java - JPA + MySQL - 数据库生成的列值

Question

我正在使用带有 GENERATED ALWAYS AS 公式的列。当我尝试使用 JPA 保存实体值时，我得到

java.sql.SQLException: The value specified for generated column 'bucket' in table 'discover_cache' is not allowed.

类定义:

@Entity
@Getter
@NoArgsConstructor
@AllArgsConstructor
@Table(name = "discover_cache")
@IdClass(DiscoverCacheId.class)
public class DiscoverCache {

    @Id
    @Column(length = 36)
    private String userId;

    @Id
    private int postId;

    @Column(columnDefinition = "tinyint(4) GENERATED ALWAYS AS (floor(TO_SECONDS(`created_date`) / 900) % 17) STORED NOT NULL")
    @Id
    private short bucket;

    @CreatedDate
    @Column(name = "created_date", updatable = false, columnDefinition = "DATETIME(3)")
    @JsonIgnore
    private Instant createdDate = Instant.now();

    public DiscoverCache(String userId, int postId) {
        this.userId = userId;
        this.postId = postId;
    }
}

@EqualsAndHashCode
@NoArgsConstructor
public class DiscoverCacheId implements Serializable {

    @Column(length = 36)
    private String userId;

    private int postId;

    @Column(columnDefinition = "tinyint(4) GENERATED ALWAYS AS (floor(TO_SECONDS(`created_date`) / 900) % 17) STORED NOT NULL")
    private short bucket;

    public DiscoverCacheId(String userId, int postId, short bucket) {
        this.userId = userId;
        this.postId = postId;
        this.bucket = bucket;
    }
}

我如何告诉 JPA 在持久化时忽略这个值，以便我可以被数据库计算？我当然可以使用 native 查询来保存它，但我想使用 JpaRepository<>

Answer 1

将可插入和可更新设置为 false。

@Column(name="user_id", nullable = true, insertable = false, updatable = false)
var userId: Long? = null