spring rest lazy loading with hibernate - json

Question

I am trying to develop spring rest api with hibernate.
after searching in google, I have not find solution to lazy loading.
I have two entity like below:
University.java
#Entity()
#Table(schema = "core", name = "university")
public class University extends BaseEntity {
private String uniName;
private String uniTelephon;
#LazyCollection(LazyCollectionOption.FALSE)
#OneToMany(fetch = FetchType.LAZY, mappedBy = "university", cascade = CascadeType.ALL)
#JsonManagedReference
private List<Student> students;
//setter and getter
}
Student.java
#Entity
#Table(schema = "core",name = "student")
public class Student {
#Id
#GeneratedValue
private long id;
private String firstName;
private String lastName;
private String section;
#ManyToOne(fetch=FetchType.LAZY)
#JoinColumn(name = "UNIVERSITY_ID",nullable = false)
#JsonBackReference
private University university;
// setter and getter
}
any my rest end point
#GetMapping("/list")
public ResponseEntity list() throws Exception {
// I need to return just Universities But it return it eagerly with their students
return new ResponseEntity(this.universityService.findAll(), HttpStatus.OK);
}
after calling the rest api, it return university with all students.
There is a way to tell Jackson to not serialize the unfetched objects or collections?
Can somebody help me with a proved solution?

Answer 1

Try adding the following dependancy (depending on your hibernate version):
<dependency>
<groupId>com.fasterxml.jackson.datatype</groupId>
<artifactId>jackson-datatype-hibernate5</artifactId>
<version>${jackson.version}</version>
</dependency>
And then (assuming you have a Java based configuration) add the following in the WebMvcConfigurerAdapter class:
#Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
converters.add(jackson2HttpMessageConverter());
}
#Bean
public MappingJackson2HttpMessageConverter jackson2HttpMessageConverter() {
MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
converter.setObjectMapper(this.jacksonBuilder().build());
return converter;
}
public Jackson2ObjectMapperBuilder jacksonBuilder() {
Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
Hibernate5Module hibernateModule = new Hibernate5Module();
hibernateModule.configure(Feature.FORCE_LAZY_LOADING, false);
builder.modules(hibernateModule);
// Spring MVC default Objectmapper configuration
builder.featuresToDisable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
builder.featuresToDisable(MapperFeature.DEFAULT_VIEW_INCLUSION);
return builder;
}
It should force the Jackson's objectMapper to not fetch lazy-loaded values.