Mapping a Map Collection

[jsb]

Can someone explain how mapping a Map collection of entities within an entity works and how it should be done? Or perhaps point me to documentation on the subject? So far, I've found only this:
http://www.hibernate.org/hib_docs/annotations/reference/en/html/entity.html#entity-mapping-association-collections
...which looks promising, but I'm not sure how to set up my entities or if it is intended to work how I am thinking it will.

Background on what I'm trying to do: I have entities that have n properties that I am storing as key/value pairs. Currently an entity has a collection of properties stored in a Set. Something like this...

@Entity
public class ItemA {
 private long id;
 private Set<Property> properties;

 @Id(generate = GeneratorType.AUTO)
 public long getId() {
 return id;
 }
 public void setId(long id) {
 this.id = id;
 }
@OneToMany(cascade=CascadeType.ALL, fetch=FetchType.EAGER)
 @JoinTable(
 table = @Table(name = "ItemA_Properties"),
 joinColumns = @JoinColumn(name = "Property_id", referencedColumnName = "id"),
 inverseJoinColumns = @JoinColumn(name = "ItemA_id", referencedColumnName = "id")
 )
 public Set<Property> getProperties() {
 return properties;
 }
 public void setProperties(Set<Property> properties) {
 this.properties = properties;
 }
}

@Entity
public class Property {
 private long id;
 private String propKey;
 private String propValue;

 @Id(generate = GeneratorType.AUTO)
 public long getId() {
 return id;
 }
 public void setId(long id) {
 this.id = id;
 }
 public String getPropKey() {
 return propKey;
 }
 public void setPropKey(String propKey) {
 this.propKey = propKey;
 }
 public String getPropValue() {
 return propValue;
 }
 public void setPropValue(String propValue) {
 this.propValue = propValue;
 }
}

This works simply enough, but what would make more sense is if the "properties" collection was a Map. Simply changing the "properties" collection to a "Map<String, Properties>" and setting a "@MapKey(name="propKey")" annotation doesn't seem to be the answer. I get the feeling I'm missing something obvious.

Thanks for any help on mapping Maps that can be offered,
Jonn

[epbernard]

this should work, what's wrong?

[jsb]

Sorry for the delay in response...

If my entities look something like this:

@Entity
public class ItemA {
 private long id;
 private Map<String, Property> properties;

 @Id(generate = GeneratorType.AUTO)
 public long getId() {
 return id;
 }
 public void setId(long id) {
 this.id = id;
 }
@OneToMany(cascade=CascadeType.ALL, fetch=FetchType.EAGER)
 @JoinTable(
 table = @Table(name = "ItemA_Properties"),
 joinColumns = @JoinColumn(name = "ItemA_id", referencedColumnName = "id"),
 inverseJoinColumns = @JoinColumn(name = "Property_id", referencedColumnName = "id")
 )
 public Map<String, Property> getProperties() {
 return properties;
 }
 public void setProperties(Map<String, Property> properties) {
 this.properties = properties;
 }
}

@Entity
public class Property {
 private long id;
 private String propKey;
 private String propValue;

 @Id(generate = GeneratorType.AUTO)
 public long getId() {
 return id;
 }
 public void setId(long id) {
 this.id = id;
 }
 public String getPropKey() {
 return propKey;
 }
 public void setPropKey(String propKey) {
 this.propKey = propKey;
 }
 public String getPropValue() {
 return propValue;
 }
 public void setPropValue(String propValue) {
 this.propValue = propValue;
 }
}

...I seem to be able to save ItemA objects with Maps of properties. But when I try to retreive the ItemA objects, I get these errors:

2006-01-10 00:28:32,703 DEBUG [com.example.test.ejb.ItemManagerBean] getItems: called
2006-01-10 00:28:32,718 WARN [org.hibernate.util.JDBCExceptionReporter] SQL Error: 0, SQLState: 42703
2006-01-10 00:28:32,718 ERROR [org.hibernate.util.JDBCExceptionReporter] ERROR: column properties0_.propkey does not exist

...followed by an exception stack that includes this:

Caused by: javax.ejb.EJBTransactionRolledbackException: null; CausedByException is:
 could not initialize a collection: [com.example.test.par.ItemA.properties#1]
 at org.jboss.ejb3.tx.Ejb3TxPolicy.handleInCallerTx(Ejb3TxPolicy.java:65)
 at org.jboss.aspects.tx.TxPolicy.invokeInCallerTx(TxPolicy.java:117)
 at org.jboss.aspects.tx.TxInterceptor$Required.invoke(TxInterceptor.java:138)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:98)
 at org.jboss.aspects.tx.TxPropagationInterceptor.invoke(TxPropagationInterceptor.java:61)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:98)
 at org.jboss.ejb3.stateless.StatelessInstanceInterceptor.invoke(StatelessInstanceInterceptor.java:39)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:98)
 at org.jboss.aspects.security.AuthenticationInterceptor.invoke(AuthenticationInterceptor.java:63)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:98)
 at org.jboss.ejb3.ENCPropagationInterceptor.invoke(ENCPropagationInterceptor.java:32)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:98)
 at org.jboss.ejb3.asynchronous.AsynchronousInterceptor.invoke(AsynchronousInterceptor.java:91)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:98)
 at org.jboss.ejb3.stateless.StatelessContainer.dynamicInvoke(StatelessContainer.java:204)
 at org.jboss.aop.Dispatcher.invoke(Dispatcher.java:107)
 at org.jboss.ejb3.remoting.IsLocalInterceptor.invoke(IsLocalInterceptor.java:37)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:98)
 at org.jboss.ejb3.stateless.StatelessRemoteProxy.invoke(StatelessRemoteProxy.java:88)
 at $Proxy105.getItems(Unknown Source)
 at com.example.test.ejb.TestServiceBean.testItemManager(TestServiceBean.java:69)
 at com.example.test.ejb.TestServiceBean.testItem(TestServiceBean.java:101)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:585)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:109)
 at org.jboss.ejb3.AllowedOperationsInterceptor.invoke(AllowedOperationsInterceptor.java:32)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:98)
 at org.jboss.aspects.tx.TxPolicy.invokeInOurTx(TxPolicy.java:66)
 at org.jboss.aspects.tx.TxInterceptor$Required.invoke(TxInterceptor.java:134)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:98)
 at org.jboss.aspects.tx.TxPropagationInterceptor.invoke(TxPropagationInterceptor.java:61)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:98)
 at org.jboss.aspects.security.AuthenticationInterceptor.invoke(AuthenticationInterceptor.java:63)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:98)
 at org.jboss.ejb3.ENCPropagationInterceptor.invoke(ENCPropagationInterceptor.java:32)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:98)
 at org.jboss.ejb3.asynchronous.AsynchronousInterceptor.invoke(AsynchronousInterceptor.java:91)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:98)
 at org.jboss.ejb3.service.ServiceContainer.localInvoke(ServiceContainer.java:151)
 at org.jboss.ejb3.service.ServiceLocalProxy.invoke(ServiceLocalProxy.java:57)
 at $Proxy112.testItem(Unknown Source)
 at com.example.test.web.ItemBean.getItemTest(ItemBean.java:32)
 ... 58 more

Notice anything I could be doing wrong?

[jsb]

Oops! I forgot to include the @MapKey(name="propKey") in my ItemA example entity. I do have this in place in the code I am testing.

[jsb]

This looks like the same issue:
http://opensource2.atlassian.com/projects/hibernate/browse/ANN-120

I was able to get it to work by switching to the @JoinColumn relational strategy, but in my actual project I am using the Property entities with multiple owning entities so join table per owning entity makes more sense.