java - 当嵌入式键包含 SQL Server 上的标识列时，Hibernate 插入失败

Question

我正在尝试使用 hibernate 映射一个实体，但是使用 SQL Server，我无法继续。

详情如下。

SQL Server 实体

CREATE TABLE [dbo].[BOOK_EMBEDDED](

[row_id] [bigint] IDENTITY(1,1) NOT NULL,

[group_no] [int] NOT NULL,

[book_name] [varchar](255) NULL,

 CONSTRAINT [PK_BOOK_EMBEDDED] PRIMARY KEY CLUSTERED 

(

[group_no] ASC,

[row_id] ASC

)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]

) ON [PRIMARY]

=============================

嵌入 key

----------------------------

@Embeddable 

public class EmbeddedKey implements Serializable { 


    private static final long serialVersionUID = 1L; 



    @GeneratedValue(strategy = GenerationType.IDENTITY) 

    @Column(name = "row_id") 

    private Long rowId; 



    @Column(name = "group_no") 

    private int groupNo; 



    public Long getRowId() { 

        return rowId; 

    } 



    public void setRowId(Long rowId) { 

        this.rowId = rowId; 

    } 



    public static long getSerialversionuid() { 

        return serialVersionUID; 

    } 



    @Override 

    public int hashCode() { 

        final int prime = 31; 

        int result = 1; 

        result = (int) (prime * result + rowId); 

        result = prime * result + groupNo; 

        return result; 

    } 



    @Override 

    public boolean equals(Object obj) { 

        if (this == obj) 

            return true; 

        if (obj == null) 

            return false; 

        if (getClass() != obj.getClass()) 

            return false; 

        EmbeddedKey other = (EmbeddedKey) obj; 

        if (rowId != other.rowId) 

            return false; 

        if (groupNo != other.groupNo) 

            return false; 

        return true; 

    } 



    @Override 

    public String toString() { 

        return this.getRowId() + "  " + this.getGroupNo() + " "; 

    } 



    public int getGroupNo() { 

        return groupNo; 

    } 



    public void setGroupNo(int groupNo) { 

        this.groupNo = groupNo; 

    } 



} 

实体

----------------

@Entity(name = "BOOK_EMBEDDED") 

public class BookMySQL implements Serializable { 



    /** 

     *  

     */ 

    private static final long serialVersionUID = 1L; 



    @Column(name = "BOOK_NAME") 

    private String book_Name; 



    @EmbeddedId 

    private EmbeddedKey key; 



    public BookMySQL() { 

    } 



    public String getBook_Name() { 

        return book_Name; 

    } 



    public void setBook_Name(String book_Name) { 

        this.book_Name = book_Name; 

    } 



    public static long getSerialversionuid() { 

        return serialVersionUID; 

    } 



    public EmbeddedKey getKey() { 

        return key; 

    } 



    public void setKey(EmbeddedKey key) { 

        this.key = key; 

    } 



    @Override 

    public String toString() { 

        return this.getKey().toString() + "  " + this.getBook_Name(); 

    } 



} 

实体管理类

--------------------------------

public class LocalEntityManager { 

    private static EntityManagerFactory emf; 

    private static EntityManager em; 



    private LocalEntityManager() { 

    } 



    public static EntityManager getEntityManger() { 

        if (emf == null) { 

            synchronized (LocalEntityManager.class) { 

                if (emf == null) { 

                    emf = Persistence.createEntityManagerFactory("BookEntities"); 

                    em = emf.createEntityManager(); 

                } 

            } 

        } 

        return em; 

    } 

} 

图书服务

--------------------

public class MySQLBookService { 



    public Long persistBook(String bookName) { 

        EmbeddedKey key = new EmbeddedKey(); 

        key.setGroupNo(1); 



        BookMySQL book = new BookMySQL(); 

        book.setBook_Name(bookName); 

        book.setKey(key); 



        EntityManager em = LocalEntityManager.getEntityManger(); 

        EntityTransaction tx = em.getTransaction(); 

        tx.begin(); 

        em.persist(book); 

        tx.commit(); 

        em.close(); 



        return book.getKey().getRowId(); 

    } 



    public BookMySQL findBook(int bookId) { 

        EntityManager em = LocalEntityManager.getEntityManger(); 

        EmbeddedKey key = new EmbeddedKey(); 

        key.setGroupNo(1); 

        key.setRowId(1L); 

        BookMySQL bookMySQL = em.find(BookMySQL.class, key); 

        System.out.println(bookMySQL); 

        return bookMySQL; 

    } 



    public static void main(String... args) { 

        MySQLBookService bookService = new MySQLBookService(); 

        // bookService.findBook(1); 



        bookService.persistBook("Lord of the rings"); 

    } 



} 

问题是我不能使用序列并通过执行它findBook 始终有效并持续失败并出现错误。

ERROR: Cannot insert explicit value for identity column in table 'BOOK_EMBEDDED' when IDENTITY_INSERT is set to OFF.

任何帮助将不胜感激。

Answer 1

让它工作的唯一方法是覆盖 SQLInsert 并欺骗期望设置标识符列的 Hibernate。如果您提供自己的自定义 INSERT 语句，则可以这样做，而不是将 rowId 设置为 null，而是设置版本:

@Entity(name = "BOOK_EMBEDDED")
@SQLInsert( sql = "insert into BOOK_EMBEDDED (BOOK_NAME, group_no, version) values (?, ?, ?)")
public static class Book implements Serializable {

    @EmbeddedId
    private EmbeddedKey key;

    @Column(name = "BOOK_NAME")
    private String bookName;

    @Version
    @Column(insertable = false)
    private Integer version;

    public EmbeddedKey getKey() {
        return key;
    }

    public void setKey(EmbeddedKey key) {
        this.key = key;
    }

    public String getBookName() {
        return bookName;
    }

    public void setBookName(String bookName) {
        this.bookName = bookName;
    }
}

完成此更改后，您可以运行以下测试:

doInJPA(entityManager -> {

    EmbeddedKey key = new EmbeddedKey();
    key.setGroupNo(1);

    Book book = new Book();
    book.setBookName( "High-Performance Java Persistence");

    book.setKey(key);

    entityManager.persist(book);
});

doInJPA(entityManager -> {
    EmbeddedKey key = new EmbeddedKey();

    key.setGroupNo(1);
    key.setRowId(1L);

    Book book = entityManager.find(Book.class, key);
    assertEquals( "High-Performance Java Persistence", book.getBookName() );
});

Hibernate 将生成正确的 SQL 语句:

Query:["insert into BOOK_EMBEDDED (BOOK_NAME, group_no, version) values (?, ?, ?)"], Params:[(High-Performance Java Persistence, 1, NULL(BIGINT))]

Query:["select compositei0_.group_no as group_no1_0_0_, compositei0_.row_id as row_id2_0_0_, compositei0_.BOOK_NAME as BOOK_NAM3_0_0_, compositei0_.version as version4_0_0_ from BOOK_EMBEDDED compositei0_ where compositei0_.group_no=? and compositei0_.row_id=?"], Params:[(1, 1)]

测试可在 GitHub 上获得.