Question

If I have a mapping like this:

<class name="Users" table="users">
    <id column="id" name="id">
        <generator class="native"/>
    </id>
    ...
    <set name="types" table="types" cascade="all">
        <key column="user_id" />
        <element column="type_name" type="string" />
    </set>
</class>

How should the user object be created? I did this:

User u = new User();
u.getType().add(new Type(type_name));
getHibernateTemplate().save(u);

But there will be the error java.lang.ClassCastException: Type.
The Type class only has an integer user_id and string type_name in it with get/set.

Why doesn’t it work? Where can I find documentation on saving objects with collection of elements? Thanks you so much.

Answer 1

Have a look at http://docs.jboss.org/hibernate/stable/core/reference/en/html/collections.html.

Change the element to:

<element column="type_name" type="Type" />

Then you can add types to the set. Right now you have it defined as String.