Configuration for Include Nested Objects into JSON [DATAREST-1376]

[spring-projects-issues]

asdf fsadf opened DATAREST-1376 and commented

There could be an easy way to configure if a nested object gets presented as an url-reference or as an embedded json object.

 

Example to make my suggestion clear.

 

@Entity
public class Person {

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

  @OneToOne
  private Address address;
  …
}

 

Result of a standard Repository, if an repository for address exists:

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

My suggestion is to create an annotation like this:

interface PersonRepository extends CrudRepository<Person, Long> {

    // suggested new annotation
    @Embedded(fieldNames = {"address"})
    @Override
    public Person findById(long id);
}

 To get an result like this:

{  
   "id":1,
   "firstName":"Frodo",
   "lastName":"Baggins",
   "address":{
    "id":3
    "street": "Bag End",
    "state": "The Shire",
    "country": "Middle Earth"
   }
   "_links":{  
      "self":{  
         "href":"http://localhost:8080/persons/1"
      }
   }
}

 

---

Issue Links:

• DATAREST-1377 Improve section on excerpt projections

[spring-projects-issues]

Oliver Drotbohm commented

That's in violation with the fundamental principles that underly Spring Data REST. If you have a repository for Address, you indicate that it is a separate aggregate. I.e. accessing the item resource for your Person would return two aggregates without making this obvious. This is problematic as then an update to that very same resource would have to change two different aggregates at the same time, which requires a transaction, a concept that not all backing stores that Spring Data REST can run on supports.

There already is a concept of excerpt projections that allow you to pull parts of the representation of a related resource into the _embedded clause of the representation of a resource.

Checking the reference docs, I realized that the section on (excerpt) projections deserves a bit of a polish up so that it's easier to understand the purpose of that functionality. I filed DATAREST-1377 for that

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