I have a controller which produces JSON, and from this controller, I return an entity object, which is automatically serialized by Jackson.
Now, I want to avoid returning some fields based on a parameter passed to the controller. I looked at examples where this is done using FilterProperties / Mixins etc. But all the examples I saw requires me to use ObjectMapper to serialize / de-serialize the bean manually. Is there any way to do this without manual serialization? The code I have is similar to this:
#RestController
#RequestMapping(value = "/myapi", produces = MediaType.APPLICATION_JSON_VALUE)
public class MyController {
#Autowired
private MyService myService;
#RequestMapping(value = "/test/{variable}",method=RequestMethod.GET)
public MyEntity getMyEntity(#PathVariable("variable") String variable){
return myservice.getEntity(variable);
}
}
#Service("myservice")
public class MyService {
#Autowired
private MyEntityRepository myEntityRepository;
public MyEntity getEntity(String variable){
return myEntityRepository.findOne(1L);
}
}
#Entity
#Table(name="my_table")
#JsonIgnoreProperties(ignoreUnknown = true)
public class MyEntity implements Serializable {
#Column(name="col_1")
#JsonProperty("col_1")
private String col1;
#Column(name="col_2")
#JsonProperty("col_2")
private String col2;
// getter and setters
}
Now, based on the value of "variable" passed to the controller, I want to show/hide col2 of MyEntity. And I do not want to serialize/deserialize the class manually. Is there any way to do this? Can I externally change the Mapper Jackson uses to serialize the class based on the value of "variable"?
Use JsonView in conjunction with MappingJacksonValue.
Consider following example:
class Person {
public static class Full {
}
public static class OnlyName {
}
#JsonView({OnlyName.class, Full.class})
private String name;
#JsonView(Full.class)
private int age;
// constructor, getters ...
}
and then in Spring MVC controller:
#RequestMapping("/")
MappingJacksonValue person(#RequestParam String view) {
MappingJacksonValue value = new MappingJacksonValue(new Person("John Doe", 44));
value.setSerializationView("onlyName".equals(view) ? Person.OnlyName.class : Person.Full.class);
return value;
}
Use this annotation and set the value to null, it will not be serialised:
#JsonInclude(Include.NON_NULL)
Related
I am using spring data neo4j 6.1.3 and following is my use case code snippets
Domain Entity
#Data
#Node("DATspace")
public class DatSpace {
#Id #GeneratedValue
private Long neoId;
#Property("SUPtitle")
private String title;
private String SUPid;
}
Test class
#SpringBootTest
#EnableNeo4jRepositories(basePackages = "com.rahal.marvel")
public class ProjectionTest {
#Autowired
private Neo4jTemplate neo4jTemplate;
interface DATspaceProjection {
String getTitle();
String getSUPid();
}
#Test
public void test_projection(){
DatSpace d = neo4jTemplate.findOne("MATCH (s:DATspace {SUPid: $id}) RETURN s", Collections.singletonMap("id", "SPC_ML7"), DatSpace.class).get();
d.setTitle("title modified");
d.setSUPid("SUPid modified");
DATspaceProjection p = neo4jTemplate.saveAs(d, DATspaceProjection.class);
}
}
Ideally above saveAs function should modify both DATspace.SUPtitle and DATspace.SUPid. However it only modify SUPid but not SUPtitle. I presume it is due to property mapping (#Property) . Is this a bug or are there any workaround?
The provided #Property annotation does only have an impact on the annotated property (title) itself.
There is no knowledge right now that goes from the getTitle() method in the projection to the annotated title field in the domain class.
To be safe when modifying this use the explicit property name:
interface DATspaceProjection {
String getSUPtitle();
String getSUPid();
}
I created an issue for improvement https://github.com/spring-projects/spring-data-neo4j/issues/2371
I have a controller method, that takes in a POJO.
#Data
#Builder
#NoArgsConstructor
#AllArgsConstructor
public class Dto {
private LocalDate endDate;
private String token;
private TransactionType type;
}
Transaction type is a simple enum, but I want to use a custom conversion from the inbound value to the transaction type.
#Slf4j
#Controller("/api/transactions")
public class IssuerTransactionController {
#Get(value = "/{?tr*}", produces = APPLICATION_JSON)
public List<String> get(Dto tr) {
return new ArrayList<>();
}
}
I have written a converter:
#Slf4j
#Singleton
public class TransactionTypeConverter implements TypeConverter<String, TransactionType> {
#Override
public Optional<TransactionType> convert(String value, Class<TransactionType> targetType, ConversionContext context) {
return Arrays.stream(TransactionType.values())
.filter(txnType -> StringUtils.equals(txnType.getTransactionType(), value) || StringUtils.equals(txnType.name(), value))
.findFirst();
}
}
Micronaut is not using the type converter to transform the inbound value?
Is some special registration process needed in order for Micronaut to know that it should be using the converter?
If I add a constructor to TransactionTypeConverter I can see that the class is never actually created by Micronaut at all.
If I add it as a regular dependency to the controller, it's loaded (no surprise there), but still not used. Is there a step I am missing?
Seems you are using the Binding from Multiple Query values functionality which under the hood is just creating the map of the query parameters you passed in and uses the Jackson to convert the map into your own POJO. So it does not rely on the system converters but only on the Jackson itself.
What you can do is just use Jacksons #JsonCreator annotation to customize the conversation.
Something like this should work.
public enum TransactionType {
A ("A"),
B ("B");
private final String transactionType;
TransactionType(String transactionType){
this.transactionType = transactionType;
}
public String getTransactionType() {
return transactionType;
}
#JsonCreator
public static TransactionType forValue(Collection<String> values) {
if(values == null || values.isEmpty()){
return null;
}
String value = values.get(0);
return Arrays.stream(TransactionType.values())
.filter(txnType -> StringUtils.equals(txnType.getTransactionType(), value) || StringUtils.equals(txnType.name(), value))
.findFirst().orElse(null);
}
}
Friends,
Here are my Java objects
#Data
public class CarDto {
private String make;
private String model;
private int year;
}
#Data
public class Car {
private MakeEnum make;
private String model;
private int year;
}
For consuming, I need to do something like this
#Mapper
public interface CarMapper {
CarMapper INSTANCE = Mappers.getMapper(CarMapper.class);
Car toModel(CarDto carDto);
CarDto toDto(Car carModel);
}
// Using mapper
Car carModel = CarMapper.INSTANCE.toModel(carDto);
But I am looking a solution, where I could do this:
Car carModel = Mapper.map(carDto, Car.class);
How do do this? Didn't find an example where I can dynamically map based on a Type. I found this method very handy in both ModelMapper & Google gson. Appreciate your help!
If I understand you correctly, you require a kind of repo.
Another option would be to look at sprint and the new MapStruct spring integration, recently developed: https://github.com/mapstruct/mapstruct-spring-extensions. It was designed as a follow up of this question.
There's an example in the example repo. It's not straightforward though: https://github.com/mapstruct/mapstruct-examples/tree/master/mapstruct-mapper-repo
Before calling the mapping, you have to setup and interface of MapStruct like this:
#Mapper(componentModel = "spring")
public interface MapStructMapper {
ObjectDto objectToObjectDto(Object object);
}
Then an implementation of it :
#Component
public class MapStructMapperImpl implements MapStructMapper {
#Override
public ObjectDto objectToObjectDto(Object object) {
if ( object == null ) { return null; }
ObjectDto objectDto = new ObjectDto();
objectDto.setId( object.getId() );
objectDto.setName( object.getName() );
return objectDto;
}
and then, you just have to inject this interface in the controller and invoke the repository like this:
#RequestMapping("/objects")
public class ObjectController {
private MapStructMapper mapstructMapper;
private ObjectRepository objectRepository;
#Autowired
public ObjectController(
MapStructMapper mapstructMapper,
ObjectRepository objectRepository
) {
this.mapstructMapper = mapstructMapper;
this.objectRepository = objectRepository;
}
#GetMapping("/{id}")
public ResponseEntity<ObjectDto> getById(#PathVariable(value = "id") int id){
return new ResponseEntity<>(
mapstructMapper.objectToObjectDto(
objectRepository.findById(id).get()
),
HttpStatus.OK
);
}
}
Of course, you can call a service/serviceImpl instead of a direct call to the repository but it's to be as simple as possible. :)
I'm creating DTO versions of all my entities. I have a problem with an entity that has one Enum value. This is my entity:
#Getter
#Setter
#Table(name = "TIPOS_MOVIMIENTO")
#Entity
public class TipoMovimiento {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
#Column
#Convert(converter = TipoMovEnumConverter.class)
private TipoMov tipo;
public String getTipo() {
return tipo.getTipoNombre();
}
#OneToMany(mappedBy = "tipoMov")
private List<Movimiento> movimientos;
No, I don't have #Enumerated because I followed a tutorial: "JPA 2.1 Attribute Converter – The better way to persist enums" and I had to remove it. I use a converter, as you can see.
This is my DTO of the previous entity:
#Getter
public class TipoMovimientoDto implements DtoEntity {
#Convert(converter = TipoMovEnumConverter.class) //I don't even know if write this here!!!!!
private TipoMov tipo;
}
The reason why I've followed that tutorial ↑ is because I wanted to write in database the variable values (tipoNombre) of enum (not enum name itself) because format. I want to store it in DB with accents, and I want to show it in Postman or whatever REST Client app with accents! Don't tell me anything about format it in front-end because this project is only back-end :(
Well, I think you will understand what I found with this with a image:
If you know a better way to do this, let me know, but this is not my problem now.
Let me show you the Enum:
public enum TipoMov {
INGRESO("Ingreso"),
PRESTAMO("Prestamo"),
PAGO("Pago"),
AMORTIZACION("Amortización"),
INTERES("Interés");
private String tipoNombre;
public String getTipoNombre() {
return tipoNombre;
}
TipoMov(String tipoNombre) {
this.tipoNombre = tipoNombre;
}
public static TipoMov fromDBName(String tipoNombre) {
switch (tipoNombre) {
case "Ingreso":
return TipoMov.INGRESO;
case "Préstamo":
return TipoMov.PRESTAMO;
case "Pago":
return TipoMov.PAGO;
case "Amortización":
return TipoMov.AMORTIZACION;
case "Interés":
return TipoMov.INTERES;
default:
throw new IllegalArgumentException("ShortName [" + tipoNombre
+ "] not supported.");
}
}
}
The problem is that I can't get the output in Postman if I convert this to DTO version. I get the appropiate output without DTO. I'm using REST services. Let me show you the services and controller.
(They include both versions, without DTO and with DTO (that is not working)).
ServiceImpl
#Service
public class TipoMovimientoServiceImpl implements TipoMovimientoService {
#Autowired
TipoMovimientoRepository repository;
#Autowired
DtoUtils dtoUtils;
public List<DtoEntity> findAllDto() {
List<TipoMovimiento> tiposMovimiento = repository.findAll();
List<DtoEntity> tiposMovimientoDto = new ArrayList();
for (TipoMovimiento tipoMovimiento : tiposMovimiento) {
DtoEntity tipoMovimientoDto= dtoUtils.convertToDto(tipoMovimiento, new TipoMovimientoDto());
tiposMovimientoDto.add(tipoMovimientoDto);
}
return tiposMovimientoDto;
}
public List<TipoMovimiento> findAll() {
List<TipoMovimiento> tiposMovimiento = repository.findAll();
return tiposMovimiento;
}
}
Service Interface
public interface TipoMovimientoService {
List<DtoEntity> findAllDto();
List<TipoMovimiento> findAll();
}
Controller:
#RestController
public class PruebasController {
#Autowired
TipoMovimientoService service;
#GetMapping("tiposmovdto")
public ResponseEntity <List <DtoEntity> > findAllDto() {
return ResponseEntity.ok(service.findAllDto());
}
#GetMapping("tiposmov")
public ResponseEntity <List <TipoMovimiento> > findAll() {
return ResponseEntity.ok(service.findAll());
}
}
As I said, the nonDto version works perfectly, but DTO version no. Is not the fault of DTO converter, because I have other REST services (that don't have enums) working perfectly with DTO. This is a problem about making compatible Enum and Dto!
I got it!!! I never thought this would work.
#Getter
public class TipoMovimientoDto implements DtoEntity {
private TipoMov tipo;
}
I just changed in the code above (Dto):
private TipoMov tipo;
to
private String tipo;
I can't explain how Enum from Entity could have been converted to DTO, using String instead Enum... But that worked!
In case you have the same problem... this is my Attribute Converter between Enum and String
#Converter(autoApply = true)
public class TipoMovEnumConverter implements AttributeConverter<TipoMov, String> {
public String convertToDatabaseColumn(TipoMov tipoMov) {
return tipoMov.getTipoNombre();
}
public TipoMov convertToEntityAttribute(String dbData) {
return dbData == null ? null : TipoMov.fromDBName(dbData);
}
}
Is still necessary to use it in Entity class, above of the enum variable:
#Convert(converter = TipoMovEnumConverter.class)
But not necessary in DTO. Just use String instead Enum in DTO!
I have an entity that owns another entity:
//psuedocode
public class ClassA{
private String name;
#OneToOne
private ClassB classb;
}
public class ClassB{
private String thing1;
private String thing2;
private String thing3;
}
When I retrieve ClassA objects, I don't want to see ClassB.thing3, but I do want to see thing1 and thing 2:
{
"name":"classa",
"classb":{
"thing1":"hi",
"thing2":"there"
}
}
But if I query for ClassB I want to see everything:
{"thing1":"hi",
"thing2":"there",
"thing3":"joseph"}
So I can't just put an ignore annotation over thing3, because then I'll ignore it on the second fetch. I tried a Converter<ClassB>, but that forces me to implement toString() and fromString() for the JSON, which dies on converting the JSON object to Java-side (the converter expects a String, but gets the object instead).
I want to avoid building/parsing the JSON object myself if possible to let my json provider do the work, if possible. I'm on Johnzon.
This is possible, you need to use #NamedEntityGraph,
This should help, http://www.thoughts-on-java.org/jpa-21-entity-graph-part-1-named-entity/
Something like this should be possible by querying using SELECT NEW, but you're going to need some new Classes for that ... and won't be passing your entities directly to JSON.
new Classes:
(pseudocode)
class ResultB {
String thing1;
String thing2;
public ResultB(ClassB classB) {
this.thing1 = classB.thing1;
this.thing2 = classB.thing2;
}
}
class ResultA {
String name;
ResultB resultB;
public ResultA(ClassA classA) {
this.name=classA.name;
this.resultB=new ResultB(classA);
}
}
Query:
select new ResultA(a) from ClassA a fetch join a.classB;
Then you can pass ResultA instead of ClassA to JSON.
PS: As mentioned in the comment above, I don't think NamedEntityGraphs are the way to go here
I would always fetch all the data from the database and let the filtering to be done by the JSON provider if you want to serialize it anyway. If you use Jackson you can simply add views to your fields:
public class ClassA {
#JsonView(Views.AlwaysInclude.class)
private String name;
#JsonView(Views.AlwaysInclude.class)
#OneToOne
private ClassB classb;
}
public class ClassB {
#JsonView(Views.AlwaysInclude.class)
private String thing1;
#JsonView(Views.AlwaysInclude.class)
private String thing2;
private String thing3;
}
public class Views {
public static class AlwaysInclude {
}
}
Later when you serialize your object you just need to use your view:
String result = mapper
.writerWithView(Views.AlwaysInclude.class)
.writeValueAsString(new ClassA());
When you want to serialize only ClassB then you shouldn't use views.
String result = mapper.writeValueAsString(new ClassB());