Get Aggregate Information from Elasticsearch using Spring-data-elasticsearch, ElasticsearchRepository - elasticsearch

Question

I would like to get aggregate results from ES like avgSize (avg of a field with name 'size'), totalhits for documents that match a term, and some other aggregates in future, for which I don't think ElasticsearchRepository has any methods to call. I built Query and Aggregate Builders as below. I want to use my Repository interface but I am not sure of what should the return ObjectType be ? Should it be a document type in my DTOs ? Also I have seen examples where the searchQueryis passed directly to ElasticsearchTemplate but then what is the point of having Repository interface that extends ElasticsearchRepository
Repository Interface
public interface CCFilesSummaryRepository extends ElasticsearchRepository<DataReferenceSummary, UUID> {
}
Elastic configuration
#Configuration
#EnableElasticsearchRepositories(basePackages = "com.xxx.repository.es")
public class ElasticConfiguration {
#Bean
public ElasticsearchOperations elasticsearchTemplate() throws UnknownHostException {
return new ElasticsearchTemplate(elasticsearchClient());
}
#Bean
public Client elasticsearchClient() throws UnknownHostException {
Settings settings = Settings.builder().put("cluster.name", "elasticsearch").build();
TransportClient client = new PreBuiltTransportClient(settings);
client.addTransportAddress(new TransportAddress(InetAddress.getLocalHost(), 9200));
return client;
}
}
Service Method
public DataReferenceSummary createSummary(final DataSet dataSet) {
try {
QueryBuilder queryBuilder = QueryBuilders.matchQuery("type" , dataSet.getDataSetCreateRequest().getContentType());
AvgAggregationBuilder avgAggregationBuilder = AggregationBuilders.avg("avg_size").field("size");
ValueCountAggregationBuilder valueCountAggregationBuilder = AggregationBuilders.count("total_references")
.field("asset_id");
SearchQuery searchQuery = new NativeSearchQueryBuilder()
.withQuery(queryBuilder)
.addAggregation(avgAggregationBuilder)
.addAggregation(valueCountAggregationBuilder)
.build();
return ccFilesSummaryRepository.search(searchQuery).iterator().next();
} catch (Exception e){
e.printStackTrace();
}
return null;
}
DataReferernceSummary is just a POJO for now and for which I am getting an error during my build that says Unable to build Bean CCFilesSummaryRepository, illegalArgumentException DataReferernceSummary. is not a amanged Object

Answer 1

First DataReferenceSummary must be a class annotated with #Document.
In Spring Data Elasticsearch 3.2.0 (the current version) you need to define the repository return type as AggregatedPage<DataReferenceSummary>, the returned object will contain the aggregations.
From the upcoming version 4.0 on, you will have to define the return type as SearchHits<DataReferenceSummary> and find the aggregations in this returned object.