CandidateListServiceEC.java

/**
* Consumes a new candidate message, deserializes, and save to MongoDB
* @param candidateMessage
*/
@RabbitListener(queues = "#{candidateQueue.name}")
public void getCandidateMessage(String candidateMessage) {
  ObjectMapper objectMapper = new ObjectMapper();
  objectMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);

  TypeReference<Candidate> mapType = new TypeReference<Candidate>() {};

  Candidate candidate = null;

  try {
      candidate = objectMapper.readValue(candidateMessage, mapType);
  } catch (IOException e) {
      logger.info(String.valueOf(e));
  }

  candidateRepository.save(candidate);
  logger.debug("Candidate {} saved to MongoDB", candidate.toString());
}

/**
* Retrieves candidates from MongoDB and transforms to voter view
* @param election
* @return List of candidates
*/
public List<CandidateVoterView> getCandidatesQueueDb(String election) {
  Aggregation aggregation = Aggregation.newAggregation(
          Aggregation.match(Criteria.where("election").is(election)),
          project("firstName", "lastName", "politicalParty", "election")
                  .andExpression("concat(firstName,' ', lastName)")
                  .as("fullName"),
          sort(Sort.Direction.ASC, "lastName")
  );

  AggregationResults<CandidateVoterView> groupResults
          = mongoTemplate.aggregate(aggregation, Candidate.class, CandidateVoterView.class);

  return groupResults.getMappedResults();
}