how to retrive entity without duplication even though its child are fetched?

Question

I have object called Property. in this multiple concerns associated.

<class name="Property"
        table="T_PROPERTY">
        <id name="propertyId" type="integer" column="PRTY_ID">
            <generator class="native" />
        </id>

        <property name="propertyName" column="PRTY_NAME" type="string"/>
        <many-to-one name="propertyType" class="com.mmm.ehspreg2.entity.property.PropertyType" column="PRTY_TYP_ID" />
        <property name="active" column="ACTV" type="boolean"/>

                <set name="propertyConcern">
                 <key column="PRTY_ID"/> 
                 <one-to-many class="PropertyConcern"/>
        </set>
    </class>

<class name="PropertyConcern"
        table="T_CONCERN">
        <id name="prtyCrnId" type="integer" column="PRTY_CRN_ID">
            <generator class="native" />
        </id>

        <many-to-one name="concern"
            class="com.mmm.ehspreg2.entity.property.Concern" column="CRN_ID" />
        <many-to-one name="property"
            class="com.mmm.ehspreg2.entity.property.Property" column="PRTY_ID" />

    </class>

So i need List of unique property object,below is my code

Criteria criteria = getPersManager().getCurrentSession()
                .createCriteria(Property.class).createAlias("propertyType",
                        "type").createCriteria("propertyConcern",
                        "propertyConcern", CriteriaSpecification.LEFT_JOIN)
                .createCriteria("propertyConcern.concern",
                        CriteriaSpecification.LEFT_JOIN).setFetchMode("type",
                        FetchMode.JOIN).setFetchMode("propertyConcern",
                        FetchMode.JOIN).setFetchMode("propertyConcern.concern",
                        FetchMode.JOIN).setResultTransformer(
                        CriteriaSpecification.ROOT_ENTITY);

List of property, if i traverse throth property i should get the other objects.I am able to get the other objects, but Property object is getting duplicated.How should i avoid it? Please help me.

Answer 1

Replace setResultTransformer(CriteriaSpecification.ROOT_ENTITY) with setResultTransformer(CriteriaSpecification.DISTINCT_ROOT_ENTITY)

That will do!

EDIT: after reading OP's comment

In this how do i bring propertyConcern==null property on top in the order?

Actually, Orcale does have a concept of NULLS FIRST/LAST (Topic Name : Sorting)

But, I GUESS Criteria API does not have support for this facility (the reason might be that only Oracle (or few RDBMS) support this facility, not sure though).

Ok, whatever the reason why Criterai API does not support this, you can do following trick to make it work.... (assuming that your DB supports Nulls First/Last)

Order o = new Order(${propertyName}, true) {
        @Override
        public String toSqlString(Criteria criteria, org.hibernate.criterion.CriteriaQuery criteriaQuery)
                throws HibernateException {
            return super.toSqlString(criteria, criteriaQuery) + " NULLS FIRST"; /* or LAST*/
        }

    };

where ${propertyName} means the name of property you're gonna sort

then

criteria.addOrder(o);