当手动分配 ID 时，Spring Data MongoDB Annotation @CreatedDate 不起作用

本文介绍了当手动分配 ID 时，Spring Data MongoDB Annotation @CreatedDate 不起作用的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我正在尝试使用审核将 dateCreated 和 dateUpdated 保存在我的对象中，但是由于我手动设置了 ID，因此还有一些额外的工作.

I'm trying to use auditing to save dateCreated and dateUpdated in my objects, but since I set ID manually, there's some additional work.

遵循 Oliver Gierke 在 DATAMONGO-946 中的建议我正在尝试弄清楚如何正确实现它.

Following Oliver Gierke's suggestion in DATAMONGO-946 I'm trying to figure out how to correctly implement it.

作为上述 Jira 任务中的原始海报，我已从此处下载示例 github/spring-guides/gs-accessing-data-mongodb.git 并稍作修改:

As original poster in Jira task above, I've downloaded example from here github/spring-guides/gs-accessing-data-mongodb.git and modified it a bit:

package hello; import org.springframework.data.annotation.CreatedDate; import org.springframework.data.annotation.Id; import org.springframework.data.annotation.LastModifiedDate; import org.springframework.data.domain.Persistable; import java.util.Date; public class Customer implements Persistable<String> { @Id private String id; @CreatedDate private Date createdDate; @LastModifiedDate private Date lastModifiedDate; private String firstName; private String lastName; private boolean persisted; public Customer() { } public Customer(String firstName, String lastName) { this.firstName = firstName; this.lastName = lastName; } public void setPersisted(boolean persisted) { this.persisted = persisted; } @Override public String getId() { return id; } public void setId(String id) { this.id = id; } @Override public boolean isNew() { return !persisted; } @Override public String toString() { return String.format( "Customer[id=%s, createdDate=%s, lastModifiedDate=%s, firstName='%s', lastName='%s']", id, createdDate, lastModifiedDate, firstName, lastName); } }

和

package hello; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.CommandLineRunner; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.data.mongodb.config.EnableMongoAuditing; @SpringBootApplication @EnableMongoAuditing public class Application implements CommandLineRunner { @Autowired private CustomerRepository repository; public static void main(String[] args) { SpringApplication.run(Application.class, args); } @Override public void run(String... args) throws Exception { repository.deleteAll(); // create a customer Customer c = new Customer("Alice", "Smith"); c.setId("test_id"); // save a customer repository.save(c); // fetch all customers System.out.println("Customers found with findAll():"); System.out.println("-------------------------------"); for (Customer customer : repository.findAll()) { System.out.println(customer); } System.out.println(); // create another customer with same id c = new Customer("Bob", "Smith"); c.setId("test_id"); c.setPersisted(true); repository.save(c); // fetch all customers System.out.println("Customers found with findAll():"); System.out.println("-------------------------------"); for (Customer customer : repository.findAll()) { System.out.println(customer); } System.out.println(); } }

执行的结果是这样的:

Customers found with findAll(): ------------------------------- Customer[id=test_id, createdDate=Wed Feb 24 00:43:47 WITA 2016, lastModifiedDate=Wed Feb 24 00:43:47 WITA 2016, firstName='Alice', lastName='Smith'] Customers found with findAll(): ------------------------------- Customer[id=test_id, createdDate=null, lastModifiedDate=Wed Feb 24 00:43:47 WITA 2016, firstName='Bob', lastName='Smith']

createdDate 对象更新后变为null.

我在这里缺少什么?以及如何正确实现Persistable，让审计正常工作?

What am I missing here? And how to correctly implement Persistable to make auditing work properly?

推荐答案

您的代码按预期工作.实现 Persistable 后，您可以看到 @CreatedDate 注释正在工作.

Your code is working as expected. After you've implemented Persistable you can see that @CreatedDate annotation is working.

确保 createdDate 在第二次调用 save 时为 null，因为该对象已存在于数据库中并且您使用 createdDate = null.正如您从 @CreatedDate 的文档中看到的:

Sure that createdDate is null on the second call of save because the object already exists in the database and you updated it with createdDate = null. As you can see from the documentation for @CreatedDate:

@CreatedDate 注释.这标识了其值被设置的字段当实体第一次持久化到数据库时.

@CreatedDate annotation. This identifies the field whose value is set when the entity is persisted to the database for the first time.

所以不要在第二次调用时用 null 覆盖您的 createdDate，您应该使用 c = repository.findOne("test_id" 从数据库中检索您的客户); 然后更新它.

So not to overwrite your createdDate with null on the second call you should retrieve your customer from the database with c = repository.findOne("test_id"); and then update it.