CODEWITHSUNDEEP
hibernatemany-to-manyassociationshbm
Marvo
Marvo

Reputation: 18133

Hibernate: many-to-many association is empty

My app has leagues, and each league can have any number of competitions. I use .hbm.xml files to set up an association between leagues and competitions. I've configured it as follows:

<set name="competitions" table="leagueCompetitions" lazy="false">
    <meta attribute="property-type"><![CDATA[Set< Competition >]]></meta>
    <meta attribute="default-value"><![CDATA[new HashSet< Competition >()]]></meta>
    <key column="leagueId"/>
    <many-to-many column="competitionId"
            unique="true"
            lazy="false"
            class="com.example.model.Competition"/>
</set>

I have a DAO method that retrieves a list of leagues that essentially comes down to 

Query query = session.createQuery( "from League" );
return query.list();

I wrote some code to count the competitions, and it was as simple as

if ( league.getCompetitions().size() > 0 ) { ... blahditty blah ... }

But it failed because getCompetitions() always is an empty set.

Question: When I use LeagueDAO.list() to get a list of leagues, should not each league have all of its competitions loaded as well?

Upvotes: 0

Views: 886

Answers (2)

Marvo
Marvo

Reputation: 18133

Turns out that my hbm.xml configuration was invalid. I had a many-to-many configuration on one table, and a many-to-one on the opposite side of the association. The result was just a mess.

Upvotes: 1

mprabhat
mprabhat

Reputation: 20323

Add cascade="all"

<set name="competitions" table="leagueCompetitions" lazy="false" cascade="all">
<meta attribute="property-type"><![CDATA[Set< Competition >]]></meta>
<meta attribute="default-value"><![CDATA[new HashSet< Competition >()]]></meta>
<key column="leagueId"/>
<many-to-many column="competitionId"
        unique="true"
        lazy="false"
        class="com.example.model.Competition"/>

Upvotes: 2

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