使用帶有Pageable的@Query通過JOIN FETCH獲取集合對象不起作用 - Spring JPA

Question

嘗試使用可分頁的 JOIN FETCH 獲取 Post 對象。 但它拋出異常。

實體

@Entity
public class Post {
  @Id
  private String postId;
  private String postName;
  @OneToMany(mappedBy = "Post", cascade = CascadeType.ALL)
  private Set<PostTag> postTags = new HashSet<PostTag>();
}
@Entity
public class Tag {
  @Id
  private String tagId;
  private String tagName;
  @OneToMany(mappedBy = "tag", cascade = CascadeType.ALL)
  @JsonIgnore
  private Set<PostTag> postTags = new HashSet<PostTag>();
}
@Entity
public class PostTag {
  @EmbeddedId
  private PostTagId postTagId = new PostTagId();
  
  @ManyToOne(fetch = FetchType.LAZY)
  @MapsId("postId")
  @JoinColumn(name = "post_Id")
  @JsonIgnore
  private Post post;
  
  @ManyToOne(fetch = FetchType.LAZY)
  @MapsId("tagId")
  @JoinColumn(name = "tag_Id")
  private Tag tag;
  
  @OneToMany(mappedBy = "posttag", cascade = CascadeType.ALL)
  @JsonIgnore
  private Set<Items> items= new HashSet<Items>();

  private String someDateField;
}
@Embeddable
public class PostTagId implements Serializable {
  private String postId;
  private String tagId;
  //equals & hashcode ommited
}
public class Items{
  @Id
  private String itemId;
  private String itemName;

  @ManyToOne(fetch = FetchType.LAZY)
  @JoinColumns({@JoinColumn(name = "post_id"), @JoinColumn(name = "tag_id")})
  @JsonBackReference
  @JsonIgnore
  private PostTag postTag;

  @OneToMany(mappedBy = "items", cascade = CascadeType.ALL)
  @JsonIgnore
  private Set<SubItems> subItems= new HashSet<SubItems>();

}
public class SubItems{
  @Id
  private String subItemId;
  private String subItemName;

  @ManyToOne(fetch = FetchType.LAZY)
  @JoinColumns({@JoinColumn(name = "itemId")})
  @JsonBackReference
  @JsonIgnore
  private Items items;

}

存儲庫查詢如下，

試過，

@Query(value = "select po from Post po INNER JOIN FETCH po.posttags pts INNER JOIN FETCH pts.tag t INNER JOIN FETCH pts.items i INNER JOIN FETCH i.subitems LEFT OUTER JOIN po.posttags pts2 where (t.tagName like :tName) and (pts.someDateField between :startDate and :endDate) order by pts2.someDateField desc", countQuery = "select count(po) from Post po INNER JOIN po.posttags pts INNER JOIN pts.tag t INNER JOIN pts.items i INNER JOIN i.subitems LEFT OUTER JOIN po.posttags pts2 where (t.tagName like :tName) and (pts.someDateField between :startDate and :endDate) order by pts2.someDateField desc")
Page<Post> findAllInOneQuery(String tName, String startDate, String endDate, Pageable pageable);

但這會導致以下異常。

Caused by: org.hibernate.QueryException: illegal attempt to dereference collection [po0_.postId.postTags] with element property reference [someDateField]

但是在 List 返回類型下面完美地工作。 為什么以及如何使用分頁？

@Query(value = "select po from Post po INNER JOIN FETCH po.posttags pts INNER JOIN FETCH pts.tag t INNER JOIN FETCH pts.items i INNER JOIN FETCH i.subitems LEFT OUTER JOIN po.posttags pts2 where (t.tagName like :tName) and (pts.someDateField between :startDate and :endDate) order by pts2.someDateField desc", countQuery = "select count(po) from Post po INNER JOIN po.posttags pts INNER JOIN pts.tag t INNER JOIN pts.items i INNER JOIN i.subitems LEFT OUTER JOIN po.posttags pts2 where (t.tagName like :tName) and (pts.someDateField between :startDate and :endDate) order by pts2.someDateField desc")
    List<Post> findAllInOneQuery(String tName, String startDate, String endDate);

為什么 List 按預期工作，但不是 Page 對象。 是否缺少任何參數，或者我是否需要稍微更改查詢以適應可分頁？

Answer 1

我讀了你的問題，這是我的建議：

要將 Peagable 與@Query注釋一起使用，您必須為您的 Query 指定 countBy 屬性。

@Query(
value = "select po from Post po INNER JOIN FETCH po.posttags pts INNER JOIN FETCH pts.tag t INNER JOIN FETCH pts.items i INNER JOIN FETCH i.subitems LEFT OUTER JOIN po.posttags pts2 where (t.tagName like :tName) and (pts.someDateField between :startDate and :endDate) order by pts2.someDateField desc", countQuery = "select count(po) from Post po INNER JOIN po.posttags pts INNER JOIN pts.tag t INNER JOIN pts.items i INNER JOIN i.subitems LEFT OUTER JOIN po.posttags pts2 where (t.tagName like :tName) and (pts.someDateField between :startDate and :endDate) order by pts2.someDateField desc",
countBy = "select count(po) from Post po INNER JOIN FETCH po.posttags pts INNER JOIN FETCH pts.tag t INNER JOIN FETCH pts.items i INNER JOIN FETCH i.subitems LEFT OUTER JOIN po.posttags pts2 where (t.tagName like :tName) and (pts.someDateField between :startDate and :endDate) order by pts2.someDateField desc", countQuery = "select count(po) from Post po INNER JOIN po.posttags pts INNER JOIN pts.tag t INNER JOIN pts.items i INNER JOIN i.subitems LEFT OUTER JOIN po.posttags pts2 where (t.tagName like :tName) and (pts.someDateField between :startDate and :endDate)")
Page<Post> findAllInOneQuery(String tName, String startDate, String endDate, Pageable pageable);