Lazy collection in Spring JPA with Jackson and elasticsearch wihtout jsonignore - json

Question

We have spring boot with elasticsearch and mysql. We have a feature for reindexing all data from the mysql into elasticsearch, which is simple as:
#Service
#Transactional
public class SearchIndexer {
public void reindex(){
elasticsearchRepository.save(jpaRepository.findAll());
}
}
Now we have an entity called invoice, which has a lazy loaded collection with a "derived" calculation:
#Entity
#Table(name = "invoice")
#Document(indexName = "invoice")
public class Invoice implements Serializable {
//... other props
#OneToMany(fetch = FetchType.LAZY, mappedBy = "invoice")
#JsonIgnore
private Set<InvoiceItem> invoiceItems = new LinkedHashSet<>();
// getter and setters for invoiceItems
public boolean isAllSimple() {
if(getInvoiceType()==null){
return false;
}
if(getInvoiceItems()==null){
return false;
}
for(InvoiceItem item : getInvoiceItems()){
if(!item.isSimple()){
return false;
}
}
return true;
}
}
When the rest-controller is used, the resulting json contains correctly a property "allSimple". This is, because we run that with hibernate5module in one transaction.
However, when we call elasticsearchRepository.save(jpaRepository.findAll()) (also in a transaction), the objectmapper for elasticsearch cannot serialize the "allSimple" property, beacause of a LazyInitializationException. The elasticsearch-objectmapper is configured as follows:
#Bean
public ElasticsearchTemplate elasticsearchTemplate(Client client, Jackson2ObjectMapperBuilder jackson2ObjectMapperBuilder, Hibernate5Module hibernate5Module) {
return new ElasticsearchTemplate(client, new CustomEntityMapper(jackson2ObjectMapperBuilder.createXmlMapper(false).modulesToInstall(hibernate5Module).build()));
}
public class CustomEntityMapper implements EntityMapper {
private ObjectMapper objectMapper;
public CustomEntityMapper(ObjectMapper objectMapper) {
this.objectMapper = objectMapper;
objectMapper.configure( DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
objectMapper.configure( DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY, true);
}
#Override
public String mapToString(Object object) throws IOException {
return objectMapper.writeValueAsString(object);
}
#Override
public <T> T mapToObject(String source, Class<T> clazz) throws IOException {
return objectMapper.readValue(source, clazz);
}
}
The hibernate5module is loaded and registered, but did not solve the problem.
Normally we would add a "JsonIgnore" to that property, but we need that value, so this is no option.
Any ideas?!

Answer 1

I had a project configurated with this.
#EnableWebMvc
#Configuration
#ComponentScan(basePackages = "com.sagasoftware.tracker.*")
public class WebConfiguration extends WebMvcConfigurerAdapter {
#Bean
public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() {
MappingJackson2HttpMessageConverter messageConverter = new MappingJackson2HttpMessageConverter();
ObjectMapper objectMapper = new ObjectMapper();
Hibernate5Module hibernate5Module = new Hibernate5Module();
objectMapper.registerModule(hibernate5Module);
objectMapper.configure(FAIL_ON_UNKNOWN_PROPERTIES, false);
objectMapper.setSerializationInclusion(JsonInclude.Include.NON_EMPTY);
messageConverter.setObjectMapper(objectMapper);
return messageConverter;
}
#Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
converters.add(mappingJackson2HttpMessageConverter());
super.configureMessageConverters(converters);
}
}
If you are using spring boot, declaring the bean MappingJackson2HttpMessageConverter and registering the hibernate5module should fix your problem.
I could render a entity throught a rest controller.