Spring rest API: saveAll - spring

I see in CrudRepository interface there is a method "saveAll".
There is anyway to use it without doing any customization to the code passing in a POST request an array of json of the corresponding entity?
I can't figure out why all the other methods are mapped except this.
Thanks Mik

It will take a collection and persist. Its hard to answer your question without sample code or what you have done so far but this is how it works on some ExampleClient code.
Just ensure you have latest version on spring-data-jpa.
#Component
public class ExampleClient {
#Autowired
private EmployeeRepository repo;
public void run() {
List<Employee> employees = createEmployees();
System.out.println(" -- saving employees --");
System.out.println(employees);
repo.saveAll(employees);
.......
........

Related

JPA - Spanning a transaction over multiple JpaRepository method calls

I'm using SpringBoot 2.x with SpringData-JPA accessing the database via a CrudRepository.
Basically, I would like to call the CrudRepository's methods to update or persist the data. In one use case, I would like to delete older entries from the database (for the brevity of this example assume: delete all entries from the table) before I insert a new element.
In case persisting the new element fails for any reason, the delete operation shall be rolled back.
However, the main problem seems to be that new transactions are opened for every method called from the CrudRepository. Even though, a transaction was opened by the method from the calling service. I couldn't get the repository methods to use the existing transaction.
Getting transaction for [org.example.jpatrans.ChairUpdaterService.updateChairs]
Getting transaction for [org.springframework.data.jpa.repository.support.SimpleJpaRepository.deleteWithinGivenTransaction]
Completing transaction for [org.springframework.data.jpa.repository.support.SimpleJpaRepository.deleteWithinGivenTransaction]
I've tried using different Propagation. (REQUIRED, SUPPORTED, MANDATORY) on different methods (service/repository) to no avail.
Changing the methods #Transactional annoation to #Transactional(propagation = Propagation.NESTED) sounded that this would just do that, but didn't help.
JpaDialect does not support savepoints - check your JPA provider's capabilities
Can I achieve the expected behaviour, not using an EntityManager directly?
I also would like to avoid to having to be using native queries as well.
Is there anything I have overlooked?
For demonstration purposes, I've created a very condensed example.
The complete example can be found at https://gitlab.com/cyc1ingsir/stackoverlow_jpa_transactions
Here are the main (even more simplified) details:
First I've got a very simple entity defined:
#Entity
#Table(name = "chair")
#Data
#AllArgsConstructor
#NoArgsConstructor
public class Chair {
// Not auto generating the id is on purpose
// for later testing with non unique keys
#Id
private int id;
#Column(name = "legs", nullable = false)
private Integer legs;
}
The connection to the database is made via the CrudRepository:
#Repository
public interface ChairRepository extends CrudRepository<Chair, Integer> {
}
This is being called from another bean (main methods here are updateChairs and doUpdate):
#Slf4j
#Service
#AllArgsConstructor
#Transactional
public class ChairUpdater {
ChairRepository repository;
/*
* Initialize the data store with some
* sample data
*/
public void initializeChairs() {
repository.deleteAll();
Chair chair4 = new Chair(1, 4);
Chair chair3 = new Chair(2, 3);
repository.save(chair4);
repository.save(chair3);
}
public void addChair(int id, Integer legCount) {
repository.save(new Chair(id, legCount));
}
/*
* Expected behaviour:
* when saving a given chair fails ->
* deleting all other is rolled back
*/
#Transactional
public void updateChairs(int id, Integer legCount) {
Chair chair = new Chair(id, legCount);
repository.deleteAll();
repository.save(chair);
}
}
The goal, I want to achieve is demonstrated by these two test cases:
#Slf4j
#RunWith(SpringRunner.class)
#DataJpaTest
#Import(ChairUpdater.class)
public class ChairUpdaterTest {
private static final int COUNT_AFTER_ROLLBACK = 3;
#Autowired
private ChairUpdater updater;
#Autowired
private ChairRepository repository;
#Before
public void setup() {
updater.initializeChairs();
}
#Test
public void positiveTest() throws UpdatingException {
updater.updateChairs(3, 10);
}
#Test
public void testRollingBack() {
// Trying to update with an invalid element
// to force rollback
try {
updater.updateChairs(3, null);
} catch (Exception e) {
LOGGER.info("Rolled back?", e);
}
// Adding a valid element after the rollback
// should succeed
updater.addChair(4, 10);
assertEquals(COUNT_AFTER_ROLLBACK, repository.findAll().spliterator().getExactSizeIfKnown());
}
}
Update:
It seems to work, if the repository is not extended from either CrudRepository or JpaRepository but from a plain Repository, definening all needed methods explicitly. For me, that seems to be a workaround rather than beeing a propper solution.
The question it boils down to seems to be: Is it possible to prevent SimpleJpaRepository from opening new transactions for every (predefined) method used from the repository interface? Or, if that is not possible, how to "force" the transaction manager to reuse the transaction, opened in the service to make a complete rollback possible?
Hi I found this documentation that looks will help you:
https://www.logicbig.com/tutorials/spring-framework/spring-data/transactions.html
Next an example take from the previous web site:
#Configuration
**#ComponentScan
#EnableTransactionManagement**
public class AppConfig {
....
}
Then we can use transactions like this:
#Service
public class MyExampleBean{
**#Transactional**
public void saveChanges() {
**repo.save(..);
repo.deleteById(..);**
.....
}
}
Yes this is possible. First alter the #Transactional annotation so that it includes rollBackFor = Exception.class.
/*
* Expected behaviour:
* when saving a given chair fails ->
* deleting all other is rolled back
*/
#Transactional(rollbackFor = Exception.class)
public void updateChairs(int id, Integer legCount) {
Chair chair = new Chair(id, legCount);
repository.deleteAll();
repository.save(chair);
}
This will cause the transaction to roll back for any exception and not just RuntimeException or Error.
Next you must add enableDefaultTransactions = false to #EnableJpaRepositories and put the annotation on one of your configuration classes if you hadn't already done so.
#Configuration
#EnableJpaRepositories(enableDefaultTransactions = false)
public class MyConfig{
}
This will cause all inherited jpa methods to stop creating a transaction by default whenever they're called. If you want custom jpa methods that you've defined yourself to also use the transaction of the calling service method, then you must make sure that you didn't annotate any of these custom methods with #Transactional. Because that would prompt them to start their own transactions as well.
Once you've done this all of the repository methods should be executed using the service method transaction only. You can test this by creating and using a custom update method that is annotated with #Modifying. For more on testing please see my answer in this SO thread. Spring opens a new transaction for each JpaRepository method that is called within an #Transactional annotated method

Return custom-typed object from JpaRepository

I have the following repository:
public interface UserRepository extends BaseDAO<User> {
Collection<User> findByEmail(#Param("email") String email);
#Query("select new com.data.CustomUser(upper(substring(u.lastName, 1, 1)) as initial, count(*)) from User u join u.chats c where c.business=:business group by upper(substring(u.lastName, 1, 1)) order by initial")
List<CustomUser> getContactsIndex(#Param("email") String email);
}
which is exposed with Spring Data REST. The User object is a managed entity, while CustomUser not and as you can see, it's build on-fly by using custom query.
Once I want to call that function, it fails with Persistent entity must not be a null! exception. Is there any way to implement this behavior?
P.S. Expose CustomUser with separate repository is impossible because it is not a managed entity.
One challenge with using Spring Data Rest is when you hit an edge case and you don't know whether you've hit a bug or whether you're just outside the scope of what the library is intended for. In this case I think you are at the edge of what SDR will easily do for you, and it's time to implement your own controller.
Spring Data Rest is looking for an Entity - in your case a User - as the return type for ALL methods in the repository to expose under /entities/search, and breaks when it doesn't find that entity type. The User it wants to serialize isn't there, hence the "Persistent entity must not be null".
The way around this is to write a simple #Controller that has a #RequestMapping for the exact same url exposed by the repository method. This will override the SDR generated implementation for that url, and from that you can return whatever you want.
Your implementation might look something like this:
#Controller
public class CustomUserController {
private final UserRepository repository;
#Inject
public CustomUserController(UserRepository repo) {
repository = repo;
}
#RequestMapping(value = "/users/search/getContactsIndex", method = GET, produces = {MediaType.APPLICATION_JSON_VALUE})
public #ResponseBody List<CustomUser> getContactsIndex(#RequestParam String email) {
return repository.getContactsIndex(email);
}
}
Be aware that there is a "recommended" way to override functionality this way. There is an open issue to document the best way to do this.

How does delete operation work with Rest in Spring Data

Currently we have exposed our methods like this
#RestController
#RequestMapping("/app/person")
public class PersonResource {
#Timed
public void delete(#PathVariable Long id) {
log.debug("REST request to delete Person: {}", id);
personRepository.delete(id);
}
}
The operations of this method, in terms of input and output, are very clear to the user developer.
This article http://spring.io/guides/gs/accessing-data-rest/ shows how to expose JPARepositories directly obviating the need of a service layer.
#RepositoryRestResource(collectionResourceRel="people", path="people")
public interface PersonRepository extends JpaRepository<PersonEntity, Long> {
}
It is not obvious to me how I can make a "delete operation" available with PathVariable Long id.
There is an excellent article on this topic. https://github.com/spring-projects/spring-data-rest/wiki/Configuring-the-REST-URL-path
But it actually shows how to supress export of a delete operation.
As documented here, Spring Data REST will expose item resources for the repository you declare. Thus, all you need to do is discover the URI of the resource to delete and issue a DELETE request to it.

Using QueryDslRepositorySupport in combination with interface repositories

since I didn't get a reply on the spring forum I'll give it a try here.
Is there a way to have a common interface repository which is extended by interfaces the following way:
#NoRepositoryBean
public interface CommonRepository<T> extends JpaRepository<T, Long>, QueryDslPredicateExecutor<T> {
T getById(final long id);
}
#Repository
public interface ConcreteRepository extends CommonRepository<ConcreteEntity> {
List<ConcreteEntity> getByNameAndAddress(final String name, final String address);
}
public class ConcreteRepositoryImpl extends QueryDslRepositorySupport implements ConcreteRepository {
private BooleanExpression nameEquals(final QConcreteEntity entity, final String name) {
return entity.eq(name);
}
public List<ConcreteEntity> getByNameAndAddress(final String name, final String address) {
QConcreteEntity entity = QConcreteEntity.concreteEntity;
return from(entity).where(entity.name.eq(name).and(entity.address.eq(address))).list(entity);
}
}
The problem with the implementation is that I have to implement getById(final long id)
in each concrete class. I don't want to do that. Normally, spring data automatically knows about each entity. Also I want to have the functionality of QueryDslRepositorySupport.
In my example it normally generates something like:
select .. from concreteentity en where en.id = ...
Is there a way to solve it? I already stumbled upon
Spring Jpa adding custom functionality to all repositories and at the same time other custom funcs to a single repository
and
http://docs.spring.io/spring-data/data-jpa/docs/current/reference/html/repositories.html#repositories.custom-implementations
but I don't think these solutions are helpful and I don't entirely understand how I can use them to solve the problem.
Thanks,
Christian
One way to create a generic getById under QuerydslRepositorySupport is like this
T getById(long id) {
return getEntityManager().find(getBuilder().getType(), id)
}

spring mvc 3 caching example

I have requirement for spring mvc 3 caching. Requirement is : while starting the server, we need to call database for one dropdown and put those values in the cache. So that whenever we required those values, we need to retrieve from cache.
Please help me with an example.
Thanks in advance.
May be you can use init-method (Spring 2.5) or #PostConstruct annotation (in Spring 3.0).
This method will be called during server start up
The following is code snippet
#Component
public class CacheDBData {
private String values[];
//add setter & getter
//This will be called during server start up after properties are initialised
#PostConstruct
public void getDataFromDB() {
values = //Logic to get data from DB and store that in values property
}
}
Suppose for example you can use in class as follows
#controller
public class HomeController {
#Autowired
private CacheDBData cacheDBData ;
//getter and setters
private void methodxyz() {
String values[] = cacheDBData.getValues();
}
}
I've had success with Ehcahe for Spring. There's a couple of config files to setup but after that you simply annotate the methods you want to cache the output from and it just works.
This has the advantage that you can change the values coming back from the service/database and NOT have to restart your app, unlike the accepted answer.

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