Hi,
I have a class C having a map of Product with prduct's id as map's key like the following:

<map name="products" table="C_PRODUCTS" cascade="none">
<key column="C_ID"/>
<index column="PRODUCT_ID" type="string" />
<many-to-many column="PRODUCT_ID" class="Product"/>
</map>

When running program, there is error saying "repeated column declaration". For such mapping, how to do it?

Thanks,
Rice

CAn't do that. You have to merge it at the java level

What is meant by "doint it at Java Level"? It means I have to change my Java model? My current work-around is to change the collection to set, instead of map. Any other way?

Regards,
Rice

Keep map and manually set
map.put(product.getId(), product);
or even better do a addProduct() method doing the job.

If you want a map, you will need an extra index column.

Your replacement with set seems to prove you don't really need an index afterall.

Why is this so ? This seems like a very natural thing to do, that is, use the foreign key as the key to an internal map. I posted a similar question myself.


I disagree. Not being able to do this directly, i.e. having to provide a separate parallel Map leads to redundancy, while using only Set leads to inefficient searches.

Actually we must stay compliant with the Java freedom.
In pure Java code, you can set the index different from the product id. That's why Hibernate mandate the use of an extra index column. I understand you use case, but you should understand the Java way to best understand some Hibernate design decisions.