Im trying to map a oracle db model with JPA entities (Using eclipselink) - i have following simple setup :
table program with primary key id
table multi_kupon with compound primary keys id, spil and foreign key program_id
when i try to fetch program with a simple select i would expect the go get a list
of multi_kupon's but im getting a list of size 0. I've made certain that when i do
a select with joins i get data from both program and multi_kupon.
I believe that its got to do with my relations of the 2 entities - hope somebody can point me to my mistake(s)
Snippet from Entity 'Program' :
#Entity
#Table(name = "PROGRAM", schema = "", catalog = "")
public class Program implements Serializable{
#Id
private Integer id;
private List<MultiKupon> MultiKuponList;
#OneToMany(mappedBy = "program", fetch = FetchType.EAGER)
#JoinColumns({#JoinColumn(name = "id", referencedColumnName = "id"),
#JoinColumn(name = "spil", referencedColumnName = "spil")})
public List<MultiKupon> getMultiKuponList() {
return multiKuponList;
}
Snippet from Entity 'MultiKupon' :
#Entity
#Table(name = "MULTI_KUPON", schema = "", catalog = "")
public class MultiKupon implements Serializable {
private Integer id;
private String spil;
private Program program;
#ManyToOne
public Program getProgram() {
return program;
}
My stateless bean :
#Stateless
public class PostSessionBean {
public Program getProgramById(int programId) {
String programById = "select p from Program p where p.id = :id";
Program program = null;
try {
Query query = em.createQuery(programById);
query.setParameter("id", programId);
program = (Program) query.getSingleResult();
I do get the correcct program entity with data, but the list with
multi_kupon data is size 0
What im i doing wrong here ??
The mapping is incorrect, as you have specified both that the OneToMany is mappedBy = "program" and that it should use join columns. Only one or the other should be used, and since there is a 'program' mapping, I suggest you use:
#OneToMany(mappedBy = "program", fetch = FetchType.EAGER)
public List getMultiKuponList()
And then define the join columns on MultiKupon's ManyToOne mapping to define which fields should be used for the foreign keys to the Program table.
Since you have made this a bidirectional relationship, you must also maintain both sides of your relationship. This means that every time you add a MultiKupon and want it associated to a Program you must both have it reference the Program, AND add the instance to the Program's collection. If you do not, you will run into this situation, where the cached Program is out of sync with what is in the database.
It is much cheaper generally to keep both sides in sync, but if this is not an option, you can correct the issue (or just verify that this is the situation) by calling em.refresh(program). If the mappings are setup correctly, the instance and its list will be repopulated with what is in the database.
According to http://sysout.be/2011/03/09/why-you-should-never-use-getsingleresult-in-jpa/
Try to retrieve first program object of List:
List<Program> pList = query.getResultList();
if(!pList.isEmpty()){
return pList.get(0);
}
Related
I want to get rooms by HospitalId, there relation between classes like it looks below:
#Entity(name = "rooms")
#Table( name = "rooms",
uniqueConstraints = {
#UniqueConstraint(columnNames = "roomNumber")
})
public class Room {
#Id
#GeneratedValue(strategy = GenerationType.TABLE)
private Long idRoom;
private String roomNumber;
#ManyToOne
(fetch = FetchType.EAGER)
#JoinColumn(nullable = false, name = "idhospital")
private Hospital hospital;
this is the query i used :
#Query("select s from rooms s where s.hospital.idHospital =:hospital")
List<Room> findRoomsByHospital( #Param("hospital") Long hospital);
Error in the back :
java.lang.IllegalStateException: Cannot call sendError() after the response has been committed
at org.apache.catalina.connector.ResponseFacade.sendError(ResponseFacade.java:472) ~[tomcat-embed-core-9.0.24.jar:9.0.24]
Is send data but wrong form to the frontend :
error
I really need help can't understand how to deal with it.
I fount the problem :The repitation of data
Solution in to add this notation #JsonIgnore like this :
#ManyToOne
(fetch = FetchType.EAGER)
#JoinColumn(nullable = false, name = "idhospital")
#JsonIgnore
private Hospital hospital;
This is used for to restrict the data to repeat itself
I think you are query is not correct. You have used rooms there without using nativeQuery=true.
you can try below in RoomRepository
#Query("select s from Room s where s.hospital.idHospital =:hospital")
List<Room> findRoomsByHospital( #Param("hospital") Long hospital);
changed rooms to Room
Alternatively, you can try query by a method as shown below, you don't need to use the #Query in this case.
If you are passing hospitalId long use below
List<Room> findRoomsByHospitalIdHospital ( #Param("idHospital") Long hospital);
If you are passing hospital Object use below
List<Room> findRoomsByHospital ( #Param("Hospital ") Hospital hospital);
My User class looks like this :
#Data
#Entity
public class User {
#Id
Long userID;
#ManyToMany(mappedBy = "admins")
private List<ClassRoom> classRooms = new ArrayList<>();
}
And my ClassRoom class like this :
#Data
#Entity
public class ClassRoom {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
Long classRoomID;
#ManyToMany
#JoinTable(name ="classroom_user",
joinColumns = #JoinColumn(name = "classroom_id"),
inverseJoinColumns = #JoinColumn(name = "user_id"))
private List<User> admins = new ArrayList<>();
}
And in my UserController class, I have :
#PostMapping("user/{id}/c")
User addClassRoom(#PathVariable Long id,#RequestBody ClassRoom newClassRoom)
{
logger.debug(repository.findById(id));
return repository.findById(id)
.map(user -> {
user.getClassRooms().add(newClassRoom);
user.setClassRooms(user.getClassRooms());
return repository.save(user);
})
.orElseGet(() -> {
return null;
});
}
And I POST and empty JSON ({}) and I see no change in my users. The Classroom or an empty Classroom doesn't get added in the User.
What is the problem here? How can I resolve this ?
user.getClassRooms().add(newClassRoom); is suffice, user.setClassRooms(user.getClassRooms()); not required.
You will have to perform cascade save operation.List all cascade types explicitly and don't use mappedBy, instead use joincolumns annotation.
Can you paste the logs, please? Is Hibernate doing any insert into your table? Has the database schema been created in the DB correctly? One thing I recommend you to do is to add a custom table name on the top of your User class, using annotations like so: #Table(name = "users"). In most SQL dialects user is a reserved keyword, hence it is recommended to always annotate User class a bit differently, so that Hibernate won't have any problems to create a table for that entity.
IMO you must find classRoom by its id from repository, if it's new, you must create a new entity and save it first. Then assign it to user and save it.
The object you receive from the post method was not created by the entity manager.
After using user.getClassRooms().add(newClassRoom);
We must use userRepository.save(user);
I have an application that teaches the user how to play various card games. The data model that gets persisted consists of a TrainingSession with a uni-directional one-to-many relationship with the Hands.
[EDIT] To clarify, a Hand has no existence outside the context of a TrainingSession (i.e they are created/destroyed when the TrainingSession is). Following the principals of Data Driven Design, the TrainingSession is treated as an aggregate root and therefore a single spring-data CrudRepository is used (i.e., no repository is created for Hand)
When I try to save a TrainingSession using a CrudRepository, I get: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot add or update a child row: a foreign key constraint fails (blackjack.hand, CONSTRAINT FKrpuxac6b80xc7rc98vt1euc3n FOREIGN KEY (id) REFERENCES training_session (tsid))
My problem is the 'save(trainingSession)' operation via the CrudRepository instance. What I don't understand is why the error message states that FOREIGN KEY (id) REFERENCES training_session (tsid)). That seems to be the cause of the problem but I cant figure out why this is the case or how to fix it. The relationship is uni-directional and nothing in the Hand class refers to the TrainingSession.
The code, minus all the getters and setters, is:
#Entity
public class TrainingSession {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Integer tsid;
private String strategy;
#OneToMany(cascade=CascadeType.ALL)
#JoinColumn(name="id")
private List<Hand> hands;
private int userId;
protected TrainingSession() {
}
public TrainingSession(int userId, Strategy strategy, List<Hand> hands) {
this.strategy = strategy.getClass().getSimpleName();
this.hands = hands;
this.userId = userId;
}
while Hand is
#Entity // This tells Hibernate to make a table out of this class
public class Hand {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
private int p1;
private String p1s;
private int p2;
private String p2s;
private int d1;
private String d1s;
private int trials;
private int score;
public Hand() {
}
You need to save your TrainingSession and Hand objects first before saving the adding the hand objects to TrainingSession.
TrainingSession ts1 = new TrainingSession();
trainingSessionManager.save(ts1);
Hand hand1 = new Hand();
handManager.save(hand1);
Hand hand2 = new Hand();
handManager.save(hand2);
ts1.gethands().add(hand1);
ts1.gethands().add(hand2)
trainingSessionManager.save(ts1);
If you check your database you will find 3 tables TrainingSession, Hand and TrainingSession_Hand, The TrainingSession_Hand table references to both TrainingSession and Hand both. Therefore you need to save TrainingSession and hand before saving the relationship.
Found the problem. I was assuming that when spring-data set up the DB tables, it was able to figure out and set up the uni-directional 1-to-many relationship. Apparently that isn't the case. When I configure the relationship as bi-directional everything seems to work.
To fix things I:
removed from TrainingSession the #joincolumn annotation for hands
in Hands I added a TrainingSession field with a #ManyToOne annotation:
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "tsid", nullable = false)
#OnDelete(action = OnDeleteAction.CASCADE)
private TrainingSession tsession;
I also added in the Hand class the getter/setter for tsession
I can now do a save of the entire aggregate construct using only a TrainingSessionRepository.
I am using Spring Data JpaRepository to find List of entities matching a particular field. Consider the following code snippet:
Entity:
#Entity
#Table(name = "master")
#Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
public class Master implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "sequenceGenerator")
#SequenceGenerator(name = "sequenceGenerator")
#Column(name = "id", nullable = false)
private Long Id;
#NotNull
#Column(name = "user_id", nullable = false)
private String userId;
#OneToOne(fetch = FetchType.EAGER)
#JoinColumn(name="id", referencedColumnName="id", insertable=false, updatable=false)
private Details Details;
Spring Data Custom JpaRepository:
public interface MasterRepository extends JpaRepository<Master,Long> {
List<Master> findMasterByUserId(String userId);
}
When i am using findBookingMasterByUserId repository method to find all records with specific user id, I am getting the List of Master entity but I am not getting the Details entity that has id as foreign key in it.
However, I get all the dependent entities when I use out of the box findAll method of JpaRepository but with custom findMasterByUserId repository method, child entities are not being fetched eagerly.
Any type of help would be highly appreciated. Thanks!
You can use #EntityGraph in your repo to eagerly get associated data:
#EntityGraph(attributePaths = {"details"})
List<Master> findBookingMasterByUserId(String userId);
P.S. Don't forget to change 'Details' field to details;
Your entity name is "Master" not "booking_master".
Change your method to:
List<Master> findByUserId(String userId);
Refer to below spring docs for more information on query creation mechanism for JPA.
https://docs.spring.io/spring-data/jpa/docs/current/reference/html/
Alternatively,
#Query("SELECT m FROM Master m WHERE m.userId = :userId")
List<Master> findByUserId(#Param("userId") String userId);
The query generation from the method name is a query generation strategy where the invoked query is derived from the name of the query method.
We can create query methods that use this strategy by following these rules:
The name of our query method must start with one of the following
prefixes: find…By, read…By, query…By, count…By, and get…By.
If we want to limit the number of returned query results, we can add
the First or the Top keyword before the first By word. If we want to
get more than one result, we have to append the optional numeric
value to the First and the Top keywords. For example, findTopBy,
findTop1By, findFirstBy, and findFirst1By all return the first entity
that matches with the specified search criteria.
If we want to select unique results, we have to add the Distinct
keyword before the first By word. For example, findTitleDistinctBy or
findDistinctTitleBy means that we want to select all unique titles
that are found from the database.
We must add the search criteria of our query method after the first
By word. We can specify the search criteria by combining property
expressions with the supported keywords.
If our query method specifies x search conditions, we must add x
method parameters to it. In other words, the number of method
parameters must be equal than the number of search conditions. Also,
the method parameters must be given in the same order than the search
conditions.
I am implementing queries in my web application with JPA repositories. The two main tables I am querying from are FmReportTb and SpecimenTb.
Here are the two entity classes (only important attributes are listed).
//FmReportTb.java
#Entity
#Table(name="FM_REPORT_TB")
public class FmReportTb implements Serializable {
#Column(name="ROW_ID")
private long rowId;
#Column(name="FR_BLOCK_ID")
private String frBlockId;
#Column(name="FR_FULL_NAME")
private String frFullName;
#OneToOne
#JoinColumn(name="SPECIMEN_ID")
private SpecimenTb specimenTb;
FmReportTb has OneToOne relationship with SpecimenTb.
#Entity
#Table(name="SPECIMEN_TB")
public class SpecimenTb implements Serializable {
private String mrn;
#OneToOne(mappedBy="specimenTb", cascade=CascadeType.ALL)
private FmReportTb fmReportTb;
The query I am working on is to find all records in FmReportTb and show a few attributes from FmReportTb plus mrn from SpecimenTb.
Here is my JPA repository for FmReportTb:
#Repository
public interface FmReportRepository extends JpaRepository<FmReportTb, Long> {
#Query("select f from FmReportTb f where f.deleteTs is not null")
public List<FmReportTb> findAllFmReports();
Since, I am only showing part of the attributes from FmReportTb and one attribute from SpecimenTb, I decided to create a Value Object for FmReportTb. The constructor of the VO class assigns attributes from FmReportTb and grabs mrn attribute from SpecimenTb based on the OneToOne relationship. Another reason for using VO is because table FmReportTb has a lot of OneToMany children entities. For this particular query, I don't need any of them.
public class FmReportVO {
private String frBlockId;
private Date frCollectionDate;
private String frCopiedPhysician;
private String frDiagnosis;
private String frFacilityName;
private String frFullName;
private String frReportId;
private String filepath;
private String mrn;
public FmReportVO(FmReportTb fmReport) {
this.frBlockId = fmReport.getFrBlockId();
this.frCollectionDate = fmReport.getFrCollectionDate();
this.frCopiedPhysician = fmReport.getFrCopiedPhysician();
this.frDiagnosis = fmReport.getFrDiagnosis();
this.frFacilityName = fmReport.getFrFacilityName();
this.frFullName = fmReport.getFrFullName();
this.frReportId = fmReport.getFrReportId();
this.mrn = fmReport.getSpecimenTb().getMrn();
}
I implemented findall method in servicebean class to return a list of FmReportTb VOs.
//FmReportServiceBean.java
#Override
public List<FmReportVO> findAllFmReports() {
List<FmReportTb> reports = fmReportRepository.findAllFmReports();
if (reports == null) {
return null;
}
List<FmReportVO> fmReports = new ArrayList<FmReportVO>();
for (FmReportTb report : reports) {
FmReportVO reportVo = new FmReportVO(report);
String filepath = fileLoadRepository.findUriByFileLoadId(report.getFileLoadId().longValue());
reportVo.setFilepath(filepath);
fmReports.add(reportVo);
}
return fmReports;
}
Lastly, my controller looks like this:
#RequestMapping(
value = "/ristore/foundation/",
method = RequestMethod.GET,
produces = "application/json")
public ResponseEntity<List<FmReportVO>> getAllFmReports() {
List<FmReportVO> reports = ristoreService.findAllFmReports();
if (reports == null) {
return new ResponseEntity<List<FmReportVO>>(HttpStatus.NOT_FOUND);
}
return new ResponseEntity<List<FmReportVO>>(reports, HttpStatus.OK);
}
There are about 200 records in the database. Surprisingly, it took almost 2 full seconds to retrieve all the records in JSON. Even though I did not index all the tables, this is way too slow. Similar query takes about probably a few ms on the database directly. Is it because I am using Value Objects or JPA query tends to be this slow?
EDIT 1
This may have to do with the fact that FmReportTb has almost 20 OneToMany entities. Although the fetchmode of these child entities are set to LAZY, JPA Data repository tends to ignore the fetchmode. So I ended up using NamedEntityGraph to specify the attributes EAGER. This next section is added to the head of my FmReportTb entity class.
#Entity
#NamedEntityGraph(
name = "FmReportGraph",
attributeNodes = {
#NamedAttributeNode("fileLoadId"),
#NamedAttributeNode("frBlockId"),
#NamedAttributeNode("frCollectionDate"),
#NamedAttributeNode("frDiagnosis"),
#NamedAttributeNode("frFullName"),
#NamedAttributeNode("frReportId"),
#NamedAttributeNode("specimenTb")})
#Table(name="FM_REPORT_TB")
And then #EntityGraph("FmReportGraph") was added before the JPA repository query to find all records. After doing that, the performance is improved a little bit. Now fetching 1500 records only takes about 10 seconds. However, it still seems too slow given each json object is fairly small.
Answering for the benefit of others with slow JPA queries...
As #Ken Bekov hints in the comments, foreign keys can help a lot with JPA.
I had a couple of tables with a many to one relationship - a query of 100,000 records was taking hours to perform. Without any code changes I reduced this to seconds just by adding a foreign key.
In phpMyAdmin you do this by creating a Relationship from the "many" table to the "one" table. For a detailed explanation see this question: Setting up foreign keys in phpMyAdmin?
and the answer by #Devsi Odedra