Question

我使用EclipseLink + PostgreSQL

我需要创建具有UUID（非主键）字段的空值的实体。

这是我的实体，字段 idUser 在某些情况下必须为null：

@Entity
@Table(schema = "bd00", name = "t_bd00_messages")
public class TBd00Messages implements Serializable {

@Id
@Column(name = "id")
@Getter @Setter
private UUID id;

@Getter @Setter
private String cdoc;

@Getter @Setter
private String receiver;

@Getter @Setter
private String message;

@Column(name = "status")
@Getter @Setter
private Integer statusCode;

@Temporal(TemporalType.TIMESTAMP)
@Getter @Setter
private Date tstmp;

@Column(name = "d_send")
@Temporal(TemporalType.TIMESTAMP)
@Getter @Setter
private Date dSend;

@Column(name = "id_user")
@Getter @Setter
private UUID idUser;

@Getter @Setter
private String subject;

当我持久化对象时， idUser = null - a有例外：

Internal Exception: org.postgresql.util.PSQLException: ERROR: column     "id_user" is of type uuid but expression is of type character varying
Hint: You will need to rewrite or cast the expression.
Position: 125
Error Code: 0
Call: INSERT INTO bd00.t_bd00_messages (id, CDOC, d_send, id_user, MESSAGE, RECEIVER, status, SUBJECT, TSTMP) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
bind => [********, *******, 2016-07-21 14:35:40.858, null, ......

Answer 1

对于基本映射，EclipseLink将传入null值并让驱动程序转换，这显然不能为UUID null做。

要解决这个问题，您需要告诉EclipseLink如何为驱动程序指定类型，如本文https://stackoverflow.com/a/15084881/496099中所示。关键部分是打电话

Field.setSqlType(Types.OTHER);
Field.setTypeName("uuid");
Field.setColumnDefinition("UUID");

在映射中使用的字段。

Answer 2

这将允许您将空值插入指定的列。

@Column(name = "id_user", nullable = true)

UUID列中的NULL值

2 个答案: