Document impact of pre-populated Id on `@CreatedDate` not working as expected

[ViniciusMRosa]

Hi, people

I'm trying to use Cassandra Auditing as I'm used to do while using spring-data-jpa but it isn't woking.
The field annotated with @CreatedDate is not being filled but @LastModifiedDate works normally.

To verify this behavior I used a docker image starting it with the command below

 docker run --name cassandra-local -p 9042:9042  -d cassandra:latest

Then I ran this application

package com.example.datacassandra;

import java.time.Instant;
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.annotation.CreatedDate;
import org.springframework.data.annotation.LastModifiedDate;
import org.springframework.data.cassandra.config.EnableCassandraAuditing;
import org.springframework.data.cassandra.core.mapping.Column;
import org.springframework.data.cassandra.core.mapping.PrimaryKey;
import org.springframework.data.cassandra.core.mapping.Table;
import org.springframework.data.cassandra.repository.config.EnableCassandraRepositories;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Component;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

@SpringBootApplication
@EnableCassandraAuditing
@EnableCassandraRepositories
public class DataCassandraApplication {

	public static void main(String[] args) {
		SpringApplication.run(DataCassandraApplication.class, args);
	}

}

@Table("my_table_test")
@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
class MyTest{
	@PrimaryKey
	private String key;
	@CreatedDate
	@Column("created_date")
	private Instant createdDate;
	@LastModifiedDate
	@Column("last_modified_date")
	private Instant lastModifiedDate;
}

interface MyTestRepository extends CrudRepository<MyTest,String>{}

@Component
class DataConfig implements CommandLineRunner{

	@Autowired
	private MyTestRepository repository;

	@Override
	public void run(String... args) throws Exception {
		repository.deleteAll();
		repository.save(MyTest.builder()
			.key("My Awesome key " )
		.build());
	}


}

Then I checked the database using cqlsh inside the running Cassandra container, but created date is null

cqlsh:my_test> select * from my_table_test ;

[mp911de]

Spring Data Cassandra is a bit special in regards to the IsNew detection as Cassandra cannot generate primary keys. Instead, you need to provide always an Id value. Upon save, Spring Data inspects entities and if an entity has an Id assigned, the entity is considered to be not new. You can either enable optimistic locking by adding a @Version column or implement Persistable in your entity to tell Spring Data whether the entity is new.

[ViniciusMRosa]

Thank you very much for your answer @mp911de
I used the Persistable approach and it worked like a charm.

Do you think about handling it another way or even modifying the documentation of spring-data-cassandra to add this kind of information?

[mp911de]

Updating the docs seems a good idea. We have some documentation already (see https://docs.spring.io/spring-data/jdbc/docs/current/reference/html/#is-new-state-detection) that we could reuse.