Converting DynamoDB JSON to Standard JSON with Java
You can use ItemUtils class in aws sdk. Below is sample code using Kotlin:
import com.amazonaws.services.dynamodbv2.document.ItemUtils
import com.amazonaws.services.dynamodbv2.model.AttributeValue
fun main(args: Array<String>) {
val data = HashMap<String,AttributeValue>()
data.put("hello",AttributeValue().withS("world"))
println(data.toString())
println(ItemUtils.toItem(data).toJSON())
}
Output:
{hello={S: world,}}
{"hello":"world"}
Below is the complete code for converting from Dynamo JSON to Standard JSON:
import com.amazonaws.services.dynamodbv2.document.Item;
import com.amazonaws.services.dynamodbv2.document.internal.InternalUtils;
import com.amazonaws.services.dynamodbv2.model.AttributeValue;
import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.RequestHandler;
import com.amazonaws.services.lambda.runtime.events.DynamodbEvent;
import com.amazonaws.services.lambda.runtime.events.DynamodbEvent.DynamodbStreamRecord;
import com.google.gson.Gson;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
/**
* Main Lambda class to receive event stream, parse it to Survey
* and process them.
*/
public class SurveyEventProcessor implements
RequestHandler<DynamodbEvent, String> {
private static final String INSERT = "INSERT";
private static final String MODIFY = "MODIFY";
public String handleRequest(DynamodbEvent ddbEvent, Context context) {
List<Item> listOfItem = new ArrayList<>();
List<Map<String, AttributeValue>> listOfMaps = null;
for (DynamodbStreamRecord record : ddbEvent.getRecords()) {
if (INSERT.equals(record.getEventName()) || MODIFY.equals(record.getEventName())) {
listOfMaps = new ArrayList<Map<String, AttributeValue>>();
listOfMaps.add(record.getDynamodb().getNewImage());
listOfItem = InternalUtils.toItemList(listOfMaps);
}
System.out.println(listOfItem);
try {
// String json = new ObjectMapper().writeValueAsString(listOfItem.get(0));
Gson gson = new Gson();
Item item = listOfItem.get(0);
String json = gson.toJson(item.asMap());
System.out.println("JSON is ");
System.out.println(json);
}catch (Exception e){
e.printStackTrace();
}
}
return "Successfully processed " + ddbEvent.getRecords().size() + " records.";
}
}