使用Hibernate注释映射PostgreSQL串行类型 [英] Mapping PostgreSQL serial type with Hibernate annotations
问题描述
我使用的是Hibernate 3.3和PostgreSQL 8.x,并且希望使用Hibernate注释映射一个不是主键的自动递增列。
只要数据库自动递增,而不是Hibernate自动递增,使用SERIAL类型或Postgres序列映射列是没有关系的。
@Column(name =orderId,insertable = false)我试过以下映射,但它们总是生成null orderId。
@Generated(GenerationTime.INSERT)
// @ GeneratedValue(strategy = javax.persistence.GenerationType.AUTO)
private Integer orderId;
我会很感激这方面的帮助。
感谢
以下映射应该可以正常工作:
@Column(name =orderId)
@Generated(GenerationTime.INSERT)
private Integer orderId;
但是,请注意,直到会话刷新后,新保存的对象的生成值才可用。注意,这个映射不会影响不会让Hibernate创建一个类型为的串行序列。
在模式生成过程中,因为Hibernate不知道数据库端的值生成性质。因此,如果你希望Hibernate创建一个适当类型的列,你需要明确指定它:
@Column(name =orderId,columnDefinition =serial)
@Generated(GenerationTime.INSERT)
private Integer orderId;
在最近的Hibernate版本(4.3)中,可以使用这个:
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long orderId;
I am using Hibernate 3.3 and PostgreSQL 8.x and would like to use Hibernate annotations to map an auto-incremented column which is NOT a primary key.
It doesn't matter if the column is mapped using SERIAL type or sequences in Postgres as long as it gets auto-incremented by the database and not by Hibernate. I tried the following mappings, but they always generated null orderId.
@Column(name = "orderId", insertable = false)
@Generated(GenerationTime.INSERT)
//@GeneratedValue(strategy = javax.persistence.GenerationType.AUTO)
private Integer orderId;
I will appreciate any help with this.
Thanks
The following mapping should work fine:
@Column(name = "orderId")
@Generated(GenerationTime.INSERT)
private Integer orderId;
Note, however, that generated value for freshly saved objects is not available until session is flushed.
EDIT: Note that this mapping doesn't affect doesn't make Hibernate to create a column of type serial
during schema generation, since Hibernate doesn't know anything about the nature of value generation at the database side. Therefore, if you want Hibernate to create a column with a proper type, you need to specifiy it explicitly:
@Column(name = "orderId", columnDefinition = "serial")
@Generated(GenerationTime.INSERT)
private Integer orderId;
And on a recent Hibernate version (4.3), you can use this:
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private Long orderId;
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