Hibernate One To Many Mapping 2 Levels

Question

I have 3 Tables - Lease Account, Lease, Transaction. Each Lease Account has N Leases, each Lease has N Transactions. I am allowed to do only 1 query to the database - Select * from Lease Account, to fetch all this data into Java as N Lease Account objects - each Lease Account object containing a of Lease objects - each Lease containing a of Transaction objects.

Can somebody please guide me on how to write the one to many mapping (hbm.xml) for this scenario in Hibernate(3.2) ?

Thanks.

http://viralpatel.net/blogs/hibernate-one-to-many-xml-mapping-tutorial/ — pratim_b, May 19 '14 at 05:29

score 0 · Answer 1 · edited May 23 '17 at 10:25

In your lease account hbm xml

<class name="LeaseAccounts" table="lease">

    <id name="leaseAccountsId" type="java.lang.Long" column="id" >
        <generator class="native" />
    </id>

<set name="lease" table="lease_accounts"
                    inverse="true" lazy="true" fetch="select">
                <key>
                    <column name="id" not-null="true" />
                </key>
                <one-to-many class="Lease.class" />
            </set>


</class>

Similarly you can write for your lease table.
NB: Select * will load all data or not depends upon your lazy initialization. If lazy loading is set to true , then your need to do Hibernate.initialize(your collection)

(The lazy attribute tells hibernate when to get the children. The fetch attribute tells hibernate how to get the children.)

Hibernate One To Many Mapping 2 Levels

1 Answers1