播放！2.2.1 Java Ebean-Finder.select（字符串列）不起作用：所有列均已选中

Question

I've got an issue with the select function of the Finder object by using ebean with Play! Framework (2.2.1).

I've got my table AnneePromotion :

CREATE TABLE AnneePromotion (
  anneePromotion_ID INTEGER NOT NULL PRIMARY KEY DEFAULT nextval('AnneePromotionSequence'),
  anneePromotion_libelle INTEGER NOT NULL 
);

My entity AnneePromotion :

@Entity
@Table(name = "AnneePromotion")
@SequenceGenerator(name = "AnneePromotionSequenceGenerator", sequenceName =         "AnneePromotionSequence")
public class AnneePromotion extends Model {

    /** serial ID */
    private static final long serialVersionUID = -2072489268439045171L;

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "AnneePromotionSequenceGenerator")
    @Column(name = "anneePromotion_ID")
    private Integer id;

    @Column(name = "anneePromotion_libelle")
    private String libelle;

    public Integer getId() {
        return id;
    }

    public String getLibelle() {
        return libelle;
    }

    public void setLibelle(String libelle) {
        this.libelle = libelle;
    }

    public static Finder<Integer, AnneePromotion> find = new Finder<Integer, AnneePromotion>(
        Integer.class, AnneePromotion.class);

}

And when I try to use the select function in order to just have libelle :

    List<AnneePromotion> listeDesAnneesdePromotion = AnneePromotionDao.find
            .select("libelle").orderBy("libelle asc").findList();
    for (AnneePromotion anneepromotion : listeDesAnneesdePromotion){
        System.out.println(anneepromotion.getId()+" "+anneepromotion.getLibelle());
    }

I received my objects with id and libelle columns :

1 2003
2 2004
3 2005
4 2006
5 2007
6 2008
7 2009
8 2010
9 2011
10 2012
11 2013
12 2014
13 2015
14 2016

I don't know with the select function doesn't work, if I made a stupid mistake or not :/

Hope you could help me.

Regards, Anthony.

Answer 1

That's common behavior of Ebean, reason is simple: you are asking for list of objects of concrete type, so it can't just return list of strings (without id ) as it need to identify rows somehow.

The simplest solution is rewriting it to new list ie.

List<String> libelles = new ArrayList<>();
for (AnneePromotion anneepromotion : listeDesAnneesdePromotion){
    libelles.add(anneepromotion.getLibelle());
}

Optionally you can also use Ebean's SqlQuery and then iterate through the list of SqlRow to get the same libelles list.