Develop Reference

How to create complex join between three tables using Hibernate?

I have three tables (I'll list only important fields):
Format
id
template_id
parameterisation_id
Param
name
value
parameterisation_id
ParamDict
name
template_id
I need to map params into formats into one-to-many association, but they do not have direct connection and needed to be joined through ParamDict table.
I currently did it with #JoinTable like so:
#Entity
#Table(schema = "123", name = "format")
public class Format implements Serializable {
#Id
private Long id;
private String template_id;
private String parameterisation_id;
#OneToMany(fetch = FetchType.EAGER)
#JoinTable(name = "paramDict", schema = "123",
joinColumns = {#JoinColumn(name = "template_id", referencedColumnName =
"template_id",insertable = false,updatable = false)},
inverseJoinColumns = {#JoinColumn(name = "param_name", referencedColumnName =
"param_name",insertable = false,updatable = false)})
private Set<Param> params = new HashSet<>()
}
And in sql it looks like this
Select * from
Format f
left join ParamDict pd on f.template_id = pd.template_id
left join Param p on p.name = pd.name;
But now i need to add another condition in Param join:
Select * from
Format f
left join ParamDict pd on f.template_id = pd.template_id
left join Param p on (p.name = pd.name and p.parameterisation_id = f.parameterisation_id);
I tried to add where clause into #Query annotation in my Repository:
public interface FormatRepository extends Repository<Format, String> {
#Query("select n from format f "
+ "left join fetch f.params p "
+ "where f.parameterisation_id in (?1) "
+ "and f.parameterisation_id = p.parameterisation_id"
)
Set<Format> findBypParameterisationIdIn(List<String> ids);
}
And it created right sql query, but Hibernate does not count that condition (f.parameterisation_id = p.parameterisation_id) when mapping query results into class objects, and i get wrong results in Param set (there are items in the params set, that does not have the same parameterisation_id as Format).
How can i do it via Hibernate mapping?

Named query for entity that does not associate with a specific table

I'm using Quarkus and Hibernate / Panache.
For this example, I have 3 tables (table_a, table_b, table_c) that I am joining together using a native query. In the project I'm working on, it's around 5 JOIN tables to retrieve the information I'm looking for.
table_b is purely a mapping / join table for table_a and table_c:
SELECT
a.id,
a.name,
c.login_date
FROM
table_a a
JOIN table_b b ON b.a_id = a.id
JOIN table_c c ON b.c_id = c.id
WHERE
c.login_date > '01-MAY-21'
I'm porting the above to HQL. I've mapped all my #Entity classes with their respective #Table, along with their #Column names. We're good in that department.
SELECT
a.id,
a.name,
c.loginDate
FROM
TableA a
JOIN TableA b ON b.aId = a.id
JOIN TableB c ON b.cId = c.id
WHERE
c.loginDate > '01-MAY-21'
I'm only looking for name and login_date. There is a bunch of other information stored in table_a and table_c that I don't want for this specific query. So I created an entity for this call:
#Entity
#IdClass(LoginDetailsPk.class)
#NamedQuery(
name = "LoginDetails.findFromDate",
query = "FROM TableA a " +
"JOIN TableA b ON b.aId = a.id " +
"JOIN TableB c ON b.cId = c.id " +
"WHERE c.loginDate > '01-MAY-21'"
)
public class LoginDetails extends PanacheEntityBase {
#Id
private int id;
#Id
private String name;
#Id
private String loginDate;
public static List<LoginDetails> findFromDate(String fromDate) {
// Eventually pass fromDate into find()
return find("#LoginDetails.findFromDate").list();
}
}
I'm having a hard time trying to understand why the return even works. When I invoke LoginDetails.findFromDate(...) and store it in a List<LoginDetails>, it works fine. However, when I try to access the list, I get a ClassCastException error.
List<LoginDetails> details = LoginDetails.findFromDate(null);
for(LoginDetails detail : details) { // <------ Throws a class cast exception
//...
}
After debugging, I'm noticing that generic type stored in my List isn't even my LoginDetails class; rather, it's an array of objects (List<Object[]>) with all my #Entities and the irrelevant information I'm not looking for.
I'm lost. Would it make more sense to move back to a native query?

Your HQL is creating a Object[] for every row in the result, because you are not specifying any SELECT, and by default all the objects in the FROM clause are included in that Object array. If you want to return a LoginDetails object you need to create a constructor with all the attributes:
public LoginDetails(int id, String name, String loginDate) {
this.id = id;
this.name = name;
this.loginDate = loginDate;
}
And then change the query to:
query = "SELECT new LoginDetails(a.id, a.name, c.loginDate) "
"FROM TableA a " +
"JOIN TableA b ON b.aId = a.id " +
"JOIN TableB c ON b.cId = c.id " +
"WHERE c.loginDate > '01-MAY-21'"
See https://docs.jboss.org/hibernate/core/3.5/reference/en/html/queryhql.html#queryhql-select

Spring Data JPA Distinct Returning Duplicate Values

In my Spring boot application I have a query which should return a distinct List of Focus' (works perfectly in MySQL)
#Query(value = "SELECT DISTINCT * FROM Focus F " +
"JOIN FrameworkFoci FF on FF.focusID = F.focusID " +
"JOIN FocusGroups FG on FF.frameworkID = FG.frameworkID " +
"JOIN GroupMembers GM on FG.groupID = GM.groupID " +
"JOIN Users U on GM.userID = U.userID " +
"WHERE U.userID = :userID", nativeQuery = true)
List<Focus> findByUserID(#Param("userID") Long userID);
However this does not return distinct values, duplicates are contained in the resulting list. Another issue is that I can't return a whole entity using #Query annotation - changing my query to SELECT DISTINCT(F) FROM Focus F gives the error java.sql.SQLSyntaxErrorException: Unknown column 'F' in 'field list'.
Furthermore, I tried changing adjusting the query to the following
#Query(value = "SELECT DISTINCT * FROM FrameworkFoci FF " +
"JOIN FocusGroups FG on FF.frameworkID = FG.frameworkID " +
"JOIN GroupMembers GM on FG.groupID = GM.groupID " +
"JOIN Users U on GM.userID = U.userID " +
"WHERE U.userID = :userID", nativeQuery = true)
however this produced the error java.sql.SQLException: Column 'focusCategory' not found.
Why is the query not returning distinct values? And why can't I return a whole entity nor use the second query?
Focus Entity:
#Entity
public class Focus {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private Long focusID;
#Column(name = "focusCategory")
private String focusCategory;
private String focusName;
private String focusExplanation;
#OneToMany(mappedBy = "focus")
private Set<Rating> ratings;
#ManyToMany
#JoinTable(name = "FrameworkFoci",
joinColumns = #JoinColumn(
name = "focusID"),
inverseJoinColumns = #JoinColumn(
name = "frameworkID"))
private Set<Framework> frameworks;
//image
protected Focus(){}
public Focus(String focusName, String focusCategory, String focusExplanation) {
this.focusCategory = focusCategory;
this.focusName = focusName;
this.focusExplanation = focusExplanation;
}
public Focus(String focusCategory, String focusName, String focusExplanation, Set<Rating> ratings){
this.focusCategory = focusCategory;
this.focusName = focusName;
this.focusExplanation = focusExplanation;
this.ratings = ratings;
}
public Long getFocusId() {
return focusID;
}
public void setFocusId(Long focusID) {
this.focusID = focusID;
}
public String getFocusCategory() {
return focusCategory;
}
public void setFocusCategory(String focusCategory) {
this.focusCategory = focusCategory;
}
EDIT:
I've switched from SQL to JPQL with the following query:
#Query(value = "SELECT DISTINCT focus FROM Focus focus " +
"WHERE focus.frameworks.groups.groupMembers.user.userID =:userID ")
I now get an error org.hibernate.QueryException: illegal attempt to dereference collection [focus0_.focusID.frameworks] with element property reference [groups]
Framework entity:
#Entity
#JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class,
property = "frameworkID")
public class Framework {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private Long frameworkID;
private String frameworkName;
#ManyToMany
#JoinTable(name = "FrameworkFoci",
joinColumns = #JoinColumn(
name = "frameworkID"),
inverseJoinColumns = #JoinColumn(
name = "focusID"))
private Set<Focus> frameworkFoci = new HashSet<>();
#OneToMany(mappedBy = "framework", fetch = FetchType.EAGER, cascade = CascadeType.REMOVE)
private Set<Group> groups;
public Framework(){}

The following query solves the issue
#Query(value = "SELECT DISTINCT focus FROM Focus focus " +
"JOIN focus.frameworks frameworks " +
"JOIN frameworks.groups groups " +
"JOIN groups.groupMembers groupMembers "+
"WHERE groupMembers.userID =:userID ")
List<Focus> findByUserID(#Param("userID") Long userID);
Frameworks and GroupMembers are collections and hence needed to be joined, otherwise illegal attempt to dereference collection [focus0_.focusID.frameworks] with element property reference [groups] was produced

you should write your query like this:
'
SELECT DISTINCT f FROM Focus F '

The problem stems from you using SQL by specifying nativeQuery = true. SQL doesn't know about entities, just tables.
Since you presumably have many FrameworkFoci rows (and rows in all the other tables) for each Focus row, each Focus row gets repeated for each matching row in FrameworkFoci. This kind of duplicates the Focus row but the resulting rows are still distinct, because they differ in the columns from the other tables.
And then each row gets turned into a Focus entity, probably with a single element in the framework set.
So therefore query doesn't so much return duplicate results as results split into multiple entities.
Fortunately the solution should be fairly simple: Use JPQL which should be perfectly possible, since you're using only simple joins.
The following should give you a start:
#Query(value = "SELECT DISTINCT * FROM Focus F " +
"WHERE F.framework.groupMembers.user.id=:userID")
List<Focus> findByUserID(#Param("userID") Long userID);

JPA: How to avoid generating multiple "select from" queries

This is not classical N+1 problem. My issue is conserning using projections and DTO objects in Jpa.
I have next method with JPA Query:
public List<MeterDTO> getAllBrokenMeterByHouseServ(House house, Serv serv, Date dt) {
Query query =em.createQuery("select new MeterDTO(m, g.kart.lsk, nvl(e.tp,0)) from Meter m "
+ "join m.exs e with m.id=e.meter.id "
+ "join m.meterLog g with m.meterLog.id=g.id "
+ "join g.kart k with g.kart.id=k.id and :dt between k.dt1 and k.dt2 "
+ "join g.serv s with g.serv.id=s.id "
+ "join k.kw kw with k.kw.id=kw.id "
+ "join kw.house h with kw.house.id=h.id "
+ "where s.id = :servId "
+ "and kw.house.id = :houseId "
+ "and :dt between e.dt1 and e.dt2 and nvl(e.tp,0) in (2,3,4) "
+ "");
query.setParameter("servId", serv.getId());
query.setParameter("houseId", house.getId());
query.setParameter("dt", dt);
return query.getResultList();
}
I fetch records from the query above into
data transfer object:
meterDao.getAllBrokenMeterByHouseServ(house, serv, dt2).stream().forEach(t-> {
log.info("meter.id={}, lsk={}, tp={} ", t.getMeter().getId(), t.getLsk(), t.getTp());
});
MeterDTO:
#Getter #Setter
public class MeterDTO {
private Meter meter;
private Integer lsk;
private Double tp;
public MeterDTO(Meter meter, Integer lsk, Double tp) {
super();
this.meter = meter;
this.lsk = lsk;
this.tp = tp;
}
}
Why does hibernate produce one main query:
select
meter0_.ID as col_0_0_,
kart3_.lsk as col_1_0_,
nvl(exs1_.TP,
0) as col_2_0_
from
MT.METER meter0_
inner join
MT.METER_EXS exs1_
on meter0_.ID=exs1_.FK_METER
and (
meter0_.ID=exs1_.FK_METER
)
inner join
MT.METER_LOG meterlog2_
on meter0_.FK_METER_LOG=meterlog2_.ID
and (
meter0_.FK_METER_LOG=meterlog2_.ID
)
inner join
AR.KART kart3_
on meterlog2_.FK_KLSK_OBJ=kart3_.FK_KLSK_OBJ
and (
kart3_.lsk=kart3_.lsk
and (
? between kart3_.DT1 and kart3_.DT2
)
)
inner join
AR.KW kw6_
on kart3_.FK_KW=kw6_.ID
and (
kart3_.FK_KW=kw6_.ID
)
inner join
AR.HOUSE house7_
on kw6_.FK_HOUSE=house7_.ID
and (
kw6_.FK_HOUSE=house7_.ID
)
inner join
TR.SERV serv5_
on meterlog2_.FK_SERV=serv5_.ID
and (
meterlog2_.FK_SERV=serv5_.ID
)
where
serv5_.ID=?
and kw6_.FK_HOUSE=?
and (
? between exs1_.DT1 and exs1_.DT2
)
and (
nvl(exs1_.TP, 0) in (
2 , 3 , 4
)
)
and multiple queries with different bind argument "?" to load every entity:
select
meter0_.ID as ID1_44_0_,
meter0_.FK_K_LSK as FK_K_LSK2_44_0_,
meter0_.FK_METER_LOG as FK_METER_LOG4_44_0_,
meter0_.TRANS_RATIO as TRANS_RATIO3_44_0_
from
MT.METER meter0_
where
meter0_.ID=?
How to avoid this issue? I want to load all entities Meter in one main query.
Is it possible?
I use:
<spring-framework.version>5.0.5.RELEASE</spring-framework.version>
<hibernate.version>5.1.0.Final</hibernate.version>
Any help would be greatly appreciated.
upd1
I simplified my JPA query code to this:
public List<MeterDTO> getAllBrokenMeterByHouseServ(House house, Serv serv, Date dt) {
Query query =em.createQuery("select new com.ric.bill.dto.MeterDTO(m) from Meter m ");
}
But it still produces mutiple queries:
select
meter0_.ID as ID1_44_0_,
meter0_.FK_K_LSK as FK_K_LSK2_44_0_,
meter0_.FK_METER_LOG as FK_METER_LOG4_44_0_,
meter0_.TRANS_RATIO as TRANS_RATIO3_44_0_
from
MT.METER meter0_
where
meter0_.ID=?
20-04-2018 12:52:49.482 [main] DEBUG o.h.l.p.e.p.i.ResultSetProcessorImpl - Starting ResultSet row #0
20-04-2018 12:52:49.482 [main] DEBUG org.hibernate.SQL -
select
meter0_.ID as ID1_44_0_,
meter0_.FK_K_LSK as FK_K_LSK2_44_0_,
meter0_.FK_METER_LOG as FK_METER_LOG4_44_0_,
meter0_.TRANS_RATIO as TRANS_RATIO3_44_0_
from
MT.METER meter0_
where
meter0_.ID=?
<Skipped>
very strange!
upd2 Meter entity:
#SuppressWarnings("serial")
#Entity
#Table(name = "METER", schema="MT")
#Getter #Setter
public class Meter extends Base implements java.io.Serializable, Storable {
public Meter (){
}
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "ID", updatable = false, nullable = false)
protected Integer id;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name="FK_METER_LOG", referencedColumnName="ID")
private MeterLog meterLog ;
#OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval=true)
#JoinColumn(name="FK_METER", referencedColumnName="ID")
#BatchSize(size = 50)
private List<Vol> vol = new ArrayList<Vol>(0);
#OneToMany(fetch = FetchType.LAZY)
#JoinColumn(name="FK_METER", referencedColumnName="ID")
#BatchSize(size = 50)
private List<MeterExs> exs = new ArrayList<MeterExs>(0);
#Column(name = "TRANS_RATIO", updatable = true, nullable = true)
private Double trRatio;
}

In DTO you have 'Meter meter' field, in meter field you have 'MeterLog meterlog' etc. In this case Hibernate is additionally loading for field for full object. This DTO is to much complex. Try to create more flat object:
public class MeterDTO {
private Integer meterId
private Double meterTrRatio
private Integer lsk;
private Double tp;
(...)
And query will be:
(...) new MeterDTO(m.id, m.trans_ratio, g.kart.lsk (...)
And after that you can extending your DTO for the next fields you want.

The accepted answer suggests changing the DTO, which would not always an acceptable solution.
Here is a solution with no need to change your DTO.
Write your HQL like this:
from Meter m
join m.exs e with m.id=e.meter.id
join m.meterLog g with m.meterLog.id=g.id
join g.kart k with g.kart.id=k.id and :dt between k.dt1 and k.dt2 "
join g.serv s with g.serv.id=s.id "
join k.kw kw with k.kw.id=kw.id "
join kw.house h with kw.house.id=h.id "
(more joins and wheres)
Note that there should not be any select.
getResultList will give you List<Object[]>. Each entry is an array of {Meter, m.exs, m.meterLog, g.kart, ....}. Pick the ones you need and make your MeterDTO.
In my case:
jpa repo
#Query("from Bind bind "
+ "left join Employee employee "
+ "with bind.empCode = employee.empCode "
+ "where bind.accountName = :hiveAccount and bind.disabled = 1 ")
List<Object[]> listMembers(#Param("hiveAccount") String hiveAccount);
DTO
public class BindDTO {
Bind bind;
Employee emp;
public BindDTO(Object[] objs) {
this((Bind) objs[0], (Employee) objs[1]);
}
service
myRepo.listMembers(hiveAccount).stream().map(BindDTO::new).collect(Collectors.toList());

Query In operator in JPQL with CollectionTable

I have CandidateEntity, each CandiadateEntity has multiple job tags. I want to query all CandidateEntity have any job tag in given job tags list. How can I do it with CollectionTable as following code:
query = "SELECT c FROM CandidateEntity c JOIN c.jobFlags f WHERE f in :job_flags"
#ElementCollection(fetch = FetchType.EAGER)
#CollectionTable(name = "job_flags")
#Column(name = "job_flag")
private List<String> jobFlags;
Thanks.

try this:
List<CandidateEntity> candidates= em.createQuery("SELECT c " +
"FROM CandidateEntity c " +
"WHERE :ids IN c.jobFlags")
.setParameter("ids",Arrays.asList(yourList)))
.getResultList();