Perform a search on DisabScreenRequest and fetch its child details also. Using DTO projections using a Constructor Expression and JPQL.
The parent entity with a child table.
#Entity
#Table(name = "SCREEN_REQUEST")
public class DisabScreenRequest implements Serializable {
private static final long serialVersionUID = 1L;
#Id
private long requestId;
#Column(name = "CIVILID")
private Long civilId;
#ManyToMany()
#JoinTable(name = "_DISAB_SCREEN_REQ_DETAILS", joinColumns = {
#JoinColumn(name = "REQUEST_ID") }, inverseJoinColumns = { #JoinColumn(name = "DISABILTY_TYPE_ID") })
private Set<DisabMaster> disabilities = new HashSet<DisabMaster>();
public DisabScreenRequest() {
}
}
This is the disability table.
#Entity
#Table(name="DISAB_MASTER")
#Immutable
public class DisabMaster implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#Column(name="DIS_TYPE_ID")
private long disabilityTypeId;
#Column(name="DIS_TYPE_DESC")
private String disTypeDesc;
public DisabMaster() {
super();
}
}
Had to fetch all the requests along with the disability for each request.
Search DTO(using this I had other joins to add other than one mentioned here).
public class RequestSearchDto {
private long requestId;
private Long civilId;
private Set<DisabMaster> disabilities;
public RequestSearchDto() {
super();
}
public RequestSearchDto(long requestId, Long civilId) {
super();
this.requestId = requestId;
this.civilId = civilId;
}
public RequestSearchDto(long requestId, Long civilId, Set<DisabMaster> disabilities) {
super();
this.requestId = requestId;
this.civilId = civilId;
this.disabilities = disabilities;
}
}
This is my JPQL query
public interface ReposJPQL {
public String GET__REQUEST = "SELECT DISTINCT new org.test.RequestSearchDto "
+ "(dsr.requestId, dsr.civilId, dsr.disabilities)"
+ " FROM DisabScreenRequest dsr WHERE 1=1 ";
}
This will get an
org.hibernate.exception.SQLGrammarException: could not extract ResultSet.
What Iam I doing wrong here, how can I fetch the child table data ?
Let me know if you need any info
Stack trace :
Caused by: java.sql.SQLException: ORA-00936: missing expression
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:113)
at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:331)
at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:288)
at oracle.jdbc.driver.T4C8Oall.receive(T4C8Oall.java:754)
at oracle.jdbc.driver.T4CPreparedStatement.doOall8(T4CPreparedStatement.java:219)
at oracle.jdbc.driver.T4CPreparedStatement.executeForDescribe(T4CPreparedStatement.java:813)
at oracle.jdbc.driver.OracleStatement.executeMaybeDescribe(OracleStatement.java:1051)
at oracle.jdbc.driver.T4CPreparedStatement.executeMaybeDescribe(T4CPreparedStatement.java:854)
at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1156)
at oracle.jdbc.driver.OraclePreparedStatement.executeInternal(OraclePreparedStatement.java:3415)
at oracle.jdbc.driver.OraclePreparedStatement.executeQuery(OraclePreparedStatement.java:3460)
at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeQuery(NewProxyPreparedStatement.java:76)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:60)
If you need to fetch parent entity with a collection of its nested child entities you can use this simple approach using #EntityGraph annotation or JPQL with join fetch:
#Entity
public class Parent {
//...
#OneToMany
private List<Child> children;
}
#Entity
public class Child {
//...
}
interface ParentRepo extends JpaRepository<Parent, Integer> {
// with #EntityGraph
#EntityGraph(attributePaths = "children")
#Override
List<Parent> findAll();
// or manually
#Query("select distinct p from Parent p left join fetch p.children")
List<Parent> findWithQuery();
}
Note to use distinct in your query to avoid duplicate records.
Example: duplicate-parent-entities
More info: DATAJPA-1299
AFAIK, you can't use constructor expression which take a Collection.
See the JPA 2.2 Spec, section 4.14 BNF, read about the constructor expression:
constructor_expression ::=
NEW constructor_name ( constructor_item {, constructor_item}* )
constructor_item ::=
single_valued_path_expression |
scalar_expression |
aggregate_expression |
identification_variable
This is a perfect use case for Blaze-Persistence Entity Views.
I created the library to allow easy mapping between JPA models and custom interface defined models, something like Spring Data Projections on steroids. The idea is that you define your target structure the way you like and map attributes(getters) via JPQL expressions to the entity model. Since the attribute name is used as default mapping, you mostly don't need explicit mappings as 80% of the use cases is to have DTOs that are a subset of the entity model.
A mapping for your model could look as simple as the following
#EntityView(DisabScreenRequest.class)
interface RequestSearchDto extends Serializable {
#IdMapping
long getRequestId();
Long getCivilId();
Set<DisabMaster> getDisabilities();
}
Querying is a matter of applying the entity view to a query, the simplest being just a query by id.
RequestSearchDtodto = entityViewManager.find(entityManager, RequestSearchDto.class, id);
But the Spring Data integration allows you to use it almost like Spring Data Projections: https://persistence.blazebit.com/documentation/1.4/entity-view/manual/en_US/#spring-data-features
Related
I have a Springboot Application with Repositories having Spring Data JPA Queries like findOne, findAll and also derived ones like findByID or findByName etc.
What I want to achieve is multitenancy. All entities have an "account_id" column which holds the tenant.
How do I add a filter like "account_id" to all the queries metioned above without using derived queries that contains those name slike findIdAndAccountid (which would be findone)
#Repository
public interface CategoryRepository extends JpaRepository<Category, Long> {
Category findByName(String name);
}
Here's the corresponding entity
#Entity
#Table(name = "unit")
#Data
public class Unit {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private Long id;
private String name;
#Column(name = "account_id")
private Long account_id;
}
I know most people use schemas as tenant separation but that's impossible for me. Is there a way (I didn't find one) to add such a tenant filter condition on those queries without writing NamedQueries or using DerivedQueries. An elegeant solution like annotate the repository or entity or maybe the queries that all queries should add the additional filter "account_id"?
You can add Where clause on your Entity classes (Didnt had time to test )
#Entity
#Table(name = "unit")
#Data
#Where(clause = "account_id= :account_id")
public class Unit {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private Long id;
private String name;
#Column(name = "account_id")
private Long account_id;
}
Update and Solution
1. Create a Filter & FilterDef on the entity like so
#FilterDef(name="accountFilter", parameters=#ParamDef( name="accountId", type="long" ) )
#Filters( {
#Filter(name="accountFilter", condition=":accountId = account_id")
} )
public class Category {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private Long id;
private String name;
#Column(name = "account_id")
private Long account_id;
}
enable filtering in the controller by autowiring entitymanager, writing a method to enable the filter and activate the filter in #ModelAttribute for each request
#RestController
#RequestMapping(path = "/categories",produces = MediaType.APPLICATION_JSON_VALUE )
public class CategoryController {
private final CategoryRepository repository;
#Autowired
private EntityManager entityManager;
CategoryController(CategoryRepository repository) {
this.repository = repository;
}
private void activateFilter() {
Session session = entityManager.unwrap(Session.class);
Filter filter = session.enableFilter("accountFilter");
filter.setParameter("accountId", Long.valueOf(TenantContext.getCurrentTenant()));
}
#ModelAttribute
public void initFilter() {
activateFilter();
}
... your rest methods here
}
Suppose I have 2 entities, Parent and Child, where the parent contains 1..n children:
#Entity
#Data #NoArgsConstructor
public class Parent {
#Id #GeneratedValue
private long id;
private String basic;
private String detail;
#OneToMany(fetch = FetchType.EAGER)
private Set<Child> children = new HashSet<>();
public Parent(String basic, String detail, Set<Child> children) {...}
}
#Entity
#Data #NoArgsConstructor
public class Child {
#Id
#GeneratedValue(strategy = GenerationType.TABLE)
private long id;
private String basic;
private String detail;
public Child(String basic, String detail) {...}
}
I can load Parent-entities by using a JpaRepository:
public interface ParentRepository extends JpaRepository<Parent, Long> { }
// in Controller or Service
List<Parent> parents = parentRepository.findAll();
I'm trying to use projections. For this reason I want to know if it is possible to manually load the parents with a Query, so that i could only load needed data. In a perfect world this could look something like this:
// Dtos, the String detail is not required for both Parent and Child
#Value
public class ParentDto {
long id;
String basic;
Collection<Child> children;
public ParentDto(long id, String basic, Collection<ChildDto> children) {...}
}
#Value
public class ChildDto {
long id;
String basic;
public ChildDto(long id, String basic) {...}
}
and
public interface ParentRepository extends JpaRepository<Parent, Long> {
// Projection - *NOT WORKING*, this is what i would like
#Query("select p.id, p.basic, p.children.id, p.children.basic from Parent p")
List<ParentDto> findAllProjected();
}
This obviously fails, because it will join the all parents with their child, resulting in amount_of_parents * amount_of_their_children rows. The ParentDto would need a contrustor public ParentDto(long id, String basic, ChildDto child) {...}, so i had n ParentDtos per parent where n is the number of children the parent has.
Do i have to manually group the rows by the parents Id's and collect the ChildDtos together? Can I solve this using a subselect? I know Jpa solves this by selecting the parents and doing 1 select for each parent, fetching their children (when i use the autogenerated repository method). I was really hoping that projections/views would be much easier as they are such a fundamental requirement for me and most likely many other applications. Having to always load all data, load only the wanted data - but without their associations or having to load the associations manually for each entity seems like a bumper.
Note: i did try InterfaceProjection but do not want to use it due to it loading all data and stripping away unnessecary parts only when serializing it to json.
Thanks in regards!
In spring data JPA we can write query methods to execute query. I have two entities
class A {
#Id
#Column
private String id;
private String name;
#ManyToOne
#JoinColumn(name = "b_field")
private B b;
}
class B {
#Id
#KeyField
#Column
private String id;
private String b_field
}
I want to write a query method "findByNameOrderByb_field" i.e find all the rows having name as provided and order the results on the basis of class B's field i.e b_field. Writing above function is not returning ordered results. Is there any way I can write this orderby query method in spring boot.
public interface ARepository extends CrudRepository<A, String> {
List<A> findByNameOrderByb_field(String name);
}
the above function is not returning ordered results based on B's b_field.
To access properties of B you have to include the field name of B in the declaration of the query method.
public interface ARepository extends CrudRepository<A, String> {
List<A> findByNameOrderByb_b_field(String name);
}
More information how SpringData resolves nested Properties can be found under:
Query Property Expressions
I have build my data model using JPA and am using Hibernate's EntityManager to access the data. I am using this configuration for other classes and have had no problems.
The issue is that I created an entity with a composite primary key (the two keys are foreign keys) , adding elements works perfectly I checked it in database but I am not able to retrieve the populated row from database.
For example if I query "FROM Referentiel" to return a list of all referentiels in the table, I get this [{},{}] my list.size() has the proper number of elements (2), but the elements are null.
The entity:
#Entity
#Table(name = "Et_referentiel")
public class Referentiel implements Serializable {
/**
*
*/
private static final long serialVersionUID = 1L;
#Id
#ManyToOne
#JoinColumn(name = "id_projet")
private Projet projet;
#Id
#ManyToOne
#JoinColumn(name = "id_ressource")
private Ressource ressource;
#Column(name = "unite", nullable = false)
private String unite;
}
here is my controller getList method:
#PostMapping(value = "/list", consumes = { MediaType.APPLICATION_JSON_UTF8_VALUE })
public List<Referentiel> listReferentiel(#RequestBody Long idProjet) {
List<Referentiel> referentiel = referentielService.listReferentiel(idProjet);
return referentiel;
}
and here is my dao methods:
#Autowired
private EntityManager em;
#Override
public void ajouterReferentiel(Referentiel ref) {
em.persist(ref);
em.flush();
}
#SuppressWarnings("unchecked")
#Override
public List<Referentiel> listReferentiel(Long idProjet) {
Query query = em.createQuery("Select r from Referentiel r where r.projet.idProjet=:arg1");
query.setParameter("arg1", idProjet);
em.flush();
List<Referentiel> resultList = query.getResultList();
return resultList;
}
Any help is greatly appreciated.
Try creating a class representing your composite key:
public class ReferentielId implements Serializable {
private static final long serialVersionUID = 0L;
private Long projet; // Same type than idProjet, same name than inside Referentiel
private Long ressource; // Same type than idRessource (I guess), same name than inside Referentiel
// Constructors, getters, setters...
}
And assign it to your entity having that composite key.
#Entity
#IdClass(ReferentielId.class) // <- here
#Table(name = "Et_referentiel")
public class Referentiel implements Serializable {
// ...
}
Notice that it is required to have a class representing your composite keys, even if that does not help in your problem.
I'm using Spring Boot (1.3.3.RELEASE) and Hibernate JPA in my project. My entity looks like this:
#Data
#NoArgsConstructor
#Entity
#Table(name = "rule")
public class RuleVO {
#Id
#GeneratedValue
private Long id;
#Column(name = "name", length = 128, nullable = false, unique = true)
private String name;
#Column(name = "tag", length = 256)
private String tag;
#OneToMany(mappedBy = "rule", cascade = CascadeType.ALL, orphanRemoval = true)
private List<RuleOutputArticleVO> outputArticles;
#OneToMany(mappedBy = "rule", cascade = CascadeType.ALL, orphanRemoval = true)
private List<RuleInputArticleVO> inputArticles;
}
My repository looks like this:
#Repository
public interface RuleRepository extends JpaRepository<RuleVO, Long> {
}
In some cases I need to fetch only id and name attributes of entity RuleVO. How can I achieve this? I found a notice it should be doable using Criteria API and Projections but how? Many thanks in advance. Vojtech
UPDATE:
As has been pointed out to me, I'm lazy and this can very well be done hence I'm updating my answer after having looked around the web for a proper one.
Here's an example of how to get only the id's and only the names:
#Repository
public interface RuleRepository extends JpaRepository<RuleVO, Long> {
#Query("SELECT r.id FROM RuleVo r where r.name = :name")
List<Long> findIdByName(#Param("name") String name);
#Query("SELECT r.name FROM RuleVo r where r.id = :id")
String findNameById(#Param("id") Long id);
}
Hopefully this update proves helpful
Old Answer:
Only retrieving the specific attributes name/id is not possible as this is not how spring was designed or any SQL database for that matter as you always select a row which is an entity.
What you CAN do is query over the variables in the entity, for instance:
#Repository
public interface RuleRepository extends JpaRepository<RuleVO, Long> {
public RuleVo findOneByName(String name);
public RuleVo findOneByNameOrId(String name, Long id);
public List<RuleVo> findAllByName(String name);
// etc, depending on what you want
}
You can modify these however you want w.r.t. your needs. You can call these methods directly via the autowired repository
See http://docs.spring.io/spring-data/jpa/docs/current/reference/html/ Section 5.3 for more options and examples
interface IdOnly{
String getId();
}
#Repository
public interface RuleRepository extends JpaRepository<RuleVO, Long> {
public List<IdOnly> findAllByName(String name);
}
I notice that this is a very old post, but if someone is still looking for an answer, try this. It worked for me.
You can also define custom constructor to fetch specific columns using JPQL.
Example:
Replace {javaPackagePath} with complete java package path of the class
use as a constructor in JPQL.
public class RuleVO {
public RuleVO(Long id, String name) {
this.id = id;
this.name = name;
}
}
#Repository
public interface RuleRepository extends JpaRepository<RuleVO, Long> {
#Query("SELECT new {javaPackagePath}.RuleVO(r.id, r.name) FROM RuleVo r where r.name = :name")
List<RuleVO> findIdByName(#Param("name") String name);
}
Yes, you can achieve it with projections. You have many ways to apply them:
If you could upgrade to Spring Data Hopper, it provides an easy to use support for projections. See how to use them in the reference documentation.
Otherwise, first of all create a DTO with the attributes you want to load, something like:
package org.example;
public class RuleProjection {
private final Long id;
private final String name;
public RuleProjection(Long id, String name) {
this.id = id;
this.name = name;
}
public Long getId() {
return id;
}
public String getName() {
return name;
}
}
Of course, you could use Lombok annotations also.
Then, you can use in the JPQL queries like this:
select new org.example.RuleProjection(rule.id, rule.name) from RuleVO rule order by rule.name
Another option, if you want to avoid using DTO class names in your queries, is to implement your own query method using QueryDSL. With Spring Data JPA, you have to:
Create a new interface with the new method. Ex:
public interface RuleRepositoryCustom {
public List<RuleProjection> findAllWithProjection();
}
Change your repository to extend the new interface. Ex:
public interface RuleRepository extends JpaRepository<RuleVO, Long>, RuleRepositoryCustom {
...
Create an implementation of the Custom repository using the Spring Data JPA QueryDSL support. You have to previously generate the Q clases of QueryDSL, using its Maven plugin. Ex:
public class RuleRepositoryImpl {
public List<RuleProjection> findAllWithProjection() {
QRuleVO rule = QRuleVO.ruleVO;
JPQLQuery query = getQueryFrom(rule);
query.orderBy(rule.name.asc());
return query.list(ConstructorExpression.create(RuleProjection.class, rule.id, rule.name));
}
}
You can do it by using #Query annotation(HQL).
Please refer to the Spring docs below:
http://docs.spring.io/spring-data/jpa/docs/current/reference/html/#jpa.query-methods.at-query
(search for #Query in spring document)