Mapping an object in Hibernate that has 2 lists causing problems

Question

I'm trying to save an object that has 2 similar lists using a hbm.xml file. Below is my model object and HBM:

public class MyClass {

...

    private List<MyType> list;

    private List<MyType> otherList;

...

}

My HMB for this section is as follows:

    <list name="list" cascade="all-delete-orphan"
        lazy="false">
        <key column="USER_ID" />
        <list-index column="index" />
        <one-to-many class="path.to.MyType" />
    </list>

    <list name="otherList" cascade="all-delete-orphan"
        lazy="false">
        <key column="USER_ID" />
        <list-index column="index" />
        <one-to-many class="path.to.MyType" />
    </list>

However, when this object gets populated from the database, whatever I expect to be in 'list' is also showing up in 'otherList'. I imagine I'm missing a simple configuration change to allow hibernate to store these 2 lists properly, but I can't figure it out.

Any help?

Hey there, see my comment on the answer below for more clarification. — thedude19
– thedude19, Commented May 10, 2011 at 15:54

matt b · Accepted Answer · 2011-05-10 15:51:35Z

2

The <list>s contain the same content because you are telling Hibernate to map the same class (path.to.MyType) using the same <key column="USER_ID"> in both instances. Are you sure you haven't made an error in the Hibernate mapping?

Conceptually, what Hibernate will do to materialize these collections is issue a query like

SELECT m.* from MyType m where m.USER_ID = this.USER_ID

If you tell Hibernate to use the same query to map both list and otherList, how can it return different results for the same query?

answered May 10, 2011 at 15:51

matt b

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3 Comments

thedude19 Over a year ago

I see exactly what you mean, but I'm unsure as to the correct way to do it. Basically, I'm looking to store 2 separate lists of MyType for each user, hence the USER_ID being the key. This obviously works fine if there is 1 list, but I'm not sure what changes I need to make to allow 2 lists to be stored of the same type.

matt b Over a year ago

Well, it might be helpful to ignore Hibernate and think of how you would model this, both in the table structure and with SQL queries - what column would serve as the link to the MyType table for list1 and what column would serve as the link for list2? You may also want to read over the chapter in the Hibernate reference manual on associations, which includes lots of examples of different ways to model different types of associations between classes.

thedude19 Over a year ago

MyType has a boolean column that identifies which list the row should be in (along with USER_ID). Basically what I'm looking for is the select statements to be able to say 'SELECT m.* from MyType m where m.USER_ID = this.USER_ID and m.MY_BOOLEAN = true/false' That should do the trick I would think, but again unsure how this is done in hibernate mappings.

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