java 如何让 created_at 列像自动创建 ID 一样自动生成创建日期时间？
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How can you make a created_at column generate the creation date-time automatically like an ID automatically gets created?
提问by Brett Freeman
I currently have an Entity as below:
我目前有一个实体如下：
@Entity
public class Product {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long productId;
private String productImage;
private String productTitle;
private String productDescription;
private Integer productPrice;
private Date createdAt;
private Date updatedAt;
Upon creation of this object, the value of createdAt and updatedAt shows null in the database and was wondering how I can implement code so that createdAt and updateAt automatically gets inserted?
创建此对象后，createdAt 和 updatedAt 的值在数据库中显示为 null，我想知道如何实现代码以便自动插入 createdAt 和 updateAt？
My post method is as below:
我的post方法如下：
@PostMapping("/products")
public ProductResponse createProduct(@Validated @RequestBody ProductForm productForm) {
Product product = productForm.asProduct();
Product createdProduct = productRepository.save(product);
return new ProductResponse(createdProduct, "Product created");
}
回答by dimitrisli
JPA
日本特许经营协会
There isn't anything as convenient as annotating the Timestamp field directly but you could use the @PrePersist, @PreUpdateannotations and with little effort achieve the same results.
没有什么比直接注释 Timestamp 字段更方便的了，但是您可以使用@PrePersist,@PreUpdate注释并且毫不费力地获得相同的结果。
Hibernate
休眠
@CreationTimestamp- Documentation@UpdateTimestamp- Documentation
Spring Data JPA
弹簧数据 JPA
@CreatedDate- Documentation@LastModifiedDate- Documentation
回答by buddha
You can create a BaseEntity. Each entity extends the BaseEntity. In the Base entity ,it will set the time automatically
您可以创建一个 BaseEntity。每个实体都扩展了 BaseEntity。在 Base 实体中，它会自动设置时间
@Data
@MappedSuperclass
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public abstract class BaseEntity implements Serializable {
@Id
@Column(name = "Id")
private String id;
@Column(name = "deleted", columnDefinition = "Bit(1) default false")
private boolean deleted = false;
@Column(name = "DataChange_CreatedBy", nullable = false)
private String dataChangeCreatedBy;
@Column(name = "DataChange_CreatedTime", nullable = false)
private Date dataChangeCreatedTime;
@Column(name = "DataChange_LastModifiedBy")
private String dataChangeLastModifiedBy;
@Column(name = "DataChange_LastTime")
private Date dataChangeLastModifiedTime;
@PrePersist
protected void prePersist() {
if (this.dataChangeCreatedTime == null) dataChangeCreatedTime = new Date();
if (this.dataChangeLastModifiedTime == null) dataChangeLastModifiedTime = new Date();
}
@PreUpdate
protected void preUpdate() {
this.dataChangeLastModifiedTime = new Date();
}
@PreRemove
protected void preRemove() {
this.dataChangeLastModifiedTime = new Date();
}
}
回答by Sarvar Nishonboev
Extend the following abstract class in your entity:
在您的实体中扩展以下抽象类：
@MappedSuperclass
@EntityListeners(AuditingEntityListener.class)
public abstract class DateAudit implements Serializable {
@CreatedDate
@Column(name = "created_at", nullable = false, updatable = false)
private Date createdAt;
@LastModifiedDate
@Column(name = "updated_at")
private LocalDateTime updatedAt;
}
Don't forget to enable JPA Auditing feature using @EnableJpaAuditing
不要忘记使用启用 JPA 审计功能 @EnableJpaAuditing
Read this: https://docs.spring.io/spring-data/jpa/docs/1.7.0.DATAJPA-580-SNAPSHOT/reference/html/auditing.html
阅读：https: //docs.spring.io/spring-data/jpa/docs/1.7.0.DATAJPA-580-SNAPSHOT/reference/html/auditing.html
回答by Francis Robitaille
With the mix of @dimitrisli and @buddha answers, something pretty clean is
结合@dimitrisli 和@buddha 的答案，一些非常干净的东西是
@Data
@MappedSuperclass
public abstract class BaseEntity {
@Column(updatable = false)
@CreationTimestamp
private LocalDateTime createdAt;
@UpdateTimestamp
private LocalDateTime updatedAt;
}
And now you all your entity can extend that class like so
现在你所有的实体都可以像这样扩展那个类
@Data
@Entity
@EqualsAndHashCode(callSuper = true)
public class User extends BaseEntity {
@Id
@GeneratedValue
public UUID id;
public String userName;
public String email;
public String firstName;
public String lastName;
}
Note that you might not need @Data& @EqualsAndHashCodeannotationannotations from lombok as it generate getter/setter
请注意，您可能不需要来自lombok 的@Data和@EqualsAndHashCodeannotation注释，因为它会生成 getter/setter
