Java Jpa查詢搜索實體相關ID

Question

我有2個實體：作者和專輯。 作者是OneToMany（mappedby =「author」） 相冊是ManyToOne

我試圖搜索相冊idAuthor傳遞。

下面的代碼：

public Collection<Album> findByIdAuthor(Long idAuthor, HttpServletRequest request) { 
    Collection<Album> album; 
    try { 
     album = em.createQuery("select a from Album a where a.author like :id").setParameter("id", idAuthor).getResultList(); 
    } catch(Exception e) { 
     request.setAttribute("err", e.toString()); 
     return null; 
    } 
    return album; 
} 

而且這裏有作者實體

@Entity 
public class Author { 
@Id 
@GeneratedValue(strategy = GenerationType.AUTO) 
private Long id; 

@Column(nullable=false) 
private String name; 

@Column 
private int debut; 

@Column(length=1000) 
private String info; 

@OneToMany(mappedBy="author") 
private List<Track> tracks; 

@OneToMany(mappedBy="author",cascade={CascadeType.PERSIST,CascadeType.MERGE,CascadeType.REFRESH}) 
private List<Album> album; 

public Author() { 
    super(); 
} 

public Author(String name) { 
    super(); 
    this.name = name; 
} 

public Long getId() { 
    return id; 
} 

public void setId(Long id) { 
    this.id = id; 
} 

public String getName() { 
    return name; 
} 

public void setName(String name) { 
    this.name = name; 
} 

public int getDebut() { 
    return debut; 
} 

public void setDebut(int debut) { 
    this.debut = debut; 
} 

public String getInfo() { 
    return info; 
} 

public void setInfo(String info) { 
    this.info = info; 
} 

public List<Track> getTracks() { 
    return tracks; 
} 

public void setTracks(List<Track> tracks) { 
    this.tracks = tracks; 
} 

public List<Album> getAlbum() { 
    return album; 
} 

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

@Override 
public String toString() { 
    return "Autore [id=" + id + ", nome=" + name + ", dataDebutto=" 
      + debut + ", info=" + info + ", brani=" + tracks 
      + ", album=" + album + "]"; 
} 

}

但我收到此：org.apache.openjpa.persistence.ArgumentException：沒有元數據找到類型爲「java.lang.Integer」的類。該課程沒有增強。
爲什麼？

Answer 1

您正在嘗試發送整數值對象

你說，作者（對象），如ID（idAuthor龍）

更正如下嘗試

public Collection<Album> findByIdAuthor(Long idAuthor, HttpServletRequest request) { 
    Collection<Album> album; 
    try { 
     album = em.createQuery("select a from Album a where a.author.id like :id").setParameter("id", idAuthor).getResultList(); 
    } catch(Exception e) { 
     request.setAttribute("err", e.toString()); 
     return null; 
    } 
    return album; 
}