If I have a list of natural Ids, how can I fetch all the records in the DB associated with these natural Ids at once?
All I've seen are methods that let you find an entity by a natural Id, an example of one is shown below.
#Override
public Optional<T> findBySimpleNaturalId(ID naturalId) {
Optional<T> entity = entityManager.unwrap(Session.class)
.bySimpleNaturalId(this.getDomainClass())
.loadOptional(naturalId);
return entity;
}
I am looking for a method that can take a list natural Ids and fetch all the entities with these natural Ids. My current Entity has a autogenerated UUID and a naturalId and I'd like to keep it this way.
Is there something like this below
List<Song> songs = entityManager
.unwrap(Session.class)
.byMultipleSimpleNaturalIds(Song.class)
.multiLoad(songGroup.getSongIds());
// or using the repository
customRepository.findAllByNaturalId(...)
The examples you've seen are showing you how to build them yourself, as spring does not provide individual methods for you; it knows nothing about properties in your entity other than it must have an id. If you want a findAllByNaturalId method, you have to define it in the interface.
Specifying this in your customRepository:
public List<Song> findByNaturalIdIn(List<Int> naturalIds);
Spring should generate an implementation that creates a query similar to "Select s from Song s where s.naturalId In :naturalIds".
If it doesn't, just add that JPQL query string as an annotation and it will execute it for you:
#Query(value = "Select s from Song s where s.naturalId In :naturalIds")
public List<Song> findByNaturalIdIn(List<Int> naturalIds);
Or you can write your own implementation method to execute your loadOptional calls, or any query you wish, but you still must define the method in your repository.
Related
I have a list of entities on which I want to perform an update, I know I could update the table with list of String/Integer.. etc as the parameter with something like
#Query("update tableName i set i.isUpdated = true where i.id in :ids")
void markAsUpdated(#Param("ids") List<Integer> itemIds);
I'm trying to avoid repeated conversion of list of entities to list of Ids for making the query in DB. I know there are deleteAll and deleteInBatch commands which accept parameter as list of entities.
How do I do this in JPA Query, I tried the following but it didn't work yet.
#Modifying(flushAutomatically = true, clearAutomatically = true)
#Query("update tableName i set i.updated = true where i in :items")
void markAsUpdated(#Param("items") List<Item> items)
The query needs ids, it doesn't know how to deal with entities.
You have multiple options:
Just pass ids to the method, the client is responsible for extracting ids.
Pass entities and use SpEL for extracting ids
As suggested in the comments use a default method to offer both APIs and to delegate from one to the other.
As for the question that came up in the comments: You can move the method for extracting the id into a single method by either have relevant entities implement an interface similar to this one:
interface WithId {
Long getId();
}
Or by passing a lambda to the method, doing the conversion for a single entity:
List<ID> extractIds(List<E> entities, Function<E, ID> extractor) {
// ...
}
I have two entities in a bi-directional many to many relationship.
A <-> many to many <-> B
I have an endpoint where a client can create an instance of A, and at the same time add some number of B entities to that A, by passing in an array of B entity id keys. Please keep in mind that these B entities already exist in the database. There is no business or software design case for tightly coupling their creation to the creation of A.
So class A looks like this, and B is the same, but with references to A.
#Entity
class A {
#Id
#GeneratedValue
int id;
#ManyToMany
List<B> bs;
String someValue;
int someValue2;
// With some getters and setters omitted for brevity
}
So at first try my endpoint code looks like this.
public A createA(#RequestBody A aToCreate) {
A savedA = aRepository.save(aToCreate);
savedA.getbs().forEach(b -> Service.callWithBValue(b.getImportantValue());
}
And the client would submit a JSON request like this to create a new A which would contain links to B with id 3, and B with id 4.
{
"bs": [{id:3}, {id:10}],
"someValue": "not important",
"someValue2": 1
}
Okay so everything's working fine, I see all the fields deserializing okay, and then I go to save my new A instance using.
aRepository.save(aToCreate);
And that works great... except for the fact that I need all the data associated with the b entity instances, but the A object returned by aRepository.save() has only populated the autofill fields on A, and done nothing with the B entities. They're still just hollow entities who only have their ids set.
Wut.
So I go looking around, and apparently SimpleJpaRepository does this.
#Transactional
public <S extends T> S save(S entity) {
if (entityInformation.isNew(entity)) {
em.persist(entity);
return entity;
} else {
return em.merge(entity);
}
}
And since the A entity is brand new, it only persists the A entity, but it doesn't merge it so I don't get any of the rich B data. So okay, if I modify my code to take this into account I get this.
public A createA(#RequestBody A aToCreate) {
A savedA = aRepository.save(aRepository.save(aToCreate));
savedA.getbs().forEach(b -> Service.callWithBValue(b.getImportantValue());
}
Which works just fine. The second pass through the repository service it merges instead of persists, so the B relationships get hydrated.
My question is: Is this correct, or is there something else I can do that doesn't look so ineloquent and awful?
To be clear this ONLY matters when creating a brand new instance of A, and once A is in the database, this isn't an issue anymore because the SimpleJpaRepository will flow into the em.merge() line of code. Also I have tried different CascadingType annotations on the relationship but none of them are what I want. Cascading is about persisting the state of the parent entity's view of its children, to its children, but what I want to do is hydrate the child entities on new instance creation, instead of having to make two trips to the database.
In the case of a new A, aToCreate and savedA are the same instance because that is what the JPA spec madates:
https://docs.oracle.com/javaee/6/api/javax/persistence/EntityManager.html#persist(java.lang.Object)
Make an instance managed and persistent.
Spring Data simply returns the same instance so persist/merge can be abstracted into one method.
If the B instances you wish to associate with A are existing entities then you need to fetch a reference to these existing instances and set them on A. You can do this without a database hit by using the T getOne(ID id) method of Spring Data's JpaRepository:
https://docs.spring.io/spring-data/jpa/docs/2.1.4.RELEASE/api/
You can do this in your controller or possibly via a custom deserializer.
This is what I ended up going with. This gives the caller the ability to save and hydrate the instance in one call, and explains what the heck is going on. All my Repository instances now extend this base instance.
public interface BaseRepository<T, ID> extends JpaRepository<T, ID> {
/**
* Saves an instance twice so that it's forced to persist AND then merge. This should only be used for new detached entities that need to be saved, and who also have related entities they want data about hydrated into their object.
*/
#Transactional
default T saveAndHydrate(T save) {
return this.save(this.save(save));
}
}
I'm trying to return (or fetch) all the records from the database based on an ID provided by me. I'm using JPA and i'm aware of findAll() method but it returns all the records without any criteria, I created a custom query and it is only returning a unique value from the table but i want to return all records based on a criteria.
For example, findAllByUserID(String UserID) method should return all the records based on that UserID not just one.
I'd appreciate any help or suggestion.
Thanks
Have a look at the doc. There you will find the keywords you can use to declare methods in repository interfaces that will generate the according queries:
https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#jpa.query-methods
In your case: If userID is an attribute of your entity you can add a method
List<YourEntity> findByfindAllByUserID(String userId)
to your repository interface.
First, make sure that you're not using any aggregate function in your select query such as DISTINCT()
Then make sure that the the method which is implementing that query is returning a List of you're desired result.
here's how it should look :
#Query("select t from table t where t.code = ?1")
List<Result> findAllByUserID(String UserID);
I have two entities: User and Connection, along with two appropriate repositories. Both entities has #GraphId id field. Connection entity has User user field.
In ConnectionRepository interface I added following method:
List<Connection> findByUserId(long userId)
But it doesn't work. It generates incorrect cypher query. I think it incorrect, because it contains clause like this:
WHERE user.id = 15
which is not working, because id is not a property. It must be:
WHERE id(user) = 15
Is this a bug? In any case, how can I get it to work?
The derived query translates to the property id of the user defined on the Connection. It is quite possible that node entities contain a user managed id property as well and it would be incorrect to assume that id is always the node id.
In this case, you might want to use a #Query instead.
#Query("MATCH (user:label) WHERE ID(user)={0} return user")
List<Connection> findByUserId(long userId)
I want to test if created entity has been correctly persisted to database.There is a service integration test for create method:
#SpringApplicationContext({"setting ...."})
public class PersonServiceIntegrationTest extends UnitilsJUnit4 {
#SpringBeanByName
private PersonService personService;
#Test
public void createPerson() {
String name = "Name";
String sname = "Surename";
DtoPerson item = personService.createPerson(name, sname, Arrays.asList( new DtoAddress("Pisek","CZE", true), new DtoAddress("Strakonice", "CZE", false) );
Assert.notNull("Cannot be null", item);
/*
* This assertion fails because of transaction (I suppose) - item is not in
* database right now.
* Why? Returned dto 'item; is not null?
*/
//domain with all fetched related entities, eg. address
Person p = personService.getPerson(item.getIdPerson());
List<Address> addresses = p.getAddresses();
Assert.notNull("Cannot be null", p);
Assert.notNull("Cannot be null", addresses);//return collection of Address
Assert.notFalse("Cannot be emtpty", addresses.isEmpty());
ReflectionAssert.assertPropertyLeniens("City", Arrays.asList("Pisek", "Strakonice"), addresses);
}
}
Is it necessary to test create entity if I use hibernate? Someone can write you try to test low-level hibernate but hibernate has own tests. There is a trivial code above but I can imagine some specific code which persists more entites at same time (eg. one-many plus several one-one relations). And I want to test if relations has been correctly persisted.
Is there a pattern to do test this way? I have a problem, that record is not at database. I don't want to use returned dto (it presents only agregate root entity - person, but it does not say about person basic data (one-many), person address (one-many) etc.)... i want to get persisted record.
What I do to test the persistence is:
1) I create the Domain entity,
2) save it with Hibernate/JPA,
3) flush and clear the hibernate session/entity manager
4) load the entity again with hibernate
5) compare the original entity with the one that I have (re)loaded
so I am pretty sure that the mapping is more or less correct and every thing get persisted
I decided to rework service method for create person.
PersonService is responsible only to create domain entity Person - test will do only test the returned DtoPerson and its values.
PersonService will inject AddressService, PersonBasicDataService, which they have own create methods with collection as parameter. These services will have own test classes and test only returned collection of DtoAddress or DtoPersonBasicData.
Tests will be simply and will solve only own responsibility. :-)
As #Ralph said in comments under his answer - this test case is not about service layer. There is necessary to test domain layer. And what there is a new idea which I do not use in integration tests - tests has own hibernate session.