Incorrect auto-generated SQL query in Spring Boot (JPA) CrudRepository

Question

My repository interfaces :

SongsRepository :

public interface SongRepository extends CrudRepository<Song, Integer> {
    
}

AlbumsRepository

public interface AlbumRepository extends CrudRepository<Album, Integer> {
    
}

---

My Model classes :

Album.java

@Entity
@Table(name = "albums", schema = "dbo")
public class Album {
    
    @Id
    @GeneratedValue
    @Column(name = "album_id")
    private Integer albumId;
    
    @Column(name = "album_name")
    private String albumName;
    
    @Column(name = "released_by")
    private String releasedBy;
    
    @Column(name = "total_duration")
    private Integer totalDuration;
    
    @OneToMany(targetEntity = Song.class)
    private List<Song> songs;

    public Integer getAlbumId() {
        return albumId;
    }

    public void setAlbumId(Integer albumId) {
        this.albumId = albumId;
    }

    public String getAlbumName() {
        return albumName;
    }

    public void setAlbumName(String albumName) {
        this.albumName = albumName;
    }

    public String getReleasedBy() {
        return releasedBy;
    }

    public void setReleasedBy(String releasedBy) {
        this.releasedBy = releasedBy;
    }

    public Integer getTotalDuration() {
        return totalDuration;
    }

    public void setTotalDuration(Integer totalDuration) {
        this.totalDuration = totalDuration;
    }

    public List<Song> getSongs() {
        return songs;
    }

    public void setSongs(List<Song> songs) {
        this.songs = songs;
    }
}

Song.java

@Entity
@Table(name = "songs", schema = "dbo")
public class Song {
    @Id
    @GeneratedValue
    @Column(name = "song_id")
    private Integer songId;

    @Column(name = "song_name")
    private String songName;
    
    @Column(name = "album_id")
    private Integer songAlbumId;
    
    @Column(name = "song_duration")
    private String songDuration;
    
    @ManyToOne(targetEntity = Album.class)
    private Album album;

    public Integer getSongId() {
        return songId;
    }

    public void setSongId(Integer songId) {
        this.songId = songId;
    }

    public String getSongName() {
        return songName;
    }

    public void setSongName(String songName) {
        this.songName = songName;
    }

    public Integer getSongAlbumId() {
        return songAlbumId;
    }

    public void setSongAlbumId(Integer songAlbumId) {
        this.songAlbumId = songAlbumId;
    }

    public String getSongDuration() {
        return songDuration;
    }

    public void setSongDuration(String songDuration) {
        this.songDuration = songDuration;
    }

    public Album getAlbum() {
        return album;
    }

    public void setAlbum(Album album) {
        this.album = album;
    }
}

---

My Controller :

SongsController.java

@RestController
@RequestMapping("/songs")
public class SongsController {
    
    @Autowired
    private SongRepository songs;
    
    @Autowired 
    private AlbumRepository albums;
    
    @Autowired
    private Services services;
    
    @GetMapping("/")
    public List<SongViewModel> getAllSongs() {
        List<SongViewModel> listOfAllSongs = new ArrayList<>();
        songs.findAll().forEach(song -> listOfAllSongs.add(services.translateToViewModel(song)));
        return listOfAllSongs;
    }
}

---

Services class :

Services.java :

@Service
public class Services {

    @Autowired
    private SongRepository songs;
    
    @Autowired
    private AlbumRepository albums;
    
    public SongViewModel translateToViewModel(Song song) {
        SongViewModel model = new SongViewModel();
        model.setSongId(song.getSongId());
        model.setSongAlbumId(song.getSongAlbumId());
        model.setSongName(song.getSongName());
        model.setSongDuration(song.getSongDuration());
        model.setSongAlbumName(albums.findById(song.getSongAlbumId()).get().getAlbumName());
        return model;
    }
    
    public AlbumViewModel translateToViewModel(Album album) {
        AlbumViewModel model = new AlbumViewModel();
        
        return model;
    }
}

---

My View Models :

SongViewModel :

public class SongViewModel {
    private String songName;
    private String songAlbumName;
    private String songDuration;
    private Integer songId;
    private Integer songAlbumId;
    public String getSongName() {
        return songName;
    }
    public void setSongName(String songName) {
        this.songName = songName;
    }
    public String getSongAlbumName() {
        return songAlbumName;
    }
    public void setSongAlbumName(String songAlbumName) {
        this.songAlbumName = songAlbumName;
    }
    public String getSongDuration() {
        return songDuration;
    }
    public void setSongDuration(String songDuration) {
        this.songDuration = songDuration;
    }
    public Integer getSongId() {
        return songId;
    }
    public void setSongId(Integer songId) {
        this.songId = songId;
    }
    public Integer getSongAlbumId() {
        return songAlbumId;
    }
    public void setSongAlbumId(Integer songAlbumId) {
        this.songAlbumId = songAlbumId;
    }
}

---

Logged SQL query :
select song0_.song_id as song_id1_1_, song0_.album_album_id as album_al5_1_, song0_.album_id as album_id2_1_, song0_.song_duration as song_dur3_1_, song0_.song_name as song_nam4_1_ from dbo.songs song0_

---

Error :
ERROR: column song0_.album_album_id does not exist

---

My Database Schema (PostgreSQL 12.10.1)

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This is my first time using Spring Boot and JPA. What have I done wrong here?

---

From the error message, I am guessing that it is trying to find a column called album_album_id which does not exist in my database and as a result is unable to find it; but why is it searching for that particular column? (My guess is I've messed up the relationship attributes).

Answer 1

Your Song entity class should be changed like follows.

@Entity
@Table(name = "songs", schema = "dbo")
public class Song {
    @Id
    @GeneratedValue
    @Column(name = "song_id")
    private Integer songId;

    @Column(name = "song_name")
    private String songName;
    
    @Column(name = "song_duration")
    private String songDuration;
    
    @JoinColumn(name = "album_id", referencedColumnName = "album_id")
    @ManyToOne
    private Album album;

    public Integer getSongId() {
        return songId;
    }

    public void setSongId(Integer songId) {
        this.songId = songId;
    }

    public String getSongName() {
        return songName;
    }

    public void setSongName(String songName) {
        this.songName = songName;
    }

    public Integer getSongAlbumId() {
        return songAlbumId;
    }

    public void setSongAlbumId(Integer songAlbumId) {
        this.songAlbumId = songAlbumId;
    }

    public String getSongDuration() {
        return songDuration;
    }

    public void setSongDuration(String songDuration) {
        this.songDuration = songDuration;
    }

    public Album getAlbum() {
        return album;
    }

    public void setAlbum(Album album) {
        this.album = album;
    }
}

now you can get alubm_id by song enntity using song.getAlbum().getAlbumId()

Answer 2

Your mapping is wrong. Song should look like this:

@Entity
@Table(name = "songs", schema = "dbo")
public class Song {
  @Id
  @GeneratedValue
  @Column(name = "song_id")
  private Integer id;

  @Column(name = "song_name")
  private String name;
    
  @Column(name = "album_id")
  private Integer albumId;
    
  @Column(name = "song_duration")
  private String duration;
    
  @ManyToOne
  @JoinColumn(name = "album_id", insertable = false, updatable = false)
  private Album album;
} 

and Album like this:

@Entity
@Table(name = "albums", schema = "dbo")
public class Album {
  @Id
  @GeneratedValue
  @Column(name = "album_id")
  private Integer id;
  
  @Column(name = "album_name")
  private String name;
  
  @Column(name = "released_by")
  private String releasedBy;
  
  @Column(name = "total_duration")
  private Integer totalDuration;
  
  @OneToMany(mappedBy = "album")
  private List<Song> songs;
}

---

By the way,

1. it's a little strange to have song duration formatted as String and album duration as Integer.
2. if you're willing to go from CrudRepository to JpaRepository, you may want to use Spring data projection instead of manually recasting your song to SongViewModels

Here's a little example of interface projection for your question