I read that It is not a good practice to put #Scheduled and #Transactional annotation together because of the Spring default AOP implementation. (proxy classes etc.)
I have decided to try it by myself and I created a very short app for testing but surprisingly my code works when I put these things together and also when I created a separated Schedule service for the annotation.
#Entity
class AEntity(
#OneToMany(mappedBy = "aEntity", fetch = FetchType.LAZY, cascade = [CascadeType.REMOVE])
var bEntities: MutableSet<BEntity>? = null,
#Id #GeneratedValue var id: Long? = null
)
#Entity
class BEntity(
#ManyToOne
#JoinColumn(name = "a_entity_id", referencedColumnName = "id")
var aEntity: AEntity,
#Id #GeneratedValue var id: Long? = null
)
Service:
#Service
class AService(val aRepository: ARepository) {
#Scheduled(fixedRate = 5000)
#Transactional
fun test() {
val aEntity = aRepository.findOneById(1)
aEntity?.bEntities?.forEach {
println(it.id)
}
}
}
You can reach my full project from here
Related
I need to implement categories and subcategories within my entities. Here's what I have so far and think it should be:
StockCategory.kt
#Entity
#Table(name = "table_categories")
data class StockCategory(
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "category_id")
val id: Long? = null,
#ManyToOne
#JoinColumn(name = "parentid")
val parent: StockCategory? = null,
#ManyToMany(mappedBy = "categories")
var stockItems: MutableList<StockItem> = mutableListOf(),
#OneToMany(mappedBy = "parent")
var childCategories: MutableList<StockCategory> = mutableListOf(),
)
StockItem.kt
#Entity
#Table(name = "table_stock")
data class StockItem(
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "stock_item_id")
val id: Long? = null,
#Column(name = "stock_item_name")
var name: String = "New Item",
...
#ManyToMany
#JoinColumn(name = "item_category", referencedColumnName = "category_id")
var categories: MutableList<StockCategory> = mutableListOf(),
...
)
Now at the moment, this looks to be correct... At the very least Spring Boot is not complaining.
However, in terms of what to do next, I'm not sure. I know I need to implement a JpaRepository, of which I have the current:
StockCategoryRepository.kt
interface StockCategoryRepository: JpaRepository<StockCategory, Long> {
}
I also need to implement the relevant methods in my service class.
What exactly do I need to do next in order to get this to work and be able to use the information later on? Please also ELI5 too as although I have a decent amount of knowledge on this, I'm still not where I would like to be when it comes to this.
A few background bits if it makes it easier for you.
I'm using H2 as my database, Spring Boot and Kotlin as my language.
I have three Hibernate #Entity's below that mimic a failure in my production app:
#Entity
#Data
#SuperBuilder(toBuilder = true)
#EqualsAndHashCode(callSuper = true)
#NoArgsConstructor
#AllArgsConstructor
public class Dog extends Animal {
String barkType;
}
The Dog entity uses JOINED inheritance with this class, Animal:
#Entity
#Inheritance(strategy = InheritanceType.JOINED)
#Data
#SuperBuilder(toBuilder = true)
#NoArgsConstructor
#AllArgsConstructor
public class Animal {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Type(type = "uuid-char")
private UUID id;
#OneToMany(cascade = CascadeType.REMOVE)
#JoinColumn(name = "animalId", referencedColumnName = "id", insertable = false, updatable = false)
#Builder.Default
private List<Toy> toys = new ArrayList<>();
}
This Toy Entity is related to the parent class, Animal
#Entity
#Data
#Builder
#NoArgsConstructor
#AllArgsConstructor
public class Toy {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Type(type = "uuid-char")
private UUID id;
#Type(type = "uuid-char")
private UUID animalId;
private String shape;
}
And here is my implementation I am testing:
#Service
#AllArgsConstructor
public class DogService {
DogRepository repository;
ToyRepository toyRepository;
#Transactional
public Dog saveDogDTO(DogDTO dogDTO) {
Dog entity = Dog.builder()
.barkType(dogDTO.getBarkType())
.build();
repository.save(entity);
toyRepository.save(Toy.builder()
.shape(dogDTO.getToyShape())
.animalId(entity.getId())
.build());
return entity;
}
}
Here is my failing Test, which fails on the LAST line:
#DataJpaTest
class DogServiceTests {
private DogService dogService;
#Autowired
private DogRepository dogRepository;
#Autowired
private ToyRepository toyRepository;
#Test
void save_not_working_example() {
dogService = new DogService(dogRepository, toyRepository);
var dogDTO = DogDTO.builder()
.barkType("big bark")
.toyShape("some shape")
.build();
var savedDog = dogService.saveDogDTO(dogDTO);
assertThat(dogRepository.count()).isEqualTo(1);
assertThat(toyRepository.count()).isEqualTo(1);
var findByIdResult = dogRepository.findById(savedDog.getId());
assertThat(findByIdResult.get().getToys()).hasSize(1);
}
}
The test failure message:
Expected size: 1 but was: 0 in:
[]
java.lang.AssertionError:
Expected size: 1 but was: 0 in:
[]
The issue seems to be that the double JPA repository save clashes within the #Transaction. Is there a way to overcome this issue? I tried adding #Transactional(propagation = Propagation.NEVER) to the test, but then I get this failure:
failed to lazily initialize a collection of role: com.example.datajpatest.demo.models.Animal.toys, could not initialize proxy - no Session
org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.example.datajpatest.demo.models.Animal.toys, could not initialize proxy - no Session
#DataJpaTest is annotated #Transactional so your test method is all wrapped in a single transaction, and hence a single EntityManager. You could make your test pass by calling EntityManager.detach() on the savedDog before querying using findById(). You could also fix it by manually setting up the dog's toys in the DogService. That would be my recommendation because otherwise sooner or later you might find the same inconsistency bug in production code - the transaction boundaries just have to shift a bit and that would be quite hard to spot. In a way #DataJpaTest has done you a favour by pointing out the problem, albeit somewhat indirectly.
Ultimately, the database state doesn't match the state of the EntityManager cache, so you have to clear the cache to get the result you want. Starting a new transaction would clear the cache too, and that's what is probably happening in production. Hibernate trusts you to make the object graph match the database state when you save (or flush). If they don't match then Hibernate has no way of knowing without querying the database, which it would regard as redundant and inefficient.
Try this mapping here instead:
#Entity
#Inheritance(strategy = InheritanceType.JOINED)
#Data
#SuperBuilder(toBuilder = true)
#NoArgsConstructor
#AllArgsConstructor
public class Animal {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Type(type = "uuid-char")
private UUID id;
#OneToMany(mappedBy = "animal", cascade = CascadeType.REMOVE)
#Builder.Default
private List<Toy> toys = new ArrayList<>();
}
#Entity
#Data
#Builder
#NoArgsConstructor
#AllArgsConstructor
public class Toy {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Type(type = "uuid-char")
private UUID id;
#ManyToOne(fetch = LAZY)
#JoinColumn(name = "animalId")
private Animal animal;
private String shape;
}
Spring Boot, Hibernate, bidirectional One-To-Many. Strange behavior. Why is there two selects instead of an error?
I have a basic Spring boot application.
It simulates throwing dices.
I have two entity classes Dice and DiceBatch.
DiceBatch has List<Dice> dices;
Dice has DiceBatch diceBatch; as two sides of bidirectional ManyToOne, or OneToMany.
I use JpaRepository<DiceBatch, UUID> to get one instance of DiceBatch by callig a method of JpaRepository findById(UUID id)
I call this method inside DiceBatchService's method findDiceBatchById(UUID diceBatchId).
Method is marked as #Transactional.
When i do that Hibernate logs one SQL select:
/* select
d
from
DiceBatch d
where
d.id = ?1 */ select
dicebatch0_.dice_batch_id as dice_bat1_1_,
dicebatch0_.batch_creation_time as batch_cr2_1_,
dicebatch0_.batch_name as batch_na3_1_
from
dice_batch dicebatch0_
where
dicebatch0_.dice_batch_id=?
At this point everything is ok.
Method returns DiceBatch entity with lazily initialized List<Dice> dices.
This is important. Method is #Transactional when method returns I should leave transactionla context.
Lazy fields should stay lazy and should cause LazyInitializationException if I try to access them.
Now control goes back to the controller method of DiceBatchController findDiceBatchById(UUID diceBatchId)
And here something strange happens.
Hibernate logs another select
select
dices0_.dice_batch_id as dice_bat5_0_0_,
dices0_.dice_id as dice_id1_0_0_,
dices0_.dice_id as dice_id1_0_1_,
dices0_.dice_batch_id as dice_bat5_0_1_,
dices0_.sequential_number as sequenti2_0_1_,
dices0_.throw_result as throw_re3_0_1_,
dices0_.throw_time as throw_ti4_0_1_
from
dice dices0_
where
dices0_.dice_batch_id=?
...and response JSON contains DiceBatch with all Dice entities related to it.
So I have several question.
Why didn't I get LazyInitializationException?
How come the List<Dice> inside DiceBatch got initialized outside of Transactional context?
How Spring managed to build a complete entity of DiceBatch, including the content of the List<Dice> without any exceptions?
How to modify my code to avoid this strange implicit bahavior?
Here is all the relevant code.
package org.dice.model;
#Entity
#Builder
#Getter
#Setter
#NoArgsConstructor
#AllArgsConstructor
public class Dice {
#Id
#GenericGenerator(name = "UUID",
strategy = "org.hibernate.id.UUIDGenerator")
#GeneratedValue(strategy = javax.persistence.GenerationType.AUTO,
generator = "UUID")
#Column(name = "dice_id",
nullable = false)
private UUID id;
#Column(name = "throw_result",
nullable = false)
private Integer throwResult;
#Column(name = "throw_time",
nullable = false)
private LocalDateTime throwTime;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "dice_batch_id",
nullable = false,
foreignKey = #ForeignKey(name = "fk_dice_dice_batch_id_dice_batch_dice_batch_id")
)
#JsonBackReference
private DiceBatch diceBatch;
#Embedded
private SequentialNumber sequentialNumber;
}
package org.dice.model;
#Entity
#Builder
#Getter
#Setter
#NoArgsConstructor
#AllArgsConstructor
public class DiceBatch {
#Id
#GenericGenerator(name = "UUID",
strategy = "org.hibernate.id.UUIDGenerator")
#GeneratedValue(strategy = GenerationType.AUTO,
generator = "UUID")
#Column(name = "dice_batch_id",
nullable = false)
private UUID id;
#Column(name = "batch_name",
nullable = false)
private String batchName;
#Column(name = "batch_creation_time",
nullable = false)
private LocalDateTime batchCreationTime;
#OneToMany(
mappedBy = "diceBatch",
cascade = CascadeType.ALL,
orphanRemoval = true,
fetch = FetchType.LAZY)
#JsonManagedReference
private List<Dice> dices = new ArrayList<>();
public void addDice(Dice dice) {
dices.add(dice);
dice.setDiceBatch(this);
}
public void removeDice(Dice dice) {
dices.remove(dice);
dice.setDiceBatch(null);
}
}
package org.dice.repo;
#Repository
public interface DiceBatchRepo extends JpaRepository<DiceBatch, UUID> {}
package org.dice.service;
#Service
#RequiredArgsConstructor
public class DiceBatchService {
#Transactional
public DiceBatch findDiceBatchById(UUID diceBatchId) {
DiceBatch diceBatch = diceBatchRepo
.findById_my(diceBatchId)
.orElseThrow();
return diceBatch;
}
}
package org.dice.controller;
public class DiceBatchController {
#GetMapping(path = "/get/{diceBatchId}")
public ResponseEntity<DiceBatch> findDiceBatchById(
#PathVariable(name = "diceBatchId") UUID diceBatchId) {
log.info("<C>[/batch/get] endpoint reached.\n" +
"Dice Batch Id: {}\n",
diceBatchId);
return ResponseEntity.ok(diceBatchService.findDiceBatchById(diceBatchId));
}
}
I'm creating a test and basically doing different transactions inside a #Transactional method.
I add a Project, then add a Task to it, and last will fetch the project again from DB to test it has the task saved.
Please note the case I'm showing is a unit test but I'm more interesting in fixing the transactional methods and not the test itself as I already had this in the past in "production code".
Model Classes:
#Entity
#Table(name = "Task")
data class Task(
#Id
#SequenceGenerator(name = "TaskSeq", sequenceName = "TaskSeq", initialValue = 100)
#GeneratedValue(generator = "TaskSeq")
val id: Long = 0,
#Column(nullable = false)
val name: String,
val description: String,
val inZ: LocalDateTime = LocalDateTime.now(),
var outZ: LocalDateTime = JpaConstants.MAX_DATETIME,
var completed: Boolean = false,
#ManyToOne(cascade = [CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH])
#JoinColumn(name = "projectId")
var project: Project? = null
) {
}
#Entity
#Table(name = "Project")
data class Project(
#Id
#SequenceGenerator(name = "ProjectSeq", sequenceName = "ProjectSeq", initialValue = 100)
#GeneratedValue(generator = "ProjectSeq")
val id: Long = 0,
#Column(nullable = false)
var name: String,
#OneToMany(mappedBy = "project", cascade = [CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH])
val tasks: MutableList<Task> = Lists.mutable.empty()
) {
}
Service Classes:
#Service
class ProjectServiceImpl(private val projectRepository: ProjectRepository) : ProjectService {
override fun save(project: Project): Project {
return projectRepository.save(project)
}
}
#Service
class TaskServiceImpl(private val taskRepository: TaskRepository, private val projectRepository: ProjectRepository) : TaskService {
override fun save(task: Task): Task {
return taskRepository.save(task)
}
override fun addTaskToProject(projectId: Long, task: Task): Task {
val project = projectRepository.findById(projectId).orElseThrow { RecordNotFoundException("Couldn't find project with id {$projectId}") }
task.project = project
return save(task)
}
}
The class I'm trying to use the transactional method:
class TaskServiceImplTest : TaskApplicationTests() {
#Autowired
private lateinit var taskService: TaskService
#Autowired
private lateinit var taskRepository: TaskRepository
#Autowired
private lateinit var projectService: ProjectService
#Test
#Transactional
fun canInsertTaskToProject() {
val project = projectService.save(Project(name = "Conquer Paris"))
var task = Task(name = "Check how many people we need to hire", description = "")
task = taskService.addTaskToProject(project.id, task)
assertTrue(task.id > 0)
val projects = projectService.findAll()
assertEquals(1, projects.size())
assertEquals(1, projects[0].tasks.size)
assertEquals(task.id, projects[0].tasks[0].id)
}
If I add a #Transactional(REQUIRES_NEW) to the methods in the service it will work, but I don't want it as if this method is called inside a real transaction I want it to be rolled back accordingly. Also I'd like to avoid using too many REQUIRES_NEW to avoid future problems
If I remove the #Transactional from the test method, it won't work when I test the size of the task list on last two lines as they are lazy.
What is the best way to make it work ? I thought that inside a #Transactional when I used another command from db it would get the latest updates that were not committed yet..
If needed, code in Java is fine too :)
Thanks in advance!
Based on your scenarios, you can use #TestEntityManagerso that each test can be managed in transaction context.
This example can help you,
https://grokonez.com/testing/datajpatest-with-spring-boot
I have a project with Spring Boot, and I cannot make lazy loading work. I have 2 entities: Question and Answer. A question can have many answers.
What I want is, when I try to get an answer, to get only the answer without the question. And also, if I want both, to have this possibility.
What I did, is I added in application.yml: spring.jpa.open-in-view: true.
The Answer entity is like:
#Entity
#Table(name = "mst_ans_answer", schema = "lquest_sc")
public class Answer implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "lquest_sc.mst_ans_answer_ans_lqs_id_seq")
#SequenceGenerator( name = "lquest_sc.mst_ans_answer_ans_lqs_id_seq", sequenceName = "lquest_sc.mst_ans_answer_ans_lqs_id_seq")
#Column(name = "ans_lqs_id")
private int id;
#Column(name = "qst_lqs_id")
private int questionId;
#Column(name = "ans_text")
private String text;
#ManyToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY, optional = false)
#JoinColumn(name = "qst_lqs_id", insertable=false, updatable=false)
#JsonIgnore
private Question question;
//getters and setters
}
The Question entity is:
#Entity
#Table(name = "mst_qst_question", schema = "lquest_sc")
public class Question implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "lquest_sc.mst_qst_question_qst_lqs_id_seq")
#SequenceGenerator(name = "lquest_sc.mst_qst_question_qst_lqs_id_seq", sequenceName = "lquest_sc.mst_qst_question_qst_lqs_id_seq")
#Column(name = "qst_lqs_id")
private int id;
#Column(name = "qst_title")
private String title;
#OneToMany(fetch = FetchType.LAZY, mappedBy = "question")
#OrderBy("order asc")
private Set<Answer> answers = new HashSet<Answer>();
//getters and setters here
The call in the controller is:
#RequestMapping(value = "/questionId/{id}", method = RequestMethod.GET)
public List<Answer> listAll( #PathVariable("id") int id ){
List<Answer> answers = answerRepository.findByEnabledAndQuestionIdOrderByOrderAsc(1,id);
return answers;
}
and the repository is
public interface AnswerRepository extends JpaRepository<Answer, Long> {
List<Answer> findByEnabledAndQuestionIdOrderByOrderAsc(int enabled,int questionId);
}
The problem is that in the controller, when I try to evaluate
answers.get(0).getQuestion(), I receive the entity of Question, with the properties filled with null values and the error Method threw 'org.hibernate.LazyInitializationException' exception. Cannot evaluate Question_$$_jvst5b6_1.toString(). What am I doing wrong?
I don't know why spring.jpa.open-in-view = true is not working in your case. Maybe the OpenEntityManagerInViewInterceptordoes not get triggered or the thread has been left, when you are evaluating the Question. Or you have an older version which just does not support it.
Lazy loading works only inside of a transaction. A solution could be -
as #Pradeep already gave you the hint - to use #Tranactional inside a business logic class.
Even if you put the #Transactional inside your repository it will not work, because you have to put the annotation on top of the method where you are trying to evaluate answers.get(0).getQuestion().
Furthermore I advise you not to call your repository from the controller directly, but to use a service layer, where you put your business logic.
Example implementation
This is only a example implementation to show you how to structure your application and what the important keywords are. Also note, that you can either use #Inject or #Autowired. When you have implemented your logic, just inject the service into your controller and use it there.
AnswerService.java
public interface AnswerService {
List<Answer> findByEnabledAndQuestionIdOrderByOrderAsc(int enabled, Long id);
}
AnswerServiceImpl.java
#Service
public class AnswerServiceImpl implements AnswerService {
private AnswerRepository answerRepository;
#Inject
public AnswerServiceImpl(AnswerRepository answerRepository) {
this.answerRepository = answerRepository;
}
#Transactional
#Override
public List<Answer> findByEnabledAndQuestionIdOrderByOrderAsc(int enabled, Long id) {
List<Answer> answerList = findByEnabledAndQuestionIdOrderByOrderAsc(int enabled,int questionId);
// do your lazy loading here
// because you are still in the same transactional context
// return the list
return answerList;
}
}