Setup: **DataBase Tables** 1. USER table: Columns: USER_ID integer not null primary key,
USER_NAME varchar(256) not null, Rows: (1, 'Ann');
(2, 'Bob'); 2. ROLE table Columns: ROLE_ID integer not null primary key,
ROLE_NAME varchar(256) not null, Rows: (1, 'Manager');
(2, 'Developer'); 3. USER_ROLE table Columns: USER_ID integer not null,
ROLE_ID integer not null, Composite key: (USER_ID, ROLE_ID) Rows: (1,1); **EntityBeans** 4. User.java import jakarta.persistence.CascadeType;
import jakarta.persistence.Column;
import jakarta.persistence.Entity;
import jakarta.persistence.FetchType;
import jakarta.persistence.Id;
import jakarta.persistence.JoinColumn;
import jakarta.persistence.JoinTable;
import jakarta.persistence.ManyToMany;
import jakarta.persistence.Table;
import java.util.Objects;
import java.util.Set;
import org.hibernate.annotations.Fetch;
import org.hibernate.annotations.FetchMode; @Entity
@Table(name = "USER", schema = "TEST")
public class User { private Integer userId = null;
private String userName = null;
private Set<Role> roles = null; @Id
@Column(name = "USER_ID")
public Integer getUserId() { return userId; } public void setUserId(Integer userId) { this.userId = userId; } @Column(name = "USER_NAME")
public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } @ManyToMany(cascade = CascadeType.PERSIST, fetch = FetchType.EAGER)
@JoinTable(
name = "USER_ROLE",
schema = "TEST",
joinColumns = @JoinColumn(name = "USER_ID"),
inverseJoinColumns = @JoinColumn(name = "ROLE_ID"))
@Fetch(FetchMode.SUBSELECT)
public Set<Role> getRoles() { return roles; } public void setRoles(Set<Role> roles) { this.roles = roles; } @Override
public boolean equals(Object o) {
if (this == o) { return true; }
if (o == null || getClass() != o.getClass()) { return false; }
User user = (User) o;
return Objects.equals(userId, user.userId) && Objects.equals(userName,
user.userName) && Objects.equals(roles, user.roles);
}
@Override
public int hashCode() { return Objects.hash(userId, userName, roles); }
}
5. Role.java
import jakarta.persistence.Column;
import jakarta.persistence.Entity;
import jakarta.persistence.Id;
import jakarta.persistence.Table;
import java.util.Objects;
@Entity
@Table(name = "ROLE", schema = "TEST")
public class Role {
private Integer roleId = null;
private String roleName = null;
@Id
@Column(name = "ROLE_ID")
public Integer getRoleId() { return roleId; }
public void setRoleId(Integer roleId) { this.roleId = roleId; }
@Column(name = "ROLE_NAME")
public String getRoleName() { return roleName; }
public void setRoleName(String roleName) { this.roleName = roleName; }
@Override
public boolean equals(Object o) {
if (this == o) { return true; } if (o == null || getClass() != o.getClass()) { return false; } Role role = (Role) o;
return Objects.equals(roleId, role.roleId) && Objects.equals(roleName,
role.roleName);
} @Override
public int hashCode() { return Objects.hash(roleId, roleName); } } **Query and Error** 6. This query works: String query1 = "FROM User WHERE userId = 1"; // Obtain Hibernate session
Session session = getSession();
List<User> userList = session.createQuery(query1, User.class).list(); 7. This query threw java.lang.NullPointerException: String query2 = "FROM User WHERE userId = 2";
// Obtain Hibernate session
Session session = getSession();
List<User> userList = session.createQuery(query2, User.class).list(); The full stack traces – Original Exception:
java.lang.NullPointerException: Cannot invoke "org.hibernate.engine.spi.EntityEntry.getEntityKey()" because "ownerEntry" is null
at org.hibernate.loader.ast.internal.CollectionLoaderSubSelectFetch.load(CollectionLoaderSubSelectFetch.java:91)
at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:815)
at org.hibernate.event.internal.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:75)
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:107)
at org.hibernate.internal.SessionImpl.initializeCollection(SessionImpl.java:1706)
at org.hibernate.collection.spi.AbstractPersistentCollection.lambda$initialize$3(AbstractPersistentCollection.java:609)
at org.hibernate.collection.spi.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:265)
at org.hibernate.collection.spi.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:607)
at org.hibernate.collection.spi.AbstractPersistentCollection.forceInitialization(AbstractPersistentCollection.java:805)
at org.hibernate.engine.internal.StatefulPersistenceContext.initializeNonLazyCollections(StatefulPersistenceContext.java:991)
at org.hibernate.engine.internal.StatefulPersistenceContext.initializeNonLazyCollections(StatefulPersistenceContext.java:977)
at org.hibernate.sql.results.spi.ListResultsConsumer.consume(ListResultsConsumer.java:170)
at org.hibernate.sql.results.spi.ListResultsConsumer.consume(ListResultsConsumer.java:32)
at org.hibernate.sql.exec.internal.JdbcSelectExecutorStandardImpl.doExecuteQuery(JdbcSelectExecutorStandardImpl.java:437)
at org.hibernate.sql.exec.internal.JdbcSelectExecutorStandardImpl.executeQuery(JdbcSelectExecutorStandardImpl.java:166)
at org.hibernate.sql.exec.internal.JdbcSelectExecutorStandardImpl.list(JdbcSelectExecutorStandardImpl.java:91)
at org.hibernate.sql.exec.spi.JdbcSelectExecutor.list(JdbcSelectExecutor.java:31)
at org.hibernate.loader.ast.internal.SingleIdLoadPlan.load(SingleIdLoadPlan.java:140)
at org.hibernate.loader.ast.internal.SingleIdLoadPlan.load(SingleIdLoadPlan.java:110)
at org.hibernate.loader.ast.internal.SingleIdEntityLoaderStandardImpl.load(SingleIdEntityLoaderStandardImpl.java:72)
at org.hibernate.persister.entity.AbstractEntityPersister.doLoad(AbstractEntityPersister.java:4313)
at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:4303)
at org.hibernate.event.internal.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:598)
at org.hibernate.event.internal.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:571)
at org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:223)
at org.hibernate.event.internal.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:362)
at org.hibernate.event.internal.DefaultLoadEventListener.doOnLoad(DefaultLoadEventListener.java:112)
at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:74)
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:118)
at org.hibernate.internal.SessionImpl.fireLoadNoChecks(SessionImpl.java:1237)
at org.hibernate.internal.SessionImpl.internalLoad(SessionImpl.java:1090)
at org.hibernate.sql.results.graph.entity.internal.EntitySelectFetchInitializer.initializeInstance(EntitySelectFetchInitializer.java:197)
at org.hibernate.sql.results.internal.StandardRowReader.coordinateInitializers(StandardRowReader.java:153)
at org.hibernate.sql.results.internal.StandardRowReader.readRow(StandardRowReader.java:98)
at org.hibernate.sql.results.spi.ListResultsConsumer.consume(ListResultsConsumer.java:143)
at org.hibernate.sql.results.spi.ListResultsConsumer.consume(ListResultsConsumer.java:32)
at org.hibernate.sql.exec.internal.JdbcSelectExecutorStandardImpl.doExecuteQuery(JdbcSelectExecutorStandardImpl.java:437)
at org.hibernate.sql.exec.internal.JdbcSelectExecutorStandardImpl.executeQuery(JdbcSelectExecutorStandardImpl.java:166)
at org.hibernate.sql.exec.internal.JdbcSelectExecutorStandardImpl.list(JdbcSelectExecutorStandardImpl.java:91)
at org.hibernate.sql.exec.spi.JdbcSelectExecutor.list(JdbcSelectExecutor.java:31)
at org.hibernate.query.sqm.internal.ConcreteSqmSelectQueryPlan.lambda$new$0(ConcreteSqmSelectQueryPlan.java:102)
at org.hibernate.query.sqm.internal.ConcreteSqmSelectQueryPlan.withCacheableSqmInterpretation(ConcreteSqmSelectQueryPlan.java:305)
at org.hibernate.query.sqm.internal.ConcreteSqmSelectQueryPlan.performList(ConcreteSqmSelectQueryPlan.java:246)
at org.hibernate.query.sqm.internal.QuerySqmImpl.doList(QuerySqmImpl.java:537)
at org.hibernate.query.spi.AbstractSelectionQuery.list(AbstractSelectionQuery.java:363)
at org.hibernate.query.sqm.internal.QuerySqmImpl.list(QuerySqmImpl.java:987) |
