Java JPA EntityManager has methods for creating a Query and a TypedQuery for jpql and named queries:
public Query createQuery(String qlString);
public <T> TypedQuery<T> createQuery(String qlString, Class<T> resultClass);
public Query createNamedQuery(String name);
public <T> TypedQuery<T> createNamedQuery(String name, Class<T> resultClass);
So, for a native query, why does it accept a raw Class parameter, and return a Query, rather than a TypedQuery?
public Query createNativeQuery(String sqlString);
public Query createNativeQuery(String sqlString, Class resultClass);
That is, why isn't the second form of createNativeQuery method:
public <T> TypedQuery<T> createNativeQuery(String sqlString, Class<T> resultClass);
following the pattern of the other two.
I have this code in Foo.scala
object Foo extends App
{
def bar() = () => println("hello")
bar()()
}
If I run
scalac Foo.scala
I obtain three .class files:
Foo$.class
Foo$delayedInit$body.class
Foo.class
If then I run
javap 'Foo$.class'
I get on stdout
Compiled from "Foo.scala"
public final class Foo$ implements scala.App {
public static Foo$ MODULE$;
public static {};
public java.lang.String[] args();
public void delayedInit(scala.Function0<scala.runtime.BoxedUnit>);
public void main(java.lang.String[]);
public long executionStart();
public java.lang.String[] scala$App$$_args();
public void scala$App$$_args_$eq(java.lang.String[]);
public scala.collection.mutable.ListBuffer<scala.Function0<scala.runtime.BoxedUnit>> scala$App$$initCode();
public void scala$App$_setter_$executionStart_$eq(long);
public final void scala$App$_setter_$scala$App$$initCode_$eq(scala.collection.mutable.ListBuffer<scala.Function0<scala.runtime.BoxedUnit>>);
public scala.Function0<scala.runtime.BoxedUnit> bar();
public static final void $anonfun$bar$1();
public final void delayedEndpoint$Foo$1();
}
As you can see the lambda that is returned from the bar method is
compiled into public static final void $anonfun$bar$1();
I would like to be able to have all the lambda used in my scala code compiled as private method instead of public ones (it shouldn't be a problem when those functions are just local method variables, since they can only be accessed from within the method in which they are declared). Is there a way to achieve that?
P.S.
I'm asking because I'm using Scala to create Java EE's EJB classes and EJB classes used with no-interface view cannot have methods that are both public and final (it must be possible to instantiate a subclass that overrides all the public methods to create a proxy)
Is there any way to reference an attribute of a parameter that is part of a query for a JPA repository?
My sample is
#Entity
public class Matchday implements Serializable {
#Id
private int matchdayNumber;
//..
//setters and getters defined
//..
//hashCode and equals methods overridden
}
public interface MyRepository extends JpaRepository<Matchday, Integer> {
#Query("... WHERE t.matchday.matchdayNumber < :matchday.matchdayNumber - 1;")
public findByCriteria(Matchday matchday);
}
The construction :matchday.matchdayNumber does not seem to be a valid syntax. Is there any other way to do it than passing the int value for matchdayNumber instead of a reference to Matchday object to this method?
Looks like this is possible with Spring JPA Data which allows SpEL in queries.
public interface MyRepository extends JpaRepository<Matchday, Integer> {
#Query("... WHERE t.matchday.matchdayNumber < :#{#matchday.matchdayNumber - 1}")
public findByCriteria(Matchday matchday);
}
I am using Spring Data MongodB 1.4.2.Release version. For Spring Data MongoDB, I have created the custom repository interface and implementation in one location and create custom query function getUsersName(Users users).
However I am still getting below exception:
Caused by: org.springframework.data.mapping.PropertyReferenceException:
No property get found for type Users! at org.springframework.data.mapping.PropertyPath. (PropertyPath.java:75) at
org.springframework.data.mapping.PropertyPath.create(PropertyPath.java:327) at
org.springframework.data.mapping.PropertyPath.create(PropertyPath.java:359) at
org.springframework.data.mapping.PropertyPath.create(PropertyPath.java:359) at
org.springframework.data.mapping.PropertyPath.create(PropertyPath.java:307) at
org.springframework.data.mapping.PropertyPath.from(PropertyPath.java:270) at
org.springframework.data.mapping.PropertyPath.from(PropertyPath.java:241) at
org.springframework.data.repository.query.parser.Part.(Part.java:76) at
org.springframework.data.repository.query.parser.PartTree$OrPart.(PartTree.java:201) at
org.springframework.data.repository.query.parser.PartTree$Predicate.buildTree(PartTree.java:291) at
org.springframework.data.repository.query.parser.PartTree$Predicate.(PartTree.java:271) at
org.springframework.data.repository.query.parser.PartTree.(PartTree.java:80) at
org.springframework.data.mongodb.repository.query.PartTreeMongoQuery.(PartTreeMongoQuery.java:47)
Below is my Spring Data MongoDB structure:
/* Users Domain Object */
#Document(collection = "users")
public class Users {
#Id
private ObjectId id;
#Field ("last_name")
private String last_name;
#Field ("first_name")
private String first_name;
public String getLast_name() {
return last_name;
}
public void setLast_name(String last_name) {
this.last_name = last_name;
}
public String getFirst_name() {
return first_name;
}
public void setFirst_name(String first_name) {
this.first_name = first_name;
}
}
/* UsersRepository.java main interface */
#Repository
public interface UsersRepository extends MongoRepository<Users,String>, UsersRepositoryCustom {
List findUsersById(String id);
}
/* UsersRepositoryCustom.java custom interface */
#Repository
public interface UsersRepositoryCustom {
List<Users> getUsersName(Users users);
}
/* UsersRepositoryImpl.java custom interface implementation */
#Component
public class UsersRepositoryImpl implements UsersRepositoryCustom {
#Autowired
MongoOperations mongoOperations;
#Override
public List<Users> getUsersName(Users users) {
return mongoOperations.find(
Query.query(Criteria.where("first_name").is(users.getFirst_name()).and("last_name").is(users.getLast_name())), Users.class);
}
/* Mongo Test function inside Spring JUnit Test class calling custom function with main UsersRepository interface */
#Autowired
private UsersRepository usersRepository;
#Test
public void getUsersName() {
Users users = new Users();
users.setFirst_name("James");`enter code here`
users.setLast_name("Oliver");
List<Users> usersDetails = usersRepository.getUsersName(users);
System.out.println("users List" + usersDetails.size());
Assert.assertTrue(usersDetails.size() > 0);
}
The query method declaration in your repository interface is invalid. As clearly stated in the reference documentation, query methods need to start with get…By, read_By, find…By or query…by.
With custom repositories, there shouldn't be a need for method naming conventions as Oliver stated. I have mine working with a method named updateMessageCount
Having said that, I can't see the problem with the code provided here.
I resolved this issue with the help of this post here, where I wasn't naming my Impl class correctly :
No property found for type error when try to create custom repository with Spring Data JPA
I am using spring-data for mongodb with querydsl.
I have a repository
public interface DocumentRepository extends MongoRepository<Document, String> ,QueryDslPredicateExecutor<Document> {}
and an entity
#QueryEntity
public class Document {
private String id;
private String name;
private String description;
private boolean locked;
private String message;
}
I need to load a list of documents with id and name informations.
So only id and name should be loaded and set in my entity.
I think query projection is the right word for it.
Is this supported?
In addition I need to implement some lazy loading logic.
Is there anything like "skip" and "limit" features in a repository?
There's quite a few aspects to this, as it is - unfortunately - not a single question but multiple ones.
For the projection you can simply use the fields attribute of the #Query annotation:
interface DocumentRepository extends MongoRepository<Document, String>, QuerydslPredicateExecutor<Document> {
#Query(value = "{}", fields = "{ 'id' : 1, 'name' : 1 }")
List<Document> findDocumentsProjected();
}
You can combine this with the query derivation mechanism (by not setting query), with pagination (see below) and even a dedicated projection type in the return clause (e.g. a DocumentExcerpt with only id and name fields).
Pagination is fully supported on the repository abstraction. You already get findAll(Pageable) and a Querydsl specific version of the method by extending the base interfaces. You can also use the pagination API in finder methods adding a Pageable as parameter and returning a Page
Page<Document> findByDescriptionLike(String description, Pageable pageable)
See more on that in the reference documentation.
Projection
For all I know projections are not supported by the default Spring Data repositories. If you want to make sure only the projection is sent from the DB to your application (e.g. for performance reasons) you will have to implement the corresponding query yourself. Adding custom methods to extensions of the standard repo should not be too much effort.
If you just want to hide the content of certain fields from some client calling your application, you would typically use another set of entity objects with a suitable mapping in between. Using the same POJO for different levels of detail is always confusing as you will not know if a field is actually null or if the value was just suppressed in a certain context.
Pagination
I am currently not able to test any code, but according to the documentation of QueryDslPredicateExecutor the method findAll(predicate, pageable) should be what you want:
it returns a Page object that is a regular Iterable for your Document
you have to pass it a Pageable for which you can e.g. use a PageRequest; initializing it for known values of skip and limit should be trivial
I also found this approach for JPA
Spring Data JPA and Querydsl to fetch subset of columns using bean/constructor projection
I am currently trying to implement this for MongoDB.
According to the Answer of this -> Question <- I implemeted following solution.
Entity
#QueryEntity
public class Document extends AbstractObject {
}
Custom QuerydslMongoRepository
public interface CustomQuerydslMongoRepository<T extends AbstractObject,ID extends Serializable> extends MongoRepository<T, ID> ,QueryDslPredicateExecutor<T>{
Page<T> findAll(Predicate predicate, Pageable pageable,Path... paths);
Page<T> findAll(Predicate predicate, Pageable pageable,List<Path> projections);
}
Custom QuerydslMongoRepository Implementation
public class CustomQuerydslMongoRepositoryImpl<T extends AbstractObject,ID extends Serializable> extends QueryDslMongoRepository<T,ID> implements CustomQuerydslMongoRepository<T,ID> {
//All instance variables are available in super, but they are private
private static final EntityPathResolver DEFAULT_ENTITY_PATH_RESOLVER = SimpleEntityPathResolver.INSTANCE;
private final EntityPath<T> path;
private final PathBuilder<T> pathBuilder;
private final MongoOperations mongoOperations;
public CustomQuerydslMongoRepositoryImpl(MongoEntityInformation<T, ID> entityInformation, MongoOperations mongoOperations) {
this(entityInformation, mongoOperations,DEFAULT_ENTITY_PATH_RESOLVER);
}
public CustomQuerydslMongoRepositoryImpl(MongoEntityInformation<T, ID> entityInformation, MongoOperations mongoOperations, EntityPathResolver resolver) {
super(entityInformation, mongoOperations, resolver);
this.path=resolver.createPath(entityInformation.getJavaType());
this.pathBuilder = new PathBuilder<T>(path.getType(), path.getMetadata());
this.mongoOperations=mongoOperations;
}
#Override
public Page<T> findAll( Predicate predicate, Pageable pageable,Path... paths) {
Class<T> domainType = getEntityInformation().getJavaType();
MongodbQuery<T> query = new SpringDataMongodbQuery<T>(mongoOperations, domainType);
long total = query.count();
List<T> content = total > pageable.getOffset() ? query.where(predicate).list(paths) : Collections.<T>emptyList();
return new PageImpl<T>(content, pageable, total);
}
#Override
public Page<T> findAll(Predicate predicate, Pageable pageable, List<Path> projections) {
Class<T> domainType = getEntityInformation().getJavaType();
MongodbQuery<T> query = new SpringDataMongodbQuery<T>(mongoOperations, domainType);
long total = query.count();
List<T> content = total > pageable.getOffset() ? query.where(predicate).list(projections.toArray(new Path[0])) : Collections.<T>emptyList();
return new PageImpl<T>(content, pageable, total);
}
}
Custom Repository Factory
public class CustomQueryDslMongodbRepositoryFactoryBean<R extends QueryDslMongoRepository<T, I>, T, I extends Serializable> extends MongoRepositoryFactoryBean<R, T, I> {
#Override
protected RepositoryFactorySupport getFactoryInstance(MongoOperations operations) {
return new CustomQueryDslMongodbRepositoryFactory<T,I>(operations);
}
public static class CustomQueryDslMongodbRepositoryFactory<T, I extends Serializable> extends MongoRepositoryFactory {
private MongoOperations operations;
public CustomQueryDslMongodbRepositoryFactory(MongoOperations mongoOperations) {
super(mongoOperations);
this.operations = mongoOperations;
}
#SuppressWarnings({ "rawtypes", "unchecked" })
protected Object getTargetRepository(RepositoryMetadata metadata) {
return new CustomQuerydslMongoRepositoryImpl(getEntityInformation(metadata.getDomainType()), operations);
}
protected Class<?> getRepositoryBaseClass(RepositoryMetadata metadata) {
return CustomQuerydslMongoRepository.class;
}
}
}
Entity Repository
public interface DocumentRepository extends CustomQuerydslMongoRepository<Document, String>{
}
Usage in Service
#Autowired
DocumentRepository repository;
public List<Document> getAllDocumentsForListing(){
return repository.findAll( QDocument.document.id.isNotEmpty().and(QDocument.document.version.isNotNull()), new PageRequest(0, 10),QDocument.document.name,QDocument.document.version).getContent();
}