Hi,

I was read the tutorial about parent/child map and in

http://www.hibernate.org/hib_docs/v3/reference/en/html/example-parentchild.html

he use a Set but my system I Need a List(ArrayList) but when change:
<set name="children">
<key column="parent_id"/>
<one-to-many class="Child"/>
</set>

to:

<list name="children">
<key column="parent_id"/>
<one-to-many class="Child"/>
</list>

hibernate doesn't work. hibernate says that List need add more xml elements !

how I Map this association with List instead of Set ?

thanks !

Alex

If you are using the list, then you need to define the list-index.
Because in list we have the indexing property.

So now you can try with this.

<list name="children">
<list-index column="children_index"/>
<key column="parent_id"/>
<one-to-many class="Child"/>
</list>

Enjoy !!

rahul dongre is right. You need to add the list-index column to the xml file which define the primary key column in your table. Also, if your table has more than one key you can use composite key.

ok,thanks... but What it do ?

because I add

<list-index column="something" />

and I not have any column called something ! and works, I can put anything column ? and work.

the documentation says:

column_name (required): The name of the column holding the collection index values.

why I need it ?

thanks

list-index column just like the primary key column in your table.
For example, if you have two tables like the following
Parent(
ParentId int Primary key,
FName,
LName
)

Child(
ChildId int Primary key,
ParentId int,
FName,
LName
)

Then Child Id is the List-index which make each element in your list is unique.

[quote]the documentation says:

column_name (required): The name of the column holding the collection index values.

why I need it ?[/quote]

Hi,

Indexing is required by java, not defined by hibernate.

When we look back to core java collection API, we need the index for the list. Based on the index on the list we can perform various operations.

I hope you got the point.

If you need any help do let me know.

Thanks
Rahul