Mapping NativeQuery results into a POJO

问题:

I am attempting to map the results of a Native query to a POJO using @SqlResultSetMapping with @ConstructorResult. Here is my code:

@SqlResultSetMapping(name="foo",
    classes = {
        @ConstructorResult(
                targetClass = Bar.class,
                columns = {
                    @ColumnResult(name = "barId", type = Long.class),
                    @ColumnResult(name = "barName", type = String.class),
                    @ColumnResult(name = "barTotal", type = Long.class)
                })
    })

public class Bar {

private Long barId;
private String barName;
private Long barTotal;

...

And then in my DAO:

Query query = em.createNativeQueryBar(QUERY, "foo");
... set some parameters ...
List<Bar> list = (List<Bar>) query.getResultList();

I have read that this functionality is only supported in JPA 2.1, but that is what I am using. Here's my dependency:

        <dependency>
            <groupId>org.hibernate.javax.persistence</groupId>
            <artifactId>hibernate-jpa-2.1-api</artifactId>
            <version>1.0.0.Final</version>
        </dependency>

I found a couple of resources, including this one: @ConstructorResult mapping in jpa 2.1. But I am still not having any luck.

What am I missing? Why can't the SqlResultSetMapping be found?

javax.persistence.PersistenceException: org.hibernate.MappingException: Unknown SqlResultSetMapping [foo]

回答1:

@SqlResultSetMapping annotation should not be put on a POJO. Put it at (any) @Entity class. "Unknown SqlResultSetMapping [foo]" tells you, that JPA provider doesn't see any mapping under name 'foo'. Please see another answer of mine for the correct example

• JPA- Joining two tables in non-entity class

回答2:

Short working example:

• DTO POJO class

  @lombok.Getter
  @lombok.AllArgsConstructor
  public class StatementDto {
      private String authorName;
      private Date createTime;
  }
  

• Repository bean:

  @Repository
  public class StatementNativeRepository {      
      @PersistenceContext private EntityManager em;
  
      static final String STATEMENT_SQLMAP = "Statement-SQL-Mapping";
  
      public List<StatementDto> findPipelinedStatements() {
          Query query = em.createNativeQuery(
              "select author_name, create_time from TABLE(SomePipelinedFun('xxx'))",
              STATEMENT_SQLMAP);
          return query.getResultList();
      }
  
      @SqlResultSetMapping(name= STATEMENT_SQLMAP, classes = {
          @ConstructorResult(targetClass = StatementDto.class,
              columns = {
                  @ColumnResult(name="author_name",type = String.class),
                  @ColumnResult(name="create_time",type = Date.class)
              }
          )
      }) @Entity class SQLMappingCfgEntity{@Id int id;} // <- walkaround
  
  }
  

回答3:

I able to do it this way:

Session session = em().unwrap(Session.class);
SQLQuery q = session.createSQLQuery("YOUR SQL HERE");
q.setResultTransformer( Transformers.aliasToBean( MyNotMappedPojoClassHere.class) );
List<MyNotMappedPojoClassHere> postList = q.list();

回答4:

@Entity
@SqlResultSetMapping(name="ConnexionQueryBean",
   entities={
         @EntityResult(entityClass=com.collecteJ.business.bean.ConnexionQueryBean.class, fields={ 
        @FieldResult(name="utilisateurId", column="UTILISATEUR_ID"),
        @FieldResult(name="nom", column="NOM"),
        @FieldResult(name="prenom", column="PRENOM"),
        @FieldResult(name="nomConnexion", column="NOM_CONNEXION"),
        @FieldResult(name="codeAgence", column="CODE_AGENCE"),
        @FieldResult(name="codeBanque", column="CODE_BANQUE"),
        @FieldResult(name="codeDevise", column="CODE_DEVISE"),
        @FieldResult(name="codeCollecteur", column="CODE_COLLECTEUR")})
   })
public class ConnexionQueryBean implements Serializable {

@Id
private long utilisateurId;
private String codeCollecteur;
private String nom;
private String prenom;
private String nomConnexion; 
private String codeAgence;
private String codeBanque;
private String codeDevise;


public ConnexionQueryBean() {
}


public long getUtilisateurId() {
    return utilisateurId;
}

public void setUtilisateurId(long utilisateurId) {
    this.utilisateurId = utilisateurId;
}

public String getCodeCollecteur() {
    return codeCollecteur;
}

public void setCodeCollecteur(String codeCollecteur) {
    this.codeCollecteur = codeCollecteur;
}


public String getNom() {
    return nom;
}

public void setNom(String nom) {
    this.nom = nom;
}

public String getPrenom() {
    return prenom;
}

public void setPrenom(String prenom) {
    this.prenom = prenom;
}

public String getNomConnexion() {
    return nomConnexion;
}

public void setNomConnexion(String nomConnexion) {
    this.nomConnexion = nomConnexion;
}

public String getCodeAgence() {
    return codeAgence;
}

public void setCodeAgence(String codeAgence) {
    this.codeAgence = codeAgence;
}

public String getCodeBanque() {
    return codeBanque;
}

public void setCodeBanque(String codeBanque) {
    this.codeBanque = codeBanque;
}

public String getCodeDevise() {
    return codeDevise;
}

public void setCodeDevise(String codeDevise) {
    this.codeDevise = codeDevise;
}

@Override
public String toString() {
    return "ConnexionQueryBean{" + "utilisateurId=" + utilisateurId + ", codeCollecteur=" + codeCollecteur + ", nom=" + nom + ", prenom=" + prenom + ", nomConnexion=" + nomConnexion + ", codeAgence=" + codeAgence + ", codeBanque=" + codeBanque + ", codeDevise=" + codeDevise + '}';
}

This is not really an entity as it does not match any database table. But the @Entity and the @Id annotations are compulsories for JPA to understand the mapping. If you don't really want to have @Entity / @Id in that class, you can remove the @SqlResultSetMapping annotation and put it in any other entity as far as JPA can scan it.

You should also make sure that your @ComponentScan content the corresponding package, if you are using a java based spring configuration, you should explicitly declare your entity in the persistence.xml/orm.xml under the META-INF directory.

This is the call

String connexionQuery = "SELECT u.UTILISATEUR_ID, u.NOM, u.PRENOM, u.NOM_CONNEXION, a.CODE_AGENCE, a.CODE_BANQUE, a.CODE_DEVISE, c.CODE_COLLECTEUR FROM UTILISATEUR u, AGENCE a, COLLECTEUR c "
            + " WHERE (a.CODE_AGENCE = c.CODE_AGENCE AND u.UTILISATEUR_ID = c.UTILISATEUR_ID AND u.NOM_CONNEXION = '"+nomConnextion+"')";

    ConnexionQueryBean ConnexionResults = (ConnexionQueryBean) defaultService.getEntityManager().createNativeQuery(connexionQuery,"ConnexionQueryBean").getSingleResult();
    System.out.println(ConnexionResults.toString());

I'm using Spring, JPA 2.1, Hibernate 5 and Oracle, i think this might not be possible with JPA lower version, find more http://www.thoughts-on-java.org/result-set-mapping-complex-mappings/

回答5:

QLRM could be a alternative: http://simasch.github.io/qlrm/

It is not related to a specific JPA implementation and also works with JDBC.

回答6:

I have a slightly varied answer which is just derived from wildloop's answer.
Here is my answer:

Constants class: Constants.java

public class Constants {
    public final String TESTQUERYRESULT_MAPPING_NAME = "TestQueryResultMapping";
}

Result Mapping Class: TestQueryResult.java

import lombok.Getter;
import lombok.Setter;

import javax.persistence.Entity;
import javax.persistence.EntityResult;
import javax.persistence.FieldResult;
import javax.persistence.Id;
import javax.persistence.SqlResultSetMapping;

@Getter
@Setter
@SqlResultSetMapping(
    //name = "TestQueryResultMapping"
    name = Constants.TESTQUERYRESULT_MAPPING_NAME
    ,entities = @EntityResult(
        entityClass = TestQueryResult.class
        ,fields = {
            @FieldResult(name = "rowId", column = "row_id")
            ,@FieldResult(name = "rowName", column = "row_name")
            ,@FieldResult(name = "value", column = "row_value")
        }
    )
)
@Entity
public class TestQueryResult {
    @Id
    private Integer rowId;

    private String rowName;

    private String value;

}

Then... somewhere in my Repository Implementation code:

public class TestQueryRepository {
    //... some code here to get the entity manager here

    public TestQueryResult getTopMost(Integer rowName) {
        //... some code here

        String queryString = "... some query string here" + rowName;
        TestQueryResult testQueryResult = null;

        //this.entityManager.createNativeQuery(queryString ,"TestQueryResultMapping").getResultList();
        List<TestQueryResult> results = this.entityManager.createNativeQuery(queryString ,Constants.TESTQUERYRESULT_MAPPING_NAME).getResultList();
        if (results != null && !results.isEmpty()) {
            testQueryResult = results.get(0);
        }

        return testQueryResult;
    }

}

... then violah! I got some results :D!

Cheers,
Artanis Zeratul