[英]JPA WHERE clause on many-to-many entity
I have two table, Book and Genre.我有两张桌子,书本和流派。 Each book may have many genre, and the many-to-many table only contain the Book ID and Genre ID.
每本书可能有多种流派,多对多表只包含书本 ID 和流派 ID。 I want to create a filter which would filter books by it's genre(s).
我想创建一个过滤器,它可以按类型过滤书籍。
@JoinTable(name = "bookGenre", joinColumns = {
@JoinColumn(name = "bookId", referencedColumnName = "id")}, inverseJoinColumns = {
@JoinColumn(name = "genreId", referencedColumnName = "id")})
@ManyToMany
private Collection<Genre> genreCollection;
Genre Class:类型 Class:
@Id
@Basic(optional = false)
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private Integer id;
@Size(max = 255)
@Column(name = "name")
private String name;
@Column(name = "status")
private Integer status;
@ManyToMany(mappedBy = "genreCollection")
private Collection<Book> bookCollection;
This is the query that I'm trying to do on JPA:这是我试图在 JPA 上执行的查询:
SELECT b.title FROM book b
JOIN bookGenre bg on bg.bookId = b.id
JOIN genre g on bg.genreId = g.id
WHERE g.id = 1
--Filter books that have genre with id 1
I've tried the following on JPA: SELECT b FROM Book b WHERE b.genreCollection.id = 1
我在 JPA 上尝试了以下操作:
SELECT b FROM Book b WHERE b.genreCollection.id = 1
But it gave me the following error: "The state field path 'b.genreCollection.id' cannot be resolved to a valid type."但它给了我以下错误:“state 字段路径 'b.genreCollection.id' 无法解析为有效类型。”
EDIT: I found out that i can use native sql query with built in result set mapping to Book POJO EntityManager.createNativeQuery(query, Book.class)
.编辑:我发现我可以使用原生 sql 查询和内置结果集映射到 Book POJO
EntityManager.createNativeQuery(query, Book.class)
。 So i just use that and string together my query with StringJoiner.所以我只是使用它并将我的查询与 StringJoiner 串在一起。
I think your JPA Query should be我认为您的 JPA 查询应该是
SELECT b FROM Book b INNER JOIN b.genreCollection g WHERE g.id = 1
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