java - 涉及多个关联的 HQL JOIN

Question

我有三个实体，关系UserDetails hasmany FiledTask 和Task hasMany FiledTask。我想要的只是特定 User

的 FiledTask 列表

对于用户详细信息:

@OneToMany(mappedBy="user",cascade=CascadeType.ALL)
Collection<FiledTask> filedTasks = new ArrayList<FiledTask>();

对于我的任务

@OneToMany(mappedBy="task")
Collection<FiledTask> filedTasks = new ArrayList<FiledTask>();

而 FiledTask 看起来像

@ManyToOne
@JoinColumn(nullable = false, name = "taskId")
private Tasks task;
@ManyToOne
@JoinColumn(nullable = false, name = "userId")
private UserDetails user;

我试过了

query = session.createQuery("from Tasks as tasks inner join tasks.filedTasks as files with files.user = :user");
query.setParameter("user", user); //user is UserDetails instance

但是我得到错误子句can only reference columns in the driving table, means FiledTask can't userId for comparison?

with clause can only reference columns in the driving table [from com.akhi.app.cdm.Tasks as tasks inner join tasks.filedTasks as files with files.user = :user]

Answer 1

如果您想要给定用户的 FiledTasks，那么最简单的做法是

UserDetails user = session.find(UserDetails.class, userId);
Collection<FiledTask> filesTasks = user.getFiledTasks();

使用HQL，就是

select f from FiledTask f where f.user = :user

如果您想要的实际上是给定用户的任务，那么查询就可以简单地

select t from Tasks t
inner join t.filedTasks filedTask
where filedTask.user = :user

请注意，实体 Tasks 应命名为 Task。一个实例代表一个任务，而不是多个任务。