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.
Related
I have two classes where one class inherits the other one as given below:
public class UserData {
protected final String emailAddress;
protected final String name;
public UserData(final String emailAddress, final String name) {
this.emailAddress = emailAddress;
this.name = name;
}
public Optional<String> getEmailAddress() {
return Optional.ofNullable(this.emailAddress);
}
public Optional<String> getName() {
return Optional.ofNullable(this.name);
}
}
public class EmployeeData extends UserData {
protected final String designation;
public EmployeeData(
final String emailAddress,
final String name,
final String designation
) {
super(emailAddress, name);
this.designation = designation;
}
public Optional<String> getDesignation() {
return Optional.ofNullable(this.designation);
}
}
I need to create method in another class that can return either one of these objects and have all getters accessible. I already tried making the return type UserData for both kinds of objects (example given below) but that way, I cannot access the getDesignation getter for EmployeeData. Is there a better way inheritance can be setup to avoid this problem where I cannot access child-specific properties?
public UserData getData() {
if (...some condition) {
return new EmployeeData("address#provider.com", "myName", "Dev")
}
else {
return new UserData("address#provider.com", "myName");
}
}
I did look into these stackoverflow questions but couldn't quite figure it out for my use case
C# how to make a function that can return either child or parent class
What's the equivalent of C# IEnumerable in Java? The covariant-capable one, not the Iterable
Because the object we are returning is of type UserData, we will be unable to call methods that are added within the child class, EmployeeData. You could create the getDesignation() method inside the UserData class and have it return an empty optional object.
public Optional<String> getDesignation() {
return Optional.empty();
}
In this case, you can now override the method within the EmployeeData class to return designation as an Optional like this,
#Override
public Optional<String> getDesignation() {
return Optional.ofNullable(this.designation);
}
Now you will have access to the getDestination() method from returned object of getData(), but you will have to be careful and understand that if the returned type is of UserData, then when calling getDesignation() you will be receiving an Optional.empty() object.
I have a homework that specifies to add to an existent project a generic repository layer. The problem that i face is the following. My repository should encapsulate a map that stores the data. What I have until now is the following:
public interface IDObject<T> {
public Comparable<T> getID();
}
public class Person implements IDObject<String> {
private String cnp;
private String name;
private String age;
public Person(String cnp, String name, String age) {
this.cnp = cnp;
this.name = name;
this.age = age;
}
public void setName(String name) { this.name = name; }
public void setCNP(String cnp) { this.cnp = cnp; }
public void setAge(String age) { this.age = age; }
public String getName() { return name; }
public String getCNP() { return cnp; }
public String getAge() {return age; }
public String toString() { return cnp + "-" + name + "-" + age; }
#Override
public Comparable<String> getID() { return getCNP(); } //basically the unique identifier
}
public class Repository<T extends IDObject<?????????>>{
private IMap map;
public Repository() {
map = new Map<???????, T>();
}
...
}
So my problem appears in Repository class. I want to store persons so I will do something like Repository<Person> repo = new Repository<Person>(); But the problem is I don't know how to construct the map in the Repository constructor. In other words I don't know the type of the key. I want the Person's cnp to be the key(which is of Type String), but if I force the map to define the keys as Strings, my repository is no longer generic, because if I want to add some Animal objects that have the key as an integer , the map should be like map = new Map<Integer, T>();.
So the question is how can I still use a construction like Repository<Person> repo = new Repository<Person>(); using the fact that Objects that are stored in a repository implement IDObject and knowing that a repository encapsulates a map which stores the data? How should I get to know the key so I can complete the repository class?
You will have to introduce another generic type:
public class Repository<T, O extends IDObject<T>>
After that you can introduce StringIDRepository as
public class StringIDRepository<O extends IDObject<String>> extends Repository<String, O>
Alternative is to use Map<Object, O>, but that would require you to have in your Repository class getById method that takes Object as argument.
Hope this will help!
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.
I am trying to serialize the below ArrayList of GAccount objects using Jackson library with following code:
List<Gaccount> gAccounts;
ObjectMapper mapper=new ObjectMapper();
json=mapper.writeValueAsString(gAccounts);
However, I have noticed that only Id and Name fields are serialized but not properties. Sorry, but I am new to Jackson library. Do I have to manually serialize that field ?
package in.co.madhur.ganalyticsdashclock;
import java.util.ArrayList;
import java.util.List;
public class GAccount
{
private String Id;
private String Name;
private List<GProperty> properties=new ArrayList<GProperty>();
public GAccount(String Id, String Name)
{
this.Id=Id;
this.Name=Name;
}
public String getName()
{
return Name;
}
public void setName(String name)
{
Name = name;
}
public String getId()
{
return Id;
}
public void setId(String id)
{
Id = id;
}
List<GProperty> getProperties()
{
return properties;
}
void setProperties(List<GProperty> properties)
{
this.properties = properties;
}
#Override
public String toString()
{
return Name;
}
}
The default visibility is to use all public getter methods and all public properties. If you make the getter this:
public List<GProperty> getProperties()
it should work.
You could also change the auto-detection defaults, but it's overkill here. See http://www.cowtowncoder.com/blog/archives/2011/02/entry_443.html for more info.
I am using jackson 2.9.0. The default visibility is always 'false' to all the members. In this case, we alway need to use a different visibility, otherwise the result json string will be empty. Here is the code extracted from JsonAutoDetect
public boolean isVisible(Member m) {
switch(this) {
case ANY:
return true;
...
case PUBLIC_ONLY:
return Modifier.isPublic(m.getModifiers());
default:
return false;
}
}
What should my POJO declaration be if I want to de-serialize the following JSON format:
{
"id":2,
"content":"skfdjhsfjhsfjkshdkjfhskdjf",
"created_at":"2012-11-14T00:10:59Z",
"feeds":
[
{
"feed":{"name":"twitter"}
}
]
}
Currently my POJOs look like that:
Broadcast.java - the outtermost object
public class Broadcast {
private String content;
private String created_at;
private Feeds feed[];
private int id;
public Broadcast() { }
public int getId() { return id; }
public String getContent() { return content; }
public String getCreatedAt() { return created_at; }
}
Feed.java - the inner child of Broadcast which can be an array and each feed has a name attribute:
public class Feeds {
private String name;
public Feeds() {}
public String getName() {
return name;
}
}
private Feeds feed[];
should be
private Feeds[] feeds;.
Actually, the placement of [] doesn't matter, but it's recommended to be placed alongside the type as it makes it clearer to read. The issue here is with the incorrect variable name.
Also, if you take a closer look at:
"feeds":
[
{
"feed":{"name":"twitter"}
}
]
you'll notice that feeds is indeed an array, but "feed":{"name":"twitter"} represents a variable (feed) holding a key-value pair ({"name":"twitter"}), thus your Feeds class should look like:
class Feeds {
private Map<String, String> feed;
public Feeds() {}
public String getName() {
return feed.get("name");
}
}