I am creating a simple spring application which is supposed to book seats in a seminar. Lets say Booking class looks like this
#Entity
#Table(name = "bookings")
#IdClass(BookingId.class)
public class Booking{
#Id
private Long seminarId;
#Id
private String seatNo;
// .. other fields like perticipant info
// .. getter setters
}
of course the BookingId class:
public class BookingId implements Serializable{
private static final long serialVersionUID = 1L;
private Long seminarId;
private String seatNo;
// .. constructors, getters, setters
}
And I have a repository
#Repository
public interface BookingsRepository extends JpaRepository<Booking, BookingId>{
}
in the controller when a booking request arrives I first check if a booking with same seminer id and seat number already exists, if it doesn't exist I create one
#RequestMapping(method = RequestMethod.POST)
public ResponseEntity<BaseCrudResponse> createNewBooking(#Valid #RequestBody NewBookingDao newBookingDao, BindingResult bindingResult){
logger.debug("Request for a new booking");
// .. some other stuffs
Booking newBooking = new Booking();
newBooking.setSeminarId(newBookingDao.getSeminarId());
newBooking.setSeatNumber(newBookingDao.getSeatNumber());
// .. set other fields
Booking existing = bookingsRepository.findOne(new BookingId(newBooking.getSeminarId(), newBooking.getSeatNumber());
if (existing == null)
bookingsRepository.save(newBooking);
return new ResponseEntity<>(new BaseCrudResponse(0), HttpStatus.CREATED);
}
return new ResponseEntity<>(response, HttpStatus.BAD_REQUEST);
}
Now what will happen if the save method of the repository didn't finish commiting transaction and another request already gets past the existence check ? There might be incorrect booking (the last commit will override the previous). Is this scenario likely to happen ? Will the repository ensures that it completes the transaction before another save call ?
Also is there any way to tell Jpa to throw some exception (for IntegrityConstraintException if the composite key (in this case seminerId and seatNumber) already exists ? Now in the present setting its just updating the row.
You can use javax.persistence.LockModeType.PESSIMISTIC_WRITE so other transactions except the one that got the lock cannot update the entity.
If you use spring-data > 1.6 you can annotate the repository method with #Lock :
interface BookingsRepository extends Repository<Booking, Long> {
#Lock(LockModeType.PESSIMISTIC_WRITE)
Booking findOne(Long id);
}
For sure you need to handle the locking exception that may be thron in the controller.
Related
I have a scenario where I am consuming an event and saving the details in the DB. Now the record that is being stored in the database has the id field autogenerated #GeneratedValue(strategy = GenerationType.IDENTITY).
In my test case I need to check if data is getting stored in the DB or not and is as per expectation.
But I am not sure how will I do findById() of SpringBoot Crud/JPA Repository since I do not know what value got generated.
Any help would be appreciated.
Take a look at save method from CrudRepository interface. Spring executes this method in transaction and after its completion Hibernate will generate identifier in returned entity.
Suppose your entity and repository looks as following:
....
public class SomeEntity {
#Id
#GeneratedValue
private Long id;
private String name;
public SomeEntity(String name){
this.name = name;
}
....
}
public interface SomeRepository extends CrudRepository<SomeEntity, Long> {
}
After saving entity:
SomeEntity someEntity = someRepository.save(new SomeEntity("Some entity"));
someEntity.getId() will contain actual record id which can be used further in your tests.
I think you are looking for annotation #DirtiesContext .
It is a Test annotation which indicates that the ApplicationContext associated with a test is dirty and should therefore be closed and removed from the context cache. - javadoc
Read Section 9.3.4 - Here
Check - Example ans below as well:
#Test
#DirtiesContext
public void save_basic() {
// get a course
Course course = courseJpaRepository.findById(10001L);
assertEquals("JPA ", course.getName());
// update details
course.setName("JPA - Updated");
courseJpaRepository.saveOrUpdate(course);
// check the value
Course course1 = courseJpaRepository.findById(10001L);
assertEquals("JPA - Updated", course1.getName());
}
BTW - how you can get the id : simply via getter method from the return type of save
EmployeeDetails employeeDetails = emaployeeService.saveEmployeeDetails(employee);
int temp = employeeDetails.getID()
Related Post : Here
`
#Service
#Transactional
Public class UserService
public void saveUser()
User userEntity = new User();
userEntity.setName("test");
User userDataFromDB = userRepository.save(userEntity);
LOG.info("user Id= " +userDataFromDB.getId());
//entity code below
#Id
#GeneratedValue(strategy =
GenerationType.IDENTITY)
#Column(name="ID")
private int id;
#Column(name="NAME")
private string name;`
not able to get the saved Id of user only after using transactional annotation else getting the id after removing transactional annotation . Any help would be appreciable.
Change as below:
public void saveUser()
User userEntity = new User();
userEntity.setName("test");
userRepository.saveAndFlush(userEntity); //force immediate db write
LOG.info("user Id= " + userEntity.getId());
}
Typically database updates will not be flushed until your #Transactional method returns. By using saveAndFlush(e) (which delegates to EntityManager#flush
- What does EntityManager.flush do and why do I need to use it?) you can force the database update to happen immediately.
As an aside, for or a newly persistent entity the save(e) or saveAndFlush(e) method calls simply return e so no need to assign the returned result to another variable.
I have a database with one table named person:
id | first_name | last_name | date_of_birth
----|------------|-----------|---------------
1 | Tin | Tin | 2000-10-10
There's a JPA entity named Person that maps to this table:
#Entity
#XmlRootElement(name = "person")
#XmlAccessorType(NONE)
public class Person {
#Id
#GeneratedValue
private Long id;
#XmlAttribute(name = "id")
private Long externalId;
#XmlAttribute(name = "first-name")
private String firstName;
#XmlAttribute(name = "last-name")
private String lastName;
#XmlAttribute(name = "dob")
private String dateOfBirth;
// setters and getters
}
The entity is also annotated with JAXB annotations to allow XML payload in
HTTP requests to be mapped to instances of the entity.
I want to implement an endpoint for retrieving and updating an entity with a given id.
According to this answer to a similar question,
all I need to do is to implement the handler method as follows:
#RestController
#RequestMapping(
path = "/persons",
consumes = APPLICATION_XML_VALUE,
produces = APPLICATION_XML_VALUE
)
public class PersonController {
private final PersonRepository personRepository;
#Autowired
public PersonController(final PersonRepository personRepository) {
this.personRepository = personRepository;
}
#PutMapping(value = "/{person}")
public Person savePerson(#ModelAttribute Person person) {
return personRepository.save(person);
}
}
However this is not working as expected as can be verified by the following failing test case:
#RunWith(SpringRunner.class)
#SpringBootTest(webEnvironment = RANDOM_PORT)
public class PersonControllerTest {
#Autowired
private TestRestTemplate restTemplate;
private HttpHeaders headers;
#Before
public void before() {
headers = new HttpHeaders();
headers.setContentType(APPLICATION_XML);
}
// Test fails
#Test
#DirtiesContext
public void testSavePerson() {
final HttpEntity<Object> request = new HttpEntity<>("<person first-name=\"Tin Tin\" last-name=\"Herge\" dob=\"1907-05-22\"></person>", headers);
final ResponseEntity<Person> response = restTemplate.exchange("/persons/1", PUT, request, Person.class, "1");
assertThat(response.getStatusCode(), equalTo(OK));
final Person body = response.getBody();
assertThat(body.getFirstName(), equalTo("Tin Tin")); // Fails
assertThat(body.getLastName(), equalTo("Herge"));
assertThat(body.getDateOfBirth(), equalTo("1907-05-22"));
}
}
The first assertion fails with:
java.lang.AssertionError:
Expected: "Tin Tin"
but: was "Tin"
Expected :Tin Tin
Actual :Tin
In other words:
No server-side exceptions occur (status code is 200)
Spring successfully loads the Person instance with id=1
But its properties do not get updated
Any ideas what am I missing here?
Note 1
The solution provided here is not working.
Note 2
Full working code that demonstrates the problem is provided
here.
More Details
Expected behavior:
Load the Person instance with id=1
Populate the properties of the loaded person entity with the XML payload using Jaxb2RootElementHttpMessageConverter or MappingJackson2XmlHttpMessageConverter
Hand it to the controller's action handler as its person argument
Actual behavior:
The Person instance with id=1 is loaded
The instance's properties are not updated to match the XML in the request payload
Properties of the person instance handed to the controller's action handler method are not updated
this '#PutMapping(value = "/{person}")' brings some magic, because {person} in your case is just '1', but it happens to load it from database and put to ModelAttribute in controller. Whatever you change in test ( it can be even empty) spring will load person from database ( effectively ignoring your input ), you can stop with debugger at the very first line of controller to verify it.
You can work with it this way:
#PutMapping(value = "/{id}")
public Person savePerson(#RequestBody Person person, #PathVariable("id") Long id ) {
Person found = personRepository.findOne(id);
//merge 'found' from database with send person, or just send it with id
//Person merged..
return personRepository.save(merged);
}
wrong mapping in controller
to update entity you need to get it in persisted (managed) state first, then copy desired state on it.
consider introducing DTO for your bussiness objects, as, later, responding with persisted state entities could cause troubles (e.g. undesired lazy collections fetching or entities relations serialization to XML, JSON could cause stackoverflow due to infinite method calls)
Below is simple case of fixing your test:
#PutMapping(value = "/{id}")
public Person savePerson(#PathVariable Long id, #RequestBody Person person) {
Person persisted = personRepository.findOne(id);
if (persisted != null) {
persisted.setFirstName(person.getFirstName());
persisted.setLastName(person.getLastName());
persisted.setDateOfBirth(person.getDateOfBirth());
return persisted;
} else {
return personRepository.save(person);
}
}
Update
#PutMapping(value = "/{person}")
public Person savePerson(#ModelAttribute Person person, #RequestBody Person req) {
person.setFirstName(req.getFirstName());
person.setLastName(req.getLastName());
person.setDateOfBirth(req.getDateOfBirth());
return person;
}
The issue is that when you call personRepository.save(person) your person entity does not have the primary key field(id) and so the database ends up having two records with the new records primary key being generated by the db. The fix will be to create a setter for your id field and use it to set the entity's id before saving it:
#PutMapping(value = "/{id}")
public Person savePerson(#RequestBody Person person, #PathVariable("id") Long id) {
person.setId(id);
return personRepository.save(person);
}
Also, like has been suggested by #freakman you should use #RequestBody to capture the raw json/xml and transform it to a domain model. Also, if you don't want to create a setter for your primary key field, another option may be to support an update operation based on any other unique field (like externalId) and call that instead.
For updating any entity the load and save must be in same Transaction,else it will create new one on save() call,or will throw duplicate primary key constraint violation Exception.
To update any we need to put entity ,load()/find() and save() in same transaction, or write JPQL UPDATE query in #Repository class,and annotate that method with #Modifying .
#Modifying annotation will not fire additional select query to load entity object to update it,rather presumes that there must be a record in DB with input pk,which needs to update.
I seem to be baffled on how JPA Repositories are suppose to work.
In a nut-shell
#Entity
public class User extends AbstractEntity {
protected final static String FK_NAME = "USER_ID";
#Column(nullable = false)
private String firstName;
#OneToMany(cascade = ALL, fetch = FetchType.LAZY, orphanRemoval = true)
#JoinColumn(name = "userId")
private List<Detail> details = new ArrayList<Detail>();
}
#Entity
public class Detail extends AbstractEntity {
Long userId;
String hello;
}
#Repository
public interface UserRepository extends CrudRepository<User, Long> {
User findByFirstName(#Param("firstName") String firstName);
}
And here is the only controller in the app:
#RestController
public class Home {
#Autowired
UserRepository userRepository;
#Autowired
DetailsRepository loanRepository;
#RequestMapping(value = "")
public HttpEntity home() {
User user = userRepository.findByFirstName("John");
if (user == null) {
user = new User();
user.setFirstName("John");
}
Detail detail = new Detail();
detail.setHello("Hello Msh");
user.getDetails().add(detail);
userRepository.save(user);
return new ResponseEntity("hi", HttpStatus.OK);
}
}
Below a screenshot from debugging session where the app just started and the get request to home() method creates new user, new detail, adds detail to user.
Below example - when the user is saved, the detail entity gets updated
Now on the next request, the old user John is found and has been added a new instance of detail.
The old user has been saved but now the newly created detail does not get updated outside.
How come this only works first time ?
Basically theres so much fail going on so that I would advise you to go a step backwards. If youre wana go the short path of getting a solution for exactly this problem continue reading ;)
First part related to the answer of Jaiwo99:
As I can see in the gradle view of intellij, your using Spring Boot. So it is necessary to place #EnableTransactionManagement on top of your configuration class. Otherwise the #Transacion annotation does not have any effect.
Second part your JPA/Hibernate model mapping. Theres so much bad practise on the net that it is no wonder that most beginners have troubles starting with it.
A correct version could look like (not tested)
#Entity
public class User extends AbstractEntity {
#Column(nullable = false)
private String firstName;
#OneToMany(cascade = ALL, fetch = FetchType.LAZY, orphanRemoval = true, mappedBy="user")
private List<Detail> details = new ArrayList<Detail>();
public void addDetail(Detail detail) {
details.add(detail);
detail.setUser(user);
}
}
#Entity
public class Detail extends AbstractEntity {
#ManyToOne
private User user;
private String hello;
public void setUser(User user){
this.user = user;
}
}
Some general advice related to creating a model mapping:
avoid bi-directional mappings whenever possible
cascade is a decision made on the service level and not at the model level and can have huge drawbacks. So for beginners avoid it.
I have no idea why people like to put JoinColumn, JoinTable and whatever join annotation on top of fields. The only reason to do this is when you have a legacy db (my opinion). When you do not like the names created by your jpa provider, provide a different naming strategy.
I would provide a custom name for the user class, because this is in some databases a reserved word.
Very simple, the first time you saved a new entity outside of hibernate session, the second time, the user object you got is a detached object, by default hibernate will not consider it is changed in this case.
*solution *
Move this logic to another service class, which annotated with #transactional
Or
Annotate your controller with transactional
Or
Override equals and hashCode method on user class may also help
I've created a simple EJB application that uses JPA for persistence and have a problem whereby optimistic locking is not functioning as I would have expected.
The application contains a class named Site which defines the model for a table named SITE in the database. The SITE table contains a column named ROW_VERSION which is referenced in the Site class using the #version annotation.
Whenever the record is updated, the ROW_VERSION is incremented by 1. So far, so good.
The problem arises when the row has changed in the time between the application reading the row using the EntityManager find method and the row being updated by the EntityManager merge method. As the ROW_VERSION for the row has been incremented by 1 and therefore is not the same as when the EntityManager find method was called, I would expect an OptimisticLockException to be thrown, but instead the changes are written to the table and in turn overwriting the changes made by the other process.
The application is running on WebSphere 8.5 and is using OpenJPA provided by the container.
Have I mis-understood how optimistic locking is supposed to work or is there something else that I need to do to make the OptimisticLockException occur?
The Site class is as follows:
#Entity
#Table(name="SITE")
public class Site {
#Id
#Column(name="SITE_ID")
private int id;
#Column(name="SITE_NAME")
private String siteName;
#Column(name="SITE_ADDRESS")
private String address;
#Column(name="ROW_VERSION")
#Version
private long rowVersion;
//getters and setters
}
The application makes uses of the Generic DAO wrapper class to invoke the EntityManager methods. The contents of the class are as follows:
public abstract class GenericDAO<T> {
private final static String UNIT_NAME = "Test4EJB";
#PersistenceContext(unitName = UNIT_NAME)
private EntityManager em;
private Class<T> entityClass;
public GenericDAO(Class<T> entityClass) {
this.entityClass = entityClass;
}
public T update(T entity) {
return em.merge(entity);
}
public T find(int entityID) {
return em.find(entityClass, entityID);
}
//other methods
}
Update - I've done some more investigation and have found this http://pic.dhe.ibm.com/infocenter/wasinfo/v8r0/index.jsp?topic=%2Fcom.ibm.websphere.nd.multiplatform.doc%2Finfo%2Fae%2Fae%2Fcejb_genversionID.html but even when I've added the #VersionColumn and #VersionStrategy annotations I still cannot get the OptimisticLockException to be thrown.