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I am trying to connect to my external ElasticSearch server with Spring Boot.
If I do a curl from command line, I get expected results.
curl "http://ipAddr:9200/indexName/TYPE/_search?pretty=true"
But getting this error when I try to access it via Spring Boot.
<html><body><h1>Whitelabel Error Page</h1><p>This application has no explicit mapping for /error, so you are seeing this as a fallback.</p><div id='created'>Mon Sep 11 12:39:15 IST 2017</div><div>There was an unexpected error (type=Internal Server Error, status=500).</div><div>Could not write JSON: (was java.lang.NullPointerException); nested exception is com.fasterxml.jackson.databind.JsonMappingException: (was java.lang.NullPointerException) (through reference chain: java.util.ArrayList[0]->org.springframework.data.elasticsearch.core.aggregation.impl.AggregatedPageImpl["facets"])</div></body></html>
Not sure why a NullPointerException and what is aggregartion.impl
Here is my Spring Application:
Controller:
@RestController
public class PojoController {
@Autowired
PojoService pojoService;
@RequestMapping(value = "/", method=RequestMethod.GET)
public @ResponseBody String index() {
return new String("Welcome:)");
}
@RequestMapping(value = "/all", method = RequestMethod.GET,
produces = { MediaType.APPLICATION_JSON_VALUE })
@ResponseBody List<POJO> findAll() {
try {
List<POJO> pojoObj = pojoService.findAll();
return pojoObj;
} catch (Exception exp) {
exp.printStackTrace();
return null;
}
}
}
Repository:
@Repository
public interface PojoRepository extends ElasticsearchRepository<POJO, Integer> {
List<POJO> findAll();
}
Service:
@Service
public class POJOServiceImpl implements POJOService{
private POJORepository pojoRepository;
private ElasticsearchTemplate elasticsearchTemplate;
@Autowired
public void setPojoRepository(PojoRepository pojoRepository) {
this.pojoRepository = pojoRepository;
}
public POJO findOne(String id) {
return pojoRepository.findOne(id);
}
public List<POJO> findAll() {
return (List<POJO>) pojoRepository.findAll();
}
}
POJO class:
@Document(indexName = "INDEX", type = "TYPE")
public class POJO {
@Id
private Integer id;
private String name;
public POJO(){
// empty
}
public POJO(Integerid, String name) {
super();
this.id = id;
this.name = name;
}
// getters and setters
}
I should be able to query all the documents in the index. Later on, I will try and use filters etc.
Any help is appreciated. Thanks :)
337
It looks like Jackson has a problem with handling your POJO (probably related to this issue: DATAES-274) - the problematic part is casting in repository from Iterable collection to List.
In case of repositories, spring-data-elasticsearch behaves a bit different than you would expect. Taking your example:
@Repository
public interface PojoRepository extends ElasticsearchRepository<POJO, Integer> {
List<POJO> findAll();
}
and after calling in your rest controller:
List<POJO> pojoObj = pojoService.findAll();
in debugger you will see something like this:
You would expect that pojoObj list contains objects of POJO class.
And here comes the surprise - pojoObj ArrayList contains one object of AggregatedPageImpl type and its content field is the right list that contains your POJO objects.
This is the reason why you get:
Could not write JSON: ... java.util.ArrayList[0]->org.springframework.data.elasticsearch.core.aggregation.impl.AggregatedPageImpl[\"facets\"])
As I wrote before, Jackson cannot handle this while serializing POJO objects.
Solution 1
Let repositories return Iterable collection (by default).
@Repository
public interface PojoRepository extends ElasticsearchRepository<POJO, Integer> {
}
Move the conversion part to the service but use some utility method (here with Guava) in order to have it like this:
import com.google.common.collect.Lists;
public List<POJO> findAll() {
return Lists.newArrayList(pojoRepository.findAll());
}
Solution 2
Use Page in repository (here simplified version without parameters):
@Repository
public interface PojoRepository extends ElasticsearchRepository<POJO, Integer> {
Page<TestDto> findAll();
}
If you still want to operate on list - get content from page in service:
public List<POJO> findAll() {
return testDtoRepository.findAll().getContent();
}
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