Exception when selecting specific columns using Hibernate and Spring Data JPA - postgresql

Question

I have a table that has a bytea column (named 'pdf') and I don't want to always select it, specially when I'm returning a list from the database, due to performance issues.
I use native queries with spring data inside the repository to solve these types of situations before (when I used eclipselink), but with Hibernate, if I don't write all the columns in the query, it throws an exception.
For test purposes, I'm trying to select only the id from the User and I still get the exception.
Example: "SELET user.id FROM user WHERE user.id = '1'"
It throws an exception saying that it did not find name in the ResultSet, if I put name in the SQL, it then says age was not found and so on, until I have to write all the columns in the SQL.
Thanks in advance for any help.
What I have tried already:
Updating/Downgrading Hibernate and Spring Data with no luck.
Creating a new entity with only the columns I need, works, but it's a messy solution for me.
Maybe the problem is the combination of the frameworks I use and the way I use them, if someone wants, I could try to upload my whole project structure.
My code:
Entity
#Entity
#Table(name = "user", schema = "portal")
public class User implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Basic(optional = false)
#Column(name = "id")
private Integer id;
#Column(name = "pdf")
private byte[] pdf;
#Column(name = "name")
private String name;
#Column(name = "age")
private Integer age;
public User() {
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public byte[] getPdf() {
return pdf;
}
public void setPdf(byte[] pdf) {
this.pdf = pdf;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
#Override
public int hashCode() {
int hash = 0;
hash += (id != null ? id.hashCode() : 0);
return hash;
}
#Override
public boolean equals(Object object) {
// TODO: Warning - this method won't work in the case the id fields are not set
if (!(object instanceof Anexo)) {
return false;
}
Anexo other = (Anexo) object;
if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
return false;
}
return true;
}
#Override
public String toString() {
return "br.gov.to.secad.portal.domain.User[ id=" + id + " ]";
}
}
Service
#Service
#Transactional(readOnly = true)
public class UserService implements Serializable {
private static final long serialVersionUID = 1L;
#Autowired
private IUserRepository userRepository;
public UserService() {
}
public User findOne() {
return userRepository.findOneSQL();
}
}
Repository
public interface IUserRepository extends JpaRepository<User, Serializable>, JpaSpecificationExecutor {
#Query(value = "SELECT user.id FROM user WHERE user.id = '1'", nativeQuery = true)
public User findOneSQL();
}
The exception:
org.postgresql.util.PSQLException: The column name name was not found in this ResultSet.
Solution
The solution is using an array of Object when I want to select anything less than what I've mapped on my Entity class, thats the limitation of Hibernate that I now understand.
So basically, the method will return Object[] and then I can iterate each position and instantiate a new entity of User with these values.
Example:
#Query(value = "SELECT user.id FROM user WHERE user.id = '1'", nativeQuery = true)
public Object[] findOneSQL();

Answer 1

I have faced the same problem, I know it is late but well there is a solution that I found elegant.
By the Spring documentation you can declare an interface and from here take the fields you want, in my case it has been something similar to this.
The interface to minimize the fields:
public interface CountryMinify {
String getName();
String getNameTranslation();
}
And my JpaRepository
public interface PlanetRepository extends JpaRepository<Planet, Long> {
#Query(value = "select p.name_country as name, p.name_country_translation as nameTranslation from vm_planet p where gid = ?1", nativeQuery = true)
CountryMinify findByCode(String codeCountry);
}
Keep in mind that the columns should be called the same as gos getter. For example: column name_country -> AS name and the getter of the interface is getName()

Answer 2

Try this
#Query(value = "SELECT user.id FROM user WHERE user.id = '1'", nativeQuery = true)
Integer findOneSQL();
Call the method like so
Integer user = userRepository.findOneSQL();
Edit 1 :
Since you are using native query you wont be able to use Projections which is a great way of accessing only certain entity fields. There is a JIRA ticket which is still under investigation.
Solution
Return List from your repository like so
#Query(value = "SELECT user.id, user.name FROM user WHERE user.id = '1'", nativeQuery = true)
List<Object[]> findOneSQL();
Iterate over the list of Objects and get your specific columns.
List<Object[]> userNative = userRepository.findOneSQL();
for (Object[] obj : userNative) {
System.out.println("User id : " + obj[0]);
System.out.println("User Name : " + obj[1]);
}