RepositoryRestMvcConfiguration的ObjectMapper与Spring Boot默认的ObjectMapper？

Question

I'm using RepositoryRestMvcConfiguration for fine-tuning of the rest repository behaviour:

@Configuration
public class WebConfig extends RepositoryRestMvcConfiguration {
    @Override
    protected void configureRepositoryRestConfiguration(RepositoryRestConfiguration config) {
      config.setReturnBodyOnCreate(true);
}

The downside is the extended class brings in its own ObjectMapper bean, causing conficts described here . The recommended workaround is to use the extending class to mark the ObjectMapper bean as @Primary , however the bean from RepositoryRestMvcConfiguration has different behaviour while serializing nested entities.

Let's assume the following enitites:

@Entity class Parent {
    @Id Long id;
    @OneToMany @JsonManagedReference List<Child> children;
    // usual getters and setters for fields...
}

@Entity class Child {
    @Id Long id;
    @ManyToOne @JsonBackReference Parent parent;
    @ManyToOne @JsonBackReference School school;
    public getSchooldId() { return school.getId(); }
    // usual getters and setters for fields...
}

@Entity class School {
    @Id Long id;
    @OneToMany @JsonManagedReference List<Child> children;
    // usual getters and setters for fields...
} 

Using the default Spring Boot ObjectMapper gives the expected result (nested entities are rendered):

{"id": 1, "children":[{"id":2, "schoolId":7},{"id":3, "schooldId":8}]}

However the ObjectMapper from RepositoryRestMvcConfiguration ignores the child entities:

{"id": 1}

What is the correct way of configuring the RepositoryRestMvcConfiguration ObjectMapper to achieve the same behaviour as the Spring Boot default?

Answer 1

RepositoryRestMvcConfiguration creates two objectMapper objects.

1. objectMapper for internal framework use.
2. halObjectMapper responsible for rendering collection Resources and Links.

You could try to achieve the desired result by autowiring the objectMapper using a qualifier :

@Qualifier('_halObjectMapper')

EDIT: For rendering associations/nested properties

Spring data-rest does not render by default associations( reference ) because they are available under the HATEOAS Specification(the _link part of your json). If you want to render associations you just need to use Projections .

This Person has several attributes:id is the primary key, firstName and lastName are data attributes,address is a link to another domain object

@Entity
public class Person {

  @Id @GeneratedValue
  private Long id;
  private String firstName, lastName;

  @OneToOne
  private Address address;
  …
}

Will be rendered:

   {
  "firstName" : "Frodo",
  "lastName" : "Baggins",
  "_links" : {
    "self" : {
      "href" : "http://localhost:8080/persons/1"
    },
    "address" : {
      "href" : "http://localhost:8080/persons/1/address"
    }
    }
    }

By default, Spring Data REST will export this domain object including all of its attributes. firstName and lastName will be exported as the plain data objects that they are. There are two options regarding the address attribute. One option is to also define a repository for Address.

There is another route. If the Address domain object does not have it's own repository definition, Spring Data REST will inline the data fields right inside the Person resource.