I am using Spring JPA to perform all database operations. However I don't know how to select specific columns from a table in Spring JPA?
For example:
SELECT projectId, projectName FROM projects
You can use projections from Spring Data JPA (doc). In your case, create interface:
interface ProjectIdAndName{
String getId();
String getName();
}
and add following method to your repository
List<ProjectIdAndName> findAll();
I don't like the syntax particularly (it looks a little bit hacky...) but this is the most elegant solution I was able to find (it uses a custom JPQL query in the JPA repository class):
#Query("select new com.foo.bar.entity.Document(d.docId, d.filename) from Document d where d.filterCol = ?1")
List<Document> findDocumentsForListing(String filterValue);
Then of course, you just have to provide a constructor for Document that accepts docId & filename as constructor args.
You can set nativeQuery = true in the #Query annotation from a Repository class like this:
public static final String FIND_PROJECTS = "SELECT projectId, projectName FROM projects";
#Query(value = FIND_PROJECTS, nativeQuery = true)
public List<Object[]> findProjects();
Note that you will have to do the mapping yourself though. It's probably easier to just use the regular mapped lookup like this unless you really only need those two values:
public List<Project> findAll()
It's probably worth looking at the Spring data docs as well.
In my situation, I only need the json result, and this works for me:
public interface SchoolRepository extends JpaRepository<School,Integer> {
#Query("select s.id, s.name from School s")
List<Object> getSchoolIdAndName();
}
in Controller:
#Autowired
private SchoolRepository schoolRepository;
#ResponseBody
#RequestMapping("getschoolidandname.do")
public List<Object> getSchool() {
List<Object> schools = schoolRepository.getSchoolIdAndName();
return schools;
}
With the newer Spring versions One can do as follows:
If not using native query this can done as below:
public interface ProjectMini {
String getProjectId();
String getProjectName();
}
public interface ProjectRepository extends JpaRepository<Project, String> {
#Query("SELECT p FROM Project p")
List<ProjectMini> findAllProjectsMini();
}
Using native query the same can be done as below:
public interface ProjectRepository extends JpaRepository<Project, String> {
#Query(value = "SELECT projectId, projectName FROM project", nativeQuery = true)
List<ProjectMini> findAllProjectsMini();
}
For detail check the docs
In my case i created a separate entity class without the fields that are not required (only with the fields that are required).
Map the entity to the same table.
Now when all the columns are required i use the old entity, when only some columns are required, i use the lite entity.
e.g.
#Entity
#Table(name = "user")
Class User{
#Column(name = "id", unique=true, nullable=false)
int id;
#Column(name = "name", nullable=false)
String name;
#Column(name = "address", nullable=false)
Address address;
}
You can create something like :
#Entity
#Table(name = "user")
Class UserLite{
#Column(name = "id", unique=true, nullable=false)
int id;
#Column(name = "name", nullable=false)
String name;
}
This works when you know the columns to fetch (and this is not going to change).
won't work if you need to dynamically decide the columns.
In my opinion this is great solution:
interface PersonRepository extends Repository<Person, UUID> {
<T> Collection<T> findByLastname(String lastname, Class<T> type);
}
and using it like so
void someMethod(PersonRepository people) {
Collection<Person> aggregates =
people.findByLastname("Matthews", Person.class);
Collection<NamesOnly> aggregates =
people.findByLastname("Matthews", NamesOnly.class);
}
I guess the easy way may be is using QueryDSL, that comes with the Spring-Data.
Using to your question the answer can be
JPAQuery query = new JPAQuery(entityManager);
List<Tuple> result = query.from(projects).list(project.projectId, project.projectName);
for (Tuple row : result) {
System.out.println("project ID " + row.get(project.projectId));
System.out.println("project Name " + row.get(project.projectName));
}}
The entity manager can be Autowired and you always will work with object and clases without use *QL language.
As you can see in the link the last choice seems, almost for me, more elegant, that is, using DTO for store the result. Apply to your example that will be:
JPAQuery query = new JPAQuery(entityManager);
QProject project = QProject.project;
List<ProjectDTO> dtos = query.from(project).list(new QProjectDTO(project.projectId, project.projectName));
Defining ProjectDTO as:
class ProjectDTO {
private long id;
private String name;
#QueryProjection
public ProjectDTO(long projectId, String projectName){
this.id = projectId;
this.name = projectName;
}
public String getProjectId(){ ... }
public String getProjectName(){....}
}
Using Spring Data JPA there is a provision to select specific columns from database
---- In DAOImpl ----
#Override
#Transactional
public List<Employee> getAllEmployee() throws Exception {
LOGGER.info("Inside getAllEmployee");
List<Employee> empList = empRepo.getNameAndCityOnly();
return empList;
}
---- In Repo ----
public interface EmployeeRepository extends CrudRepository<Employee,Integer> {
#Query("select e.name, e.city from Employee e" )
List<Employee> getNameAndCityOnly();
}
It worked 100% in my case.
Thanks.
You can use JPQL:
TypedQuery <Object[]> query = em.createQuery(
"SELECT p.projectId, p.projectName FROM projects AS p", Object[].class);
List<Object[]> results = query.getResultList();
or you can use native sql query.
Query query = em.createNativeQuery("sql statement");
List<Object[]> results = query.getResultList();
You can apply the below code in your repository interface class.
entityname means your database table name like projects.
And List means Project is Entity class in your Projects.
#Query(value="select p from #{#entityName} p where p.id=:projectId and p.projectName=:projectName")
List<Project> findAll(#Param("projectId") int projectId, #Param("projectName") String projectName);
It is possible to specify null as field value in native sql.
#Query(value = "select p.id, p.uid, p.title, null as documentation, p.ptype " +
" from projects p " +
"where p.uid = (:uid)" +
" and p.ptype = 'P'", nativeQuery = true)
Project findInfoByUid(#Param("uid") String uid);
You can use the answer suggested by #jombie, and:
place the interface in a separate file, outside the entity class;
use native query or not (the choice depended on your needs);
don't override findAll() method for this purpose but use name of your choice;
remember to return a List parametrized with your new interface (e.g. List<SmallProject>).
Using Native Query:
Query query = entityManager.createNativeQuery("SELECT projectId, projectName FROM projects");
List result = query.getResultList();
public static final String FIND_PROJECTS = "select ac_year_id,ac_year from tbl_au_academic_year where ac_year_id=?1";
#Query(value = FIND_PROJECTS, nativeQuery = true)
public List<Object[]> findByAcYearId(Integer ac_year_id);
this works for me
You can update your JPARepository as below.
#Query("select u.status from UserLogin u where u.userId = ?1 or u.email = ?1 or u.mobile = ?1")
public UserStatus findByUserIdOrEmailOrMobile(String loginId);
Where UserStatus is a Enum
public enum UserStatus
{
New,
Active,
Deactived,
Suspended,
Locked
}
Use:
#Query("SELECT e FROM #{#entityName} e where e.userId=:uid")
List<ClienteEnderecoEntity> findInfoByUid(#Param("uid") UUID uid);
{
"Comments":"Why not using JDBCTemplate",
"Url":"https://www.baeldung.com/spring-jdbc-jdbctemplate"
}
I have an entity class and repository. Here I'm trying to execute update query but not working.
How to update Lob column in native query or any another solution on jpa query to update Lob column.
#Entity
#Table(name = "comment")
public class Comment implements Serializable {
#Basic
#Lob
#Column(name="Article_COMMENT", columnDefinition="TEXT")
private String articleComment;
#Basic
#Column(name = "ID_ARTICLE")
private Long articleId;
}
#Repository
public interface commentRepository extends JpaRepository<Comment, Long> {
#Query(value = "UPDATE comment set articleComment=: articleComment WHERE articleId =: articleId", nativeQuery=true)
void updateComment(#Param("articleComment") String articleComment, #Param("articleId") Long articleId );
}
Error:
No results were returned by query.
JpaSystemException thrown with message: could not extract ResultSet; nested exception is org.hibernate.exception.GenericJDBCException: could not extract ResultSet
Your question is very vague so I can answer on assumptions only. I think You want to update the articalComment field of your Entity. You can simply use .save() method of JpaRepository. Your code should be as follows. Here I am also assuming that your articleId is unique identifier to your entity class.
#Entity
#Table(name = "comment")
public class Comment implements Serializable {
#Basic
#Lob
#Column(name="Article_COMMENT", columnDefinition="TEXT")
private String articleComment;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "ID_ARTICLE")
private Long articleId;
}
Now your Id should be unique and has a #Id Annotation to identify it inside spring data JPA.
You don't have to add any code inside of your JPA repository. Simply call commentRepository.save(commentObject) method. If commentObject has an ID as 0 then a new Comment will be created. If the ID is a positive value and is present in your table that particular row will be updated not created.
remove the space try this way
UPDATE comment set articleComment=:articleComment WHERE articleId =:articleId
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
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