binder:1025 - Mapping collection: com.poc.Vendor.contacts -> TEST_CONTACT
40:24,360  INFO Configuration:503 - processing foreign key constraints
40:24,450  INFO SessionFactoryImpl:132 - building session factory
40:24,470  INFO Dialect:83 - Using dialect: net.sf.hibernate.dialect.Oracle9Dialect
40:24,480  INFO DriverManagerConnectionProvider:41 - Hibernate connection pool size: 20
40:24,490  INFO DriverManagerConnectionProvider:70 - using driver: oracle.jdbc.driver.OracleDriver at URL: jdbc:oracle:thin:@localhost:1521:JONE
40:24,490  INFO DriverManagerConnectionProvider:71 - connection properties: {user=ep10, password=ep10}
40:24,500  INFO SessionFactoryImpl:162 - Use outer join fetching: true
40:24,740  INFO SessionFactoryImpl:185 - Use scrollable result sets: true
40:24,740  INFO SessionFactoryImpl:186 - JDBC 2 max batch size: 15
40:25,071  INFO SessionFactoryObjectFactory:82 - no JDNI name configured
40:25,071  INFO SessionFactoryImpl:269 - Query language substitutions: {}

sid · **Posted:** Tue Oct 07, 2003 12:55 pm

Sorry, forgot to turn on the debug level!

Below are the debug level messages:

Code:

50:24,132 DEBUG SessionFactoryImpl:281 - instantiated session factory
50:24,132 DEBUG SessionImpl:413 - opened session
50:24,142 DEBUG SessionImpl:656 - saving [com.poc.Address#004]
50:24,142 DEBUG SessionImpl:656 - saving [com.poc.Vendor#004]
50:24,142 DEBUG Cascades:336 - processing cascades for: com.poc.Vendor
50:24,142 DEBUG Cascades:344 - done processing cascades for: com.poc.Vendor
50:24,142 DEBUG SessionImpl:2520 - Wrapped collection in role: com.poc.Vendor.contacts
50:24,142 DEBUG Cascades:336 - processing cascades for: com.poc.Vendor
50:24,142 DEBUG Cascades:275 - cascading to collection: com.poc.Vendor.contacts
50:24,142 DEBUG Cascades:87 - cascading to saveOrUpdate()
50:24,142 DEBUG Cascades:237 - unsaved-value strategy NULL
50:24,142 DEBUG SessionImpl:1205 - saveOrUpdate() previously saved instance with id: 1
50:24,142 DEBUG SessionImpl:1270 - updating [com.poc.Contact#1]
50:24,142 DEBUG Cascades:87 - cascading to saveOrUpdate()
50:24,152 DEBUG Cascades:237 - unsaved-value strategy NULL
50:24,152 DEBUG SessionImpl:1205 - saveOrUpdate() previously saved instance with id: 2
50:24,152 DEBUG SessionImpl:1270 - updating [com.poc.Contact#2]
50:24,152 DEBUG Cascades:344 - done processing cascades for: com.poc.Vendor
50:24,152 DEBUG SessionImpl:2011 - flushing session
50:24,152 DEBUG Cascades:336 - processing cascades for: com.poc.Vendor
50:24,152 DEBUG Cascades:275 - cascading to collection: com.poc.Vendor.contacts
50:24,152 DEBUG Cascades:87 - cascading to saveOrUpdate()
50:24,162 DEBUG SessionImpl:1183 - saveOrUpdate() persistent instance
50:24,162 DEBUG Cascades:87 - cascading to saveOrUpdate()
50:24,162 DEBUG SessionImpl:1183 - saveOrUpdate() persistent instance
50:24,162 DEBUG Cascades:344 - done processing cascades for: com.poc.Vendor
50:24,162 DEBUG SessionImpl:2113 - Flushing entities and processing referenced collections
50:24,162 DEBUG SessionImpl:2550 - Collection found: [com.poc.Vendor.contacts#004], was: [<unreferenced>]
50:24,172 DEBUG SessionImpl:2209 - Updating entity: [com.poc.Contact#1]
50:24,172 DEBUG SessionImpl:2209 - Updating entity: [com.poc.Contact#2]
50:24,172 DEBUG SessionImpl:2397 - Processing unreferenced collections
50:24,172 DEBUG SessionImpl:2408 - Scheduling collection removes/(re)creates/updates
50:24,172 DEBUG SessionImpl:2023 - Flushed: 2 insertions, 2 updates, 0 deletions to 4 objects
50:24,172 DEBUG SessionImpl:2028 - Flushed: 1 (re)creations, 0 updates, 0 removals to 1 collections
50:24,172 DEBUG SessionImpl:2058 - executing flush
50:24,172 DEBUG EntityPersister:464 - Inserting entity: com.poc.Address#004
50:24,172 DEBUG BatcherImpl:166 - about to open: 0 open PreparedStatements, 0 open ResultSets
50:24,172 DEBUG DriverManagerConnectionProvider:77 - total checked-out connections: 0
50:24,172 DEBUG DriverManagerConnectionProvider:83 - using pooled JDBC connection, pool size: 0
50:24,172 DEBUG SessionFactoryImpl:526 - prepared statement get: insert into TEST_ADDRESS (CITY, COUNTRY, LINE1, LINE2, STATE, ZIP, VENDORID) values
50:24,182 DEBUG SessionFactoryImpl:536 - preparing statement
50:24,182 DEBUG EntityPersister:366 - Dehydrating entity: com.poc.Address#004
50:24,182 DEBUG BatcherImpl:24 - Adding to batch
50:24,182 DEBUG EntityPersister:464 - Inserting entity: com.poc.Vendor#004
50:24,182 DEBUG BatcherImpl:46 - Executing batch size: 1
50:24,182 DEBUG BatcherImpl:173 - done closing: 0 open PreparedStatements, 0 open ResultSets
50:24,182 DEBUG SessionFactoryImpl:554 - closing statement
50:24,192 DEBUG BatcherImpl:166 - about to open: 0 open PreparedStatements, 0 open ResultSets
50:24,192 DEBUG SessionFactoryImpl:526 - prepared statement get: insert into TEST_VENDOR (VENDORNAME, VENDORID) values (?, ?)
50:24,192 DEBUG SessionFactoryImpl:536 - preparing statement
50:24,192 DEBUG EntityPersister:366 - Dehydrating entity: com.poc.Vendor#004
50:24,192 DEBUG BatcherImpl:24 - Adding to batch
50:24,192 DEBUG BatcherImpl:46 - Executing batch size: 1
50:24,202 DEBUG BatcherImpl:173 - done closing: 0 open PreparedStatements, 0 open ResultSets
50:24,202 DEBUG SessionFactoryImpl:554 - closing statement
50:24,202 DEBUG EntityPersister:617 - Updating entity: com.poc.Contact#1
50:24,202 DEBUG BatcherImpl:166 - about to open: 0 open PreparedStatements, 0 open ResultSets
50:24,202 DEBUG SessionFactoryImpl:526 - prepared statement get: update TEST_CONTACT set CONTACTNAME=?, CONTACTPHONE=? where CONTACTID=?
50:24,202 DEBUG SessionFactoryImpl:536 - preparing statement
50:24,202 DEBUG EntityPersister:366 - Dehydrating entity: com.poc.Contact#1
50:24,202 DEBUG BatcherImpl:24 - Adding to batch
50:24,202 DEBUG EntityPersister:617 - Updating entity: com.poc.Contact#2
50:24,202 DEBUG EntityPersister:366 - Dehydrating entity: com.poc.Contact#2
50:24,212 DEBUG BatcherImpl:24 - Adding to batch
50:24,212 DEBUG BatcherImpl:46 - Executing batch size: 2
50:24,212 DEBUG BatcherImpl:173 - done closing: 0 open PreparedStatements, 0 open ResultSets
50:24,212 DEBUG SessionFactoryImpl:554 - closing statement
50:24,212 DEBUG CollectionPersister:617 - Inserting collection: com.poc.Vendor.contacts#004
50:24,222 DEBUG BatcherImpl:166 - about to open: 0 open PreparedStatements, 0 open ResultSets
50:24,222 DEBUG SessionFactoryImpl:526 - prepared statement get: update TEST_CONTACT set VENDORID=? where CONTACTID=?
50:24,222 DEBUG SessionFactoryImpl:536 - preparing statement
50:24,222 DEBUG BatcherImpl:24 - Adding to batch
50:24,222 DEBUG BatcherImpl:24 - Adding to batch
50:24,222 DEBUG CollectionPersister:643 - done inserting collection
50:24,222 DEBUG BatcherImpl:46 - Executing batch size: 2
50:24,232 DEBUG BatcherImpl:173 - done closing: 0 open PreparedStatements, 0 open ResultSets
50:24,232 DEBUG SessionFactoryImpl:554 - closing statement
50:24,232 DEBUG SessionImpl:2428 - post flush
50:24,232 DEBUG SessionImpl:435 - closing session
50:24,232 DEBUG SessionImpl:2930 - disconnecting session
50:24,232 DEBUG DriverManagerConnectionProvider:117 - returning connection to pool, pool size: 1
50:24,232 DEBUG SessionImpl:447 - transaction completion

christian · **Posted:** Tue Oct 07, 2003 1:01 pm

Ah. It tries to update the Contact instead of INSERT. I'm currently not sure what you have to do with assigned identifiers (I assume implementing an Interceptor...) because I'm right now active in a very different area of Hibernate. Steve should be able to answer that immediately.

steve · **Posted:** Tue Oct 07, 2003 2:43 pm

With assigned identifiers you pretty much have two viable approaches:
1) leave the mapping as-is (using the default unsaved-value of "null"), in which case Hibernate will assume all the associations are for update. Then you need to explicitly call session.save() on any new instances.
2) Implement a generator class which "doles out" your assigned identifiers. That way you can ties into the normal Hibernate instance management mechanisms. Whether of not you can do this depends on your app setup.

You could also utilize the Interceptor.isUnsaved() method to tell hibernate whether a particular instance is yet existent in the DB.

My advice... Avoid the "assigned" generation strategy if you can. A custom generator class implementation is a viable alternative to not use the "assigned" id-generation strategy, while still allowing you to manage your ids however you want.