Exclude fields from Java object using Spring

@PostMapping("/searchCarBigList")
public ResponseEntity<Cars> searchBigList(
        @Parameter(description = "some searchRequest dto") @RequestBody SearchRequest searchRequest) {

    return ResponseEntity.ok(someService.search(searchRequest));
}


@PostMapping("/searchCarSmallList")
public ResponseEntity<Cars> searchSmallList(
        @Parameter(description = "some searchRequest dto") @RequestBody SearchRequest searchRequest) {

    return ResponseEntity.ok(someService.search(searchRequest));
}




@Table(name = "CAR_TABLE")
public class Cars {

    @Id
    @Column(name = "ID")
    private Long id;

    @Column(name = "BRAND", nullable = false)
    private String brand;

    @Column(name = "COUNTRY", nullable = false)
    private String country;

    @Column(name = "CLIENT", nullable = false)
    private String client;

    @Column(name = "TRANSMISSION", nullable = false)
    private String transmission;
    
    
    Getters and Setters
}

I have two endpoint who use the same model class (Cars). For the searchBigList endpoint I would like to retrieve all car fields and for searchCarSmallList endpoint I would like to retrieve just 3 fields. I tried to do it with @JsonView annotation but it was not working for me. Anyone have better idea how to do it?

Answer

I fully agree with Tod Harter that it’s better and easier to use DTOs.

That being said, I don’t know how you’ve tried to use the @JSonView annotation. I use it in some of my DTOs. One way of getting the @JsonView annotation to work is to first create an interface. i.e.:

public interface Views {
    public static interface Simple {
    }

    public static interface Detailed extends Simple {
    }

    ...
}

Then you need to reference the views above the fields that you want to apply them to like this:

@JsonView(Views.Simple.class)
private String someField;

@JsonView(Views.Detailed.class)
private String anotherField;

...

After that you need to convert your entity object to a MappingJacksonValue like this:

...
var responseObject = new MappingJacksonValue(obj);
responseObject.setSerializationView(Views.Simple.class);
...

This is one of the ways to make the @JsonView annotations work as expected. however, it is much easier (and better) to just use DTOs and convert your entity to the appropriate response DTO you’ve created. You can make as many DTOs as you want. It’s also a good idea to use DTOs to map request bodies. That way you can easily control which fields are allowed in request bodies for i.e. POST/PUT/PATCH requests. Take a look at the ModelMapper and/or ObjectMapper classes. Those can be used to convert entities to and from DTOs.