Hi All

I'm using hibernate 3.1.2 and annotations 3.1 beta 8.

I'm stuck trying to figure out haw to map a Map of core types e.g.

public Map<String,String> getMyData();

As I understand it, the EJB3 annotations don't support mapping of core types, so I'm not surprised that @OneToMany fails.

According to http://www.hibernate.org/hib_docs/annot ... e/#d0e2065 the hibernate extensions do support collections of core types, using @CollectionOfElements.

I can't make this work for a Map rather than a Set. Is @CollectionOfElements supported for Maps and if so, please could someone provide an example? Right now I'm getting an error ('A Map must declare a @MapKey element') but I can't figure out how to get round it. Adding a @MapKey element is tricky when their is no name to map to!

Thanks

Jonathan.

@MapKey does not make any sense for collection of core types.
support for true maps is not implemented yet (ANN-1)

Ahh, OK thanks. Guess I'll kick back and wait for beta9 then :-)

Jonathan.

I'm currently struggling with this. Would greatly appreciate a pointer to a definitive example re: using annotations to support a Map<String, String>. I've now been through several books, the annotation docs, and this forum. No luck. Thanks.

As I discovered recently, the tests are a good source of examples, often more so than the documentation. The following extract from
test/org/hibernate/test/annotations/collectionelement/Boy.java is close to what you need I think:

@CollectionOfElements
@JoinTable(name = "ScorePerNickName", joinColumns = @JoinColumn(name = "BoyId"))
@Column(name = "score", nullable = false)
public Map<String, Integer> getScorePerNickName() {
return scorePerNickName;
}


Hope this helps

Jonathan.

Actually got this to work last night, but something seems amiss.

I had to do the following...

@MapKey(columns=@Column(name="mapkey"))
public Map <String, String>getProps()
{
return props;
}

...to force the column name output by the hbm2dll schema generation to use the same column name as the hibernate runtime. Otherwise the session operations would fail as the column names did not match.

Is this a bug that should be filed? I just double checked the installed tools. I'm using Tools 3.2.0.beta7, Annotations 3.2.0.CR2, and Hibernate 3.2.0.CR4. But hbm2dll is reporting tools version CR1.

?

you mean a mismatch between the tools and HAN CR2?
This is expected, the versions are not synchronized. This will be fixed with the next version of Tools