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convert a DTO to Entity with using mapper class

I have a Entity class something like this:
#Entity
public class Website {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
private String name;
private String url;
public Website() {
//Constructor
//getters and setters
}
here is the DTO class:
public class WebsiteDto {
private Integer id;
private String name;
private String url;
public WebsiteVo() {
//Constructor
//getters and setters
}
I have the WebsiteMapper something like this:
#Component
public class WebsiteMapper {
public List<WebsiteDto> getWebsiteList() {
return repository.findAll().stream().map(w -> {
WebsiteDto dto = new WebsiteVo(w.getId(), w.getName(), w.getUrl());
return dto;
}).collect(Collectors.toList());
I also have Repository Interface:
public interface WebsiteRepository extends JpaRepository<Website, Integer> {
}
I want now to convert DTO to entity using my class WebsiteMapper. Because I did the conversion in this class. How I can do it?

How about using BeanUtils provided by spring org.springframework.beans.BeanUtils, something like this
public List<WebsiteDto> getWebsiteList() {
return repository.findAll().stream().map(w -> {
WebsiteDto dto = new WebsiteVo();
BeanUtils.copyProperties(w, dto); // copys all variables with same name and type
return dto;
})
.collect(Collectors.toList());
}

Hi I guess you wish to converting your entity to DTO. It's quite simple. Create static methods in your DTO class or any util class. The return type should be your DTO type.
e.g.
public class WebsiteDto {
private Integer id;
private String name;
private String url;
public static WebsiteDto export(Website website) {
// Return a new instance of your website DTO
return new WebsiteDto(
website.getId(),
website.getName(),
website.getUrl()
);
}
public static List<WebsiteDto> export(List<Website> websites) {
// Return a new instance of your website DTO list
return websites.stream().map(website -> {
return new WebsiteDto(
website.getName(),
website.getUrl()
}).collect(Collectors.toList());
}
}
NOTE You can also convert your DTO to entity using similar method.

jackson serialization of nested objects

I have problem with jackson serialization of object by its interface.
I have class
class Point implements PointView {
private String id;
private String name;
public Point() {
}
public Point(String id, String name) {
this.id = id;
this.name = name;
}
#Override
public String getId() {
return id;
}
public String getName() {
return name;
}
}
which implements
interface PointView {
String getId();
}
and have class
class Map implements MapView {
private String id;
private String name;
private Point point;
public Map() {
}
public Map(String id, String name, Point point) {
this.id = id;
this.name = name;
this.point = point;
}
#Override
public String getId() {
return id;
}
public String getName() {
return name;
}
#JsonSerialize(as = PointView.class)
public Point getPoint() {
return point;
}
}
which implements
interface MapView {
String getId();
Point getPoint();
}
And have class
class Container {
private Map map;
public Container() {
}
public Container(Map map) {
this.map = map;
}
#JsonSerialize(as = MapView.class)
public Map getMap() {
return map;
}
}
I want serialize Container with Jackson and get result
{"map":{"id":"mapId","point":{"id":"pointId"}}}
But in fact I get result
{"map":{"id":"mapId","point":{"id":"pointId","name":"pointName"}}}
that have property "name" in nested object "point" although I specified serializition type of Point in Map (#JsonSerialize(as = PointView.class)). Interface PointView dont have method getName, but in result exists field "name" of Point.
If I remove annotation (#JsonSerialize(as = MapView.class)) from method getMap in class Container I get result
{"map":{"id":"mapId","name":"mapName","point":{"id":"pointId"}}}
Now point dont have property "name", but map have.
How can I get result
{"map":{"id":"mapId","point":{"id":"pointId"}}}
?

To get the desired result also the same method in interface must be annotated by #JsonSerialize
interface MapView {
String getId();
#JsonSerialize(as = PointView.class)
Point getPoint();
}

You can annotate the method like this:
#JsonIgnore
public String getName() {
return name;
}
Or if you want specific serialization in this use case, but normal serialization in others, you can use a #JsonView (see doc).
The reason it's serializing out the name is that the instance has the accessor getName(), even though interface does not.

Yes, you can use
#JsonSerialize(as=MyInterface.class)
public class ConcreteClass implements MyInterface { .... }
either on implementation class (as above), or on property that has value.

jackson object property into primitive

I have the follow json.
{
foo:{
id:1
},
name:'Albert',
age: 32
}
How can I deserialize to Java Pojo
public class User {
private int fooId;
private String name;
private int age;
}

This is what you need to deserialize, using the JsonProperty annotations in your constructor.
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.IOException;
public class User {
private int fooId;
private String name;
private int age;
public int getFooId() {
return fooId;
}
public String getName() {
return name;
}
public int getAge() {
return age;
}
public User(#JsonProperty("age") Integer age, #JsonProperty("name") String name,
#JsonProperty("foo") JsonNode foo) {
this.age = age;
this.name = name;
this.fooId = foo.path("id").asInt();
}
public static void main(String[] args) {
ObjectMapper objectMapper = new ObjectMapper();
String json = "{\"foo\":{\"id\":1}, \"name\":\"Albert\", \"age\": 32}" ;
try {
User user = objectMapper.readValue(json, User.class);
System.out.print("User fooId: " + user.getFooId());
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output:
User fooId: 1
Hope it helps,
Jose Luis

You can do one of the following:
Create a concrete type representing Foo:
public class Foo {
private int id;
...
}
Then in User you would have:
public class User {
private Foo foo;
...
}
Use a Map<String, Integer>:
public class User {
private Map<String, Integer> foo;
...
}
If other callers are really expecting you to have a getFooId and a setFooId, you can still provide these methods and then either delegate to Foo or the Map depending on the option you choose. Just make sure that you annotate these with #JsonIgnore since they aren't real properties.

You can use a very helpful gson google API.
First of all, create these two classes:
User class:
public class User{
Foo foo;
String name;
int age;
//getters and setters
}
Foo class:
public class Foo{
int id;
//getters and setters
}
If you have a example.json file then deserialize it as follow
Gson gson = new Gson();
User data = gson.fromJson(new BufferedReader(new FileReader(
"example.json")), new TypeToken<User>() {
}.getType());
If you have a exampleJson String then deserialize it as follow
Gson gson = new Gson();
User data = gson.fromJson(exampleJson, User.class);

Deserializing JSON wrapper object with list returns null properties

I got json like below:
{"examinationTypes":[{"ExaminationTypeVO":{"id":1,"name":"Badanie krwi"}},{"ExaminationTypeVO":{"id":2,"name":"Spirometria"}},{"ExaminationTypeVO":{"id":3,"name":"Wymaz"}},{"ExaminationTypeVO":{"id":4,"name":"Ciśnienie"}},{"ExaminationTypeVO":{"id":5,"name":"EKG"}},{"ExaminationTypeVO":{"id":6,"name":"Elektrowstrząsy"}},{"ExaminationTypeVO":{"id":7,"name":"Tomografia"}},{"ExaminationTypeVO":{"id":8,"name":"Lewatywa"}},{"ExaminationTypeVO":{"id":9,"name":"Aneskopia"}},{"ExaminationTypeVO":{"id":10,"name":"Rektoskopia"}},{"ExaminationTypeVO":{"id":11,"name":"Kolonoskopioa"}},{"ExaminationTypeVO":{"id":12,"name":"Echo serca"}},{"ExaminationTypeVO":{"id":13,"name":"Ablacja"}},{"ExaminationTypeVO":{"id":14,"name":"Badnaie dopplerowskie"}},{"ExaminationTypeVO":{"id":15,"name":"Kapilaroskopia"}}]}
I have defined types:
#JsonRootName(value="ExaminationTypeVO")
#JsonIgnoreProperties(ignoreUnknown = true)
public class ExaminationTypeVO {
private Long id;
private String name;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
and
public class ExaminationTypesVO {
private List<ExaminationTypeVO> examinationTypes;
public List<ExaminationTypeVO> getExaminationTypes() {
return examinationTypes;
}
public void setExaminationTypes(List<ExaminationTypeVO> examinationTypes) {
this.examinationTypes = examinationTypes;
}
When I am deserializing it like that:
ExaminationTypesVO l = m.readValue(result, ExaminationTypesVO.class);
I receive an wrapper object but the list inside contains objects of type ExaminationTypeVO with all properties set to null.
Can anybody help to figure it out?

Your issue is that you have an extra level of object that you are trying to deserialize. Trying to not be confusing as I explain this: you have an array of objects, those objects contain a single ExaminationTypeVO object.
If you are stuck with the structure of the JSON that you provided, then you will need to add another "level" to your deserialization. You can do this via a wrapper object inside of your ExaminationTypesVO class:
public class ExaminationTypesVO {
private List<ExaminationTypeVOWrapper> examinationTypes;
public List<ExaminationTypeVOWrapper> getExaminationTypes() {
return examinationTypes;
}
public void setExaminationTypes(List<ExaminationTypeVOWrapper> examinationTypes) {
this.examinationTypes = examinationTypes;
}
public static class ExaminationTypeVOWrapper {
private final ExaminationTypeVO examinationTypeVO;
#JsonCreator
public ExaminationTypeVOWrapper(#JsonProperty("ExaminationTypeVO") ExaminationTypeVO examinationTypeVO) {
this.examinationTypeVO = examinationTypeVO;
}
public ExaminationTypeVO getExaminationTypeVO() {
return examinationTypeVO;
}
}
}
If you have control over the JSON that you are deserializing, you can just remove the extra "level" (ExaminationTypeVO wrapping object) and not have to change your code. Your new JSON in this approach would look like:
{
"examinationTypes": [
{
"id": 1,
"name": "Badanie krwi"
}, ...
]
}
With either of these approaches you can remove both of the class-level annotations you have on ExaminationTypeVO.

How to deserialize JSON Array contained an abstract class without modifying a parent class?

I'm trying to deserialize JSON Array, which is persisted into my MongoDB, to a Java object by using Jackson. I found many tutorials mentioned to handle this polymorphism by adding:
#JsonTypeInfo(use=Id.CLASS,property="_class")
to a Super-class. However, in my case, I can't be able to modify the Super-class. So, are there some solutions to solve it without modifying the Super-class? Here is my code:
public class User {
#JsonProperty("_id")
private String id;
private List<Identity> identities; // <-- My List contains objects of an abstract class; Identity
public User(){
identities = new ArrayList<Identity>();
}
public static Iterable<User> findAllUsers(){
return users().find().as(User.class); // Always give me the errors
}
/*More code*/
}
It always give me the error - Can not construct instance of securesocial.core.Identity, problem: abstract types either need to be mapped to concrete types, have custom deserializer, or be instantiated with additional type information.

You can use #JsonDeserilize annotation to bind a concrete implementation class to an abstract class. If you cannot modify your abstract class you can use the Jackson Mix-in annotations to tell Jackson how to find the implementation class.
Here is an example:
public class JacksonAbstract {
public static class User {
private final String id;
private final List<Identity> identities;
#JsonCreator
public User(#JsonProperty("_id") String id, #JsonProperty("identities") List<Identity> identities) {
this.id = id;
this.identities = identities;
}
#JsonProperty("_id")
public String getId() {
return id;
}
public List<Identity> getIdentities() {
return identities;
}
}
public static abstract class Identity {
public abstract String getField();
}
#JsonDeserialize(as = IdentityImpl.class)
public static abstract class IdentityMixIn {
}
public static class IdentityImpl extends Identity {
private final String field;
public IdentityImpl(#JsonProperty("field") String field) {
this.field = field;
}
#Override
public String getField() {
return field;
}
}
public static void main(String[] args) throws IOException {
User u = new User("myId", Collections.<Identity>singletonList(new IdentityImpl("myField")));
ObjectMapper mapper = new ObjectMapper();
mapper.addMixInAnnotations(Identity.class, IdentityMixIn.class);
String json = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(u);
System.out.println(json);
System.out.println(mapper.readValue(json, User.class));
}
}