QueryException：必须提供参考类

Question

我正在制定一个计划来整理我的无聊。我最近才开始，所以我还没有开始使用 GUI。该程序在视频/书籍上运行良好，但现在我添加了Game，我得到了queryException。有人知道我做错了什么吗？

错误：

原因：异常 [EclipseLink-6029] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.QueryException 异常说明：必须提供引用类。

发生错误的行：

public <E> List<E> getAll(Class<E> eClass){return manager.createQuery(manager.getCriteriaBuilder().createQuery(eClass)).getResultList(); }

不同实体类型调用该行的位置

for (Class eClass: Project.getAllItemTypes())
            repos.put(eClass, new Repository(persistenceAdministrator, eClass));

实体类型

public static Class[] getAllItemTypes(){
        return new Class[]{Movie.class, TvShow.class, ComedyShow.class, Book.class, Comicbook.class, Manga.class, Game.class};
    }

Game 和 Task 的 create-sql

CREATE TABLE Game(
    id INT NOT NULL AUTO_INCREMENT,
    stateStr VARCHAR(50) NOT NULL,
    title VARCHAR(100) NOT NULL,
    releaseDate DATE NOT NULL,
    gameId INT NULL,
  PRIMARY KEY (id),
  CONSTRAINT FK_gameId_game
    FOREIGN KEY (gameId)
    REFERENCES Game (id));

CREATE TABLE Task(
    id INT NOT NULL AUTO_INCREMENT,
    title VARCHAR(255) NOT NULL,
    completed BOOLEAN NOT NULL,
    gameId INT NOT NULL,
  PRIMARY KEY (id),
  CONSTRAINT FK_gameId_task
    FOREIGN KEY (gameId)
    REFERENCES Game (id));

游戏类：

@Entity
public class Game extends Item implements Serializable{

  @OneToMany
  private List<Game> children = new ArrayList<>();
  @OneToMany
  private List<Task> tasks = new ArrayList<>();
}

物品类别

@MappedSuperclass
public abstract class Item extends IEntity implements Serializable{

   @Transient
    private State state;
    @Column(nullable=false)
    private String stateStr;
    @Basic(optional = false)
    @Column(name = "releaseDate")
    @Temporal(TemporalType.DATE)
    private Calendar releaseDate;
    @Column(nullable=false)
    private String title;

IEntity 类

@MappedSuperclass
public abstract class IEntity extends Object implements Serializable{

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

持久性.xml

Answer 1

我找到了解决方案here

问题是这个方法：

public boolean isCompleted(){
        //return tasks.stream().allMatch((task) -> task.isCompleted());
        for (Task task: tasks) if (!task.isCompleted()) return false;
        return true;
    }

显然 JPA 实体类不适用于 java 8 lambdas。 我用老派 :P 代码替换了该方法，它可以工作。 无论如何，谢谢你帮助我。

Answer 2

通常定义自联接的方式类似于：

游戏

@Entity
public class Game extends Item implements Serializable{

  @ManyToOne
  @JoinColumn(name = "gameId")
  private Game parent;

  @OneToMany(mappedBy = "parent")
  private List<Game> children = new ArrayList<>();

  @OneToMany(mappedBy = "game")
  private List<Task> tasks = new ArrayList<>();
}

任务

@Entity
public class Task{

    @ManyToOne
    @JoinColumn(name = "gameId")
    private Game game;
}

别忘了@ManyToOne 映射在Task 一侧。