How to process "data" part of GCP PubSub message into a HashMap? - google-cloud-platform

Question

I'm getting pubsub message as below :
{
"data": {
"systemId": "system-1",
"userId": "userId-1",
"departmentId": "090",
"enrolmentDateTime": "2022-08-19T15:44:29.080Z",
"event_type": "REGISTRATION"
}
}
I want to further process this message in my springboot application based on the "event_type".
How can I just fetch "event_type" from this message and use it for comparison?
Any suggestions?
For eg I want to have processing like this :
if(event_type.equals("REGISTRATION")) { registrationHandler.handle(message); else { }
I have tried converting a PubSubMessage into string and then further map it to HashMap using ObjectMapper, but that gives me "data" as key and rest of the json part as a value.
public void process(final PubsubMessage message) throws ConsumerException {
String data = message.getData().toStringUtf8();
try {
ObjectMapper mapper = new ObjectMapper();
HashMap<String, String> dataMap = mapper.readValue(data, HashMap.class);
} ....

Answer 1

Instead of using a Map, you can use a typed object, example :
PubSubData.java file :
public class PubSubData {
private String systemId;
private String userId;
private String departmentId;
private String enrolmentDateTime;
private String event_type;
public PubSubData() {
}
public String getSystemId() {
return systemId;
}
public void setSystemId(String systemId) {
this.systemId = systemId;
}
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
public String getDepartmentId() {
return departmentId;
}
public void setDepartmentId(String departmentId) {
this.departmentId = departmentId;
}
public String getEnrolmentDateTime() {
return enrolmentDateTime;
}
public void setEnrolmentDateTime(String enrolmentDateTime) {
this.enrolmentDateTime = enrolmentDateTime;
}
public String getEvent_type() {
return event_type;
}
public void setEvent_type(String event_type) {
this.event_type = event_type;
}
}
PubSubResult.java file :
public class PubSubResult {
private PubSubData data;
public PubSubResult() {
}
public PubSubData getData() {
return data;
}
public void setData(PubSubData data) {
this.data = data;
}
}
Example of an unit test that deserializes data from PubsubMessage to the PubSubResult object :
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.google.protobuf.ByteString;
import com.google.pubsub.v1.PubsubMessage;
import org.junit.Test;
public class MyTest {
private static final ObjectMapper OBJECT_MAPPER;
static {
final ObjectMapper mapper = new ObjectMapper();
mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
mapper.configure(DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE, false);
OBJECT_MAPPER = mapper;
}
#Test
public void testDeserializePubSubData() {
final String data = "{\n" +
" \"data\": {\n" +
" \"systemId\": \"system-1\",\n" +
" \"userId\": \"userId-1\",\n" +
" \"departmentId\": \"090\",\n" +
" \"enrolmentDateTime\": \"2022-08-19T15:44:29.080Z\",\n" +
" \"event_type\": \"REGISTRATION\"\n" +
" }\n" +
"}";
final PubsubMessage message = PubsubMessage.newBuilder()
.setData(ByteString.copyFrom(data.getBytes()))
.build();
final String dataResult = message.getData().toStringUtf8();
final PubSubResult resultData = deserialize(dataResult);
// Access to the event type.
final String eventType = resultData.getData().getEvent_type();
}
private PubSubResult deserialize(final String value) {
try {
return OBJECT_MAPPER.readValue(value, PubSubResult.class);
} catch (JsonProcessingException e) {
throw new IllegalStateException("Error !!", e);
}
}
}