JPA Join with childEntity.childForeignEntity - jpa

Question

I do not know how it is called in one word, but let me explain in details.
Lets assume I have following tables/schema in my database:
And following classes accordingly:
1.Post
#Entity
#Table(name = "posts")
public class Post {
#Id
private Long id;
#Column(name = "text")
private String text;
#OneToMany(fetch = FetchType.LAZY, mappedBy = "post")
private Set<PostComment> postComments = new HashSet<>();
}
2.Post Comments
#Entity
#Table(name = "post_comments")
public class PostComment {
#Id
private Long id;
#Column(name = "post_id")
private Long postId;
#Column(name = "user_id")
private Long userId;
#Column(name = "text")
private String text;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name="post_id")
private Post post;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name="user_id")
private User user;
}
3.User
#Entity
#Table(name = "users")
public class User {
#Id
private Long id;
#Column(name = "some_attributes")
private String someAttributes;
#OneToMany(fetch = FetchType.LAZY, mappedBy = "user")
private Set<PostComment> postComments = new HashSet<>();
}
How can I join Post with User via PostComment, so in my Post entity I could get all users commented:
#Entity
#Table(name = "posts")
public class Post {
....
//# join with post_comments.user_id
private Set<User> users = new HashSet<>();
....
}

Answer 1

Well, just get PostComment.user where PostComment.post equals your post.
#Query("select pc.user from PostComment pc where pc.post = :post")
List<User> getUsersWithComments(#Param("post") Post post);
Seems to work for me. Gives me the following SQL:
Hibernate: select user1_.id as id1_2_, user1_.some_attributes as some_att2_2_ from post_comments postcommen0_ inner join users user1_ on postcommen0_.user_id=user1_.id where postcommen0_.post_id=?
I don't know what this is all about:
#Column(name = "post_id")
private Long postId;
#Column(name = "user_id")
private Long userId;
or this
#JoinColumn(name="user_id")
#JoinColumn(name="post_id")
and you shouldn't do this:
= new HashSet<>();
and while we're at it this is redundant.
fetch = FetchType.LAZY,