In a previous post we used DynamoDBMapper in order to map DynamoDB Tables into Java objects.

When it comes to insert, our actions are pretty much the same but with a more convenient way. In order to insert an item all you have to do is to persist an object using the object mapper

In our case, we will create a User repository that does a simple insert.

package com.gkatzioura.dynamodb.mapper.repository;

import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper;
import com.gkatzioura.dynamodb.mapper.entities.User;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**
 * Created by gkatzioura on 9/22/16.
 */
public class UserMapperRepository {

 private DynamoDBMapper dynamoDBMapper;

 public UserMapperRepository(AmazonDynamoDB amazonDynamoDB) {
 dynamoDBMapper = new DynamoDBMapper(amazonDynamoDB);
 }

 public void insert(User user) {

 dynamoDBMapper.save(user);
 }

}

To persist we just have to create a simple object.

@Test
 public void testInsertUser() {

 User user = new User();
 user.setRegisterDate(new Date().getTime());
 user.setFullName("John Doe");
 user.setEmail("john@doe.com");

 userMapperRepository.insert(user);
 }

Also using DynamoDBMapper we can do batch inserts or batch deletes. Therefore we will add two extra methods to the repository.

public void insert(List<User> users) {

 dynamoDBMapper.batchWrite(users,new ArrayList<>());
 }

 public void delete(List<User> users) {
 dynamoDBMapper.batchDelete(users);
 }

Adding items in batch (or deleting) them, simply requires to pass a list of objects that contains values for the keys defined.

@Test
 public void testBatchUserInsert() {

 List<User> users = new ArrayList<>();

 for(int i=0;i<10;i++) {

 String email = emailPrefix+i+"@doe.com";
 User user = new User();
 user.setRegisterDate(new Date().getTime());
 user.setFullName("John Doe");
 user.setEmail("john@doe.com");
 users.add(user);
 }

 userMapperRepository.insert(users);
 }

 @Test
 public void testBatchDelete() {

 testBatchUserInsert();

 List<User> users = new ArrayList<>();

 for(int i=0;i<10;i++) {

 String email = emailPrefix+i+"@doe.com";
 User user = new User();
 user.setRegisterDate(new Date().getTime());
 user.setFullName("John Doe");
 user.setEmail("john@doe.com");
 users.add(user);
 }
 
 userMapperRepository.delete(users);
 }

You can find the sourcecode on github