Criteria JPA 2 with 3 tables

Question

I\'m trying to create a criteria to retrieve some objects from 3 tables (Associate, Update and Detail). A Detail has reference to Associate and Update, and an Update has ref

Answer 1

For three tables involved.

CriteriaBuilder builder = theEntityManager.getCriteriaBuilder(); CriteriaQuery query1 = builder.createQuery(BasicMemberInfo.class);

    Root<Table1> table1 = query1.from(Table1.class); 
    Root<Table2> table2 = query1.from(Table2.class);
    Root<Table3> table3 = query1.from(Table3.class);

   List<Predicate> conditions = new ArrayList();
    conditions.add(builder.equal(table3.get("Table1").get("memberId"), table1.get("memberId")));
    conditions.add(builder.equal(table2.get("tableid").get("memberId"), table1.get("memberId")));
    conditions.add(builder.equal(table2.get("indicator"), 'Y'));
    conditions.add(builder.equal(table3.get("StatusCd"), "YES"));

    TypedQuery<BasicCustInfo> typedQuery = theEntityManager.createQuery(
            query1.multiselect(table1.get("memberId"), table2.get("AcctId"))
            .where(conditions.toArray(new Predicate[] {}))
    );

    List<BasicMemberInfo> custList = typedQuery.getResultList();

public class BasicMemberInfo {

String memberId;
String AcctId;

public BasicCustInfo() {
    // TODO Auto-generated constructor stub
}

public BasicMemberInfo( BigDecimal memberId,String AcctId ) {
    this.memberId = memberId;
    this.AcctId = AcctId;
}

public BigDecimal getmemberId() {
    return memberId;
}
public void setmemberId(BigDecimal memberId) {
    memberId = memberId;
}
public String getAcctId() {
    return AcctId;
}
public void setAcctId(String AcctId) {
    AcctId = AcctId;
}

}

Answer 2

Checkout this test with even more than three tables . Also use static meta model instead of using direct attribute names.

    @Test
@Rollback(false)
@Transactional
public void   
fetch() {
    CriteriaBuilder cb = 
entityManager.getCriteriaBuilder();
    CriteriaQuery<Instructor> cq = 
cb.createQuery(Instructor.class);
    Root<Instructor> root = 
cq.from(Instructor.class);
    root.join(Instructor_.idProof);
    root.join(Instructor_.vehicles);
    Join<Instructor, Student> insStuJoin = 
root.join(Instructor_.students);
    insStuJoin.join(Student_.instructors);
    Join<Student, Vehicle> stuVehcileJoin.   
= insStuJoin.join(Student_.vehicles);
    Join<Vehicle, Document> 
vehicleDocumentJoin = 
stuVehcileJoin.join(Vehicle_.documents);

DataPrinters.
listDataPrinter.accept.   
(queryExecutor.fetchListForCriteriaQuery
      (cq.select(root).where
(cb.greaterThan(root.get(Instructor_.id), 2),                        
           cb.in(vehicleDocumentJoin.get
                          (Document_.name)).value("1")
.value("2").value("3")));
}

Answer 3

Each join takes you from the leftish type parameter to the rightish one. So, the details join of my code (second line) starts from fromUpdates, that is a Path<Update>, and creates something which is behind the scenes also a Path<Detail>. From that, you can build other joins. Try this (code not tested):

Root<Update> fromUpdates = query.from(Update.class);
Join<Update, Detail> details = fromUpdates.join("details");
Join<Detail, Associate> associate = details.join("associate");
List<Predicate> conditions = new ArrayList();
conditions.add(builder.equal(associate.get("associateId"), associateId));
conditions.add(builder.isNull(details.get("ack_date")));

TypedQuery<Update> typedQuery = em.createQuery(query
        .select(fromUpdates)
        .where(conditions.toArray(new Predicate[] {}))
        .orderBy(builder.asc(fromUpdates.get("updateId")))
        .distinct(true)
);