Error when retrieving child properties in hibernate

Question

Im getting this error, im trying to access a child property using one-to-many relation in hibernate:

org.hibernate.QueryException: illegal attempt to dereference collection [sigtccontr0_.ID_OBJETIVO.children] with element property reference [idIniciativa] [from org.citi.tablero.contraloria.planes.model.db.hibernate.dto.SigTcContraloriaObjetivos p where p.children.idIniciativa = 1]

This is my query:

String sql = "from SigTcContraloriaObjetivos p where p.children.idIniciativa = 1";

Dto ´s:

public class SigTcContraloriaObjetivos {

    private Long idObjetivo;
    private String descripcion;
    private Set<SigTcContraloriaIniciativas> children;

public class SigTcContraloriaIniciativas {

    private Long idIniciativa;
    private String descripcion;
    private Long idObjetivo;

Mappings:

<class dynamic-insert="false" dynamic-update="true" mutable="true"
           name="org.citi.tablero.contraloria.planes.model.db.hibernate.dto.SigTcContraloriaObjetivos"
           optimistic-lock="version" polymorphism="implicit" select-before-update="false"
           table="SIG_TC_CONTRALORIA_OBJETIVOS">
    <id column="ID_OBJETIVO" name="idObjetivo">
        <generator class="sequence">
            <param name="sequence">SEQ_SIG_CONTRALORIA_OBJETIVOS</param>
        </generator>    
    </id>
    <property column="DESCRIPCION" name="descripcion"/>
     <set name="children" inverse="false" cascade="all" lazy="false">
        <key column="ID_OBJETIVO"/>
        <one-to-many class="SigTcContraloriaIniciativas"/>
    </set>          
</class>

<class dynamic-insert="false" dynamic-update="true" mutable="true" name="org.citi.tablero.contraloria.planes.model.db.hibernate.dto.SigTcContraloriaIniciativas"
        optimistic-lock="version" polymorphism="implicit" select-before-update="false" table="SIG_TC_CONTRALORIA_INICIATIVAS">
    <id column="ID_INICIATIVA" name="idIniciativa">
        <generator class="sequence">
            <param name="sequence">SEQ_SIG_CONTRALORIA_INICIATIVA</param>
        </generator>    
    </id>
    <property column="DESCRIPCION" name="descripcion"/>
    <property column="ID_OBJETIVO" name="idObjetivo" /> 

</class>

Any idea how to access to idIniciativa ?

Update: when using the query provided: "select p from SigTcContraloriaObjetivos p join p.children c where c.idIniciativa = 1"

query.list() returns:

Object1:

1. SigTcContraloriaObjetivos 1.1 SigTcContraloriaIniciativas (child)
2. SigTcContraloriaIniciativas

Object2:

1. SigTcContraloriaObjetivos 1.1 SigTcContraloriaIniciativas (child)
2. SigTcContraloriaIniciativas

And i need:

1. Object 1: SigTcContraloriaObjetivos -> SigTcContraloriaIniciativas (Child)
2. Object 2: SigTcContraloriaObjetivos -> SigTcContraloriaIniciativas (Child)

Answer 1

You cannot access a collection that way with Hibernate. Something like the following should work:

select p from SigTcContraloriaObjetivos p join p.children c where c.idIniciativa = 1

See here for more info: http://docs.jboss.org/hibernate/core/3.3/reference/en/html/queryhql.html#queryhql-joins

Note, this is for Hibernate 3.3.