Return a shallow copy of an object in JpaRepository findAll() method

Rohan Shah :

I am trying to retrieve a list of entities using JpaRepository's findAll() method, but the Entity that I am trying to retrieve has a number of other Objects as OneToMany Relationship inside it.

I have a class Program as follows:

@Entity
public class Program extends BaseEntity {

    private String programTitle;

    private String description;

    private String programType;

    private String price;

    @OneToMany(mappedBy = "program", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.LAZY)
    @JsonManagedReference(value = "program-benefit")
    private List<Benefit> benefits = new ArrayList<>();

    @Column(name = "category")
    private String category;
    //Getters and setters
    }

As you can see, It has a list of Benefits in it.

When I am trying to retrieve Program, I am getting a JSON that has Both the objects list in it as well, Like:

Response I am getting:

{
    "id":1,
    "category": "cardio",
    "description": "exercies for cardio",
    "benefit": [
        {
            "description": "good for healt"
        },
        {
            "description": "string2"
        }
    ],
    "price": "50",
    "program_title": "cardio demo"
}

But I want a shallow copy of The object like

Expected Response:

{
    "id":1,
    "category": "cardio",
    "description": "exercies for cardio",
    "price": "50",
    "program_title": "cardio demo"
}

I tried changing CascadeType but it would stop showing nested objects in all APIs, I only want the nested objects to be removed when I call findAll() method.

Is there a way to stop showing nested objects when I call the findAll() method?

Andronicus :

I see two choices:

If you want to avoid serializing the fetched fields, use @JsonIgnore.

If you don't want to fetch those fields at all, create a DTO and write a custom query to map the results to it:

public class ProgramDTO {

    private Long id;
    private String programTitle;
    private String description;
    private String programType;
    private String price;

}

And then:

entityManager
    .createQuery("select new ProgramDTO(p.id, p.programTitle, p.description, p.programType, p.price from Program p")
    .getResultList();