Spring Boot Data REST #JsonValue POJO serializes as POJO with content field - java

I am using spring boot 1.5.1.RELEASE, with jackson as MessageConverter.
One of my POJO is looking something like following:
#Getter
#AllArgsConstructor
public class Pojo1 {
#Id
private final String id;
private final NestedValue payload;
}
public class NestedValue {
private final String value;
public NestedValue(String value) {
this.value = value;
}
#JsonCreator
public static NestedValue(String value) {
return new NestedValue(value);
}
#JsonValue
public String getValue() {
return value;
}
}
#RepositoryRestResource(collectionResourceRel = 'pojos', path='pojos')
public interface Pojo1Repository extends MongoRepository<Pojo, String> {
}
I am expecting above to be serialized as this:
{
"payload": "value projected by getValue()"
}
Instead, I am getting as below:
{
"payload": {
"content": "value projected by getValue()"
}
}
If I test it with default ObjectMapper, POJO is serialized as I expected.
Is there a hidden jackson feature that is configured by Spring???

Related

How to change JSON representation for single value java object?

I had a class like:
public class EmailAddress {
public String value;
public String tld() {...}
public String host() {...}
public String mailbox() {...}
}
Now I use this class in an Object / Entity:
#Entity
public class Customer {
public String name;
public EmailAddress mail;
}
Now, when I do a rest service for Customer, I get this format:
{
"id": 1,
"name": "Test",
"email": {
"value": "test#test.de"
}
}
But I only want "email": "test#test.de"
{
"id": 1,
"name": "Test",
"email": "test#test.de"
}
What I must do? I use Spring Boot and Hibernate Entities.
Thank you for any support
You should use DTO class in request handling and make mappings from DTO to Entity and backwards, e.g.:
public class CustomerDTO {
private Integer id;
private String name;
private String email;
}
You should use DataTransferObjects for your (REST) APIs.
The DTOs only contain the fields the interface should provide (or receive).
When receiving objects from the client and before returning the object from your Controller you can convert the DTOs to your domain model (Which could be your JPA entites classes).
Example for a controller method. We assume you get an object from an user-editor which contains all data you want to update in your database-objects and return the updated company DTO:
#PutMapping
public CustomerDto updateCustomer(CustomerEditorDto updatedCustomerDto) {
Customer updatedCustomer = CustomerConverter.convert(updatedCustomerDto);
updatedCustomer = customerService.updateCustomer(updatedCustomer);
return CustomerConverter.convert(updatedCustomer);
}
and your Converter class:
#NoArgsConstructor(access = AccessLevel.PRIVATE)
public class CustomerConverter {
public static CustomerDto convert(Customer customer) {
CustomerDto result = null;
if (customer != null) {
// TODO: set fields in result-dto
}
return result;
}
public static Customer convert(CustomerEditorDto customer) {
Customer result = null;
if (customer != null) {
// TODO set fields in result;
}
return result;
}
}
and here are the DTOs
#Getter
#Setter
public class CustomerDto {
private Integer id;
private String name;
private String email;
}
#Getter
#Setter
public class CustomerEditorDto {
private Integer id;
private String firstName;
private String lastName;
private String email;
private String otherPropertyOrStuff;
}
This way you can separate the API modell from your JPA entites. You can use the same models for input/output. And you can even use a different model to work with inside your services and the finally convert them into your JPA entites, before persisting the data (or after reading the data).
There are tools which can take care of the conversion, like mapstruct.
* The above annotations #Getter, #Setter, ... are from project lombok and very are handy to generate boiler-plate code automatically.
I found an other easier solution, use a JsonSerializer on the entity Property:
#JsonSerialize(using = EmailAddressSerializer.class)
private EmailAddress email;
The serializer class:
public class EmailAddressSerializer extends StdSerializer<EmailAddress> {
public EmailAddressSerializer() {
super(EmailAddress.class);
}
protected EmailAddressSerializer(Class<EmailAddress> t) {
super(t);
}
#Override
public void serialize(EmailAddress email,
JsonGenerator jsonGenerator,
SerializerProvider serializerProvider) throws IOException {
jsonGenerator.writeString(email.value);
}
}

Lombok with JsonDeserializer

I have a JSON string that I want to deserialize into a class. The JSON looks like so:
{ "data": { "name": "Box 1", "size": "10x20" } }
I can deserialize this into the following class:
#Builder
#Value
#JsonDeserialize(builder = Box1.Box1Builder.class)
public class Box1 {
#JsonProperty("data")
Box1Data data;
public static Box1 of(String json) throws IOException {
return new ObjectMapper().readValue(json, Box1.class);
}
#Builder
#Value
#JsonDeserialize(builder = Box1Data.Box1DataBuilder.class)
static class Box1Data {
#JsonProperty("name")
String name;
#JsonProperty("size")
String size;
}
}
The above class looks clumsy since it has a useless hierarchy of data. I can get rid of it like so:
#Builder
#Value
#JsonDeserialize(using = Box2Deserializer.class)
public class Box2 {
#JsonProperty("name")
String name;
#JsonProperty("size")
String size;
public static Box2 of(String json) throws IOException {
return new ObjectMapper().readValue(json, Box2.class);
}
static class Box2Deserializer extends JsonDeserializer<Box2> {
#Override
public Box2 deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException, JsonProcessingException {
var node = jsonParser.getCodec().readTree(jsonParser);
var dataNode = node.get("data");
return Box2.builder()
.name(dataNode.get("name").toString())
.size(dataNode.get("size").toString())
.build();
}
}
}
But here, I hit a dead-end. I want the size field to be parsed into a Dimension instance. I can write a custom deserializer for size that parses a String and returns a proper Dimension, but I cannot use it via field annotations (#JsonDeserialize(using = SizeDeserializer.class) since the presence of JsonDeserialize class annotation forces it to be ignored in the case for Box1, and in the case for Box2, it's ignored cuz I'm building the box manually.
Is there an elegant solution to all this mess? What I want is to read the given JSON into a class like this:
#Builder
#Value
public class Box3 {
#JsonProperty("name")
String name;
#JsonProperty("size")
Dimension size;
public static Box3 of(String json) {
...
}
}
Thanks!
Asim
I will add to #Iprakashv solution, besides only the needs for the JsonRootName type annotation and mapper serialization / deserialization for root node wrapping, you only need a custom type converter from a raw type to your custom type:
#Builder
#Value
#JsonRootName("data")
public class Box {
#JsonProperty("name")
String name;
#JsonDeserialize(converter = StringToDimensionConverter.class)
#JsonProperty("size")
Dimension size;
public static Box of(String json) throws IOException {
ObjectMapper mapper = new ObjectMapper();
mapper.enable(DeserializationFeature.UNWRAP_ROOT_VALUE);
mapper.enable(SerializationFeature.WRAP_ROOT_VALUE);
return mapper.readValue(json, Box.class);
}
private static class StringToDimensionConverter extends StdConverter<String, Dimension> {
#Override
public DataWrapper.Box1Data.Dimension convert(String s) {
return new DataWrapper.Box1Data.Dimension(s);
}
}
}
You actually do not need a custom deserializer and the #JsonDeserialize annotation. The ObjectMapper provides a configuration to enable wrapping/unwrapping a root value which can be provided using the #JsonRootName annotation over the Wrapper object class.
#Builder
#Value
#JsonRootName("data")
public class Box {
#JsonProperty("name")
String name;
#JsonProperty("size")
String size;
public static Box of(String json) throws IOException {
ObjectMapper mapper = new ObjectMapper();
mapper.enable(DeserializationFeature.UNWRAP_ROOT_VALUE);
return mapper.readValue(json, Box.class);
}
}
PS: Totally missed the Dimension part in the question, for that, you can use a custom deserializer as mentioned in other answer.

Creating complex JSON payload from Java Pojo Jackson

I want to create below JSON payload
{
"maxResults":3,
"counter":0,
"customerParameters":{
"filters":[
{
"name":"customerId",
"operator":"=",
"value":["hello"]
}
]
},
"dealerParameters":[
{
"name":"club"
},
{
"name":"token"
}
]
}
Coded so far:
#JsonInclude(JsonInclude.Include.NON_NULL)
#JsonPropertyOrder({
"maxResults",
"counter",
"customerParameters",
"dealerParameters"
})
public class CustomerModel {
#JsonProperty("maxResults")
private Integer maxResults;
#JsonProperty("counter")
private Integer counter;
#JsonProperty("customerParameters")
private CustomerParameters customerParameters;
#JsonProperty("dealerParameters")
private List<DealerParameter> dealerParameters = null;
#JsonProperty("customerParameters")
public CustomerParameters getCustomerParameters() {
return customerParameters;
}
#JsonProperty("customerParameters")
public void setCustomerParameters(CustomerParameters customerParameters) {
this.customerParameters = customerParameters;
}
#JsonProperty("dealerParameters")
public List<DealerParameter> getDealerParameters() {
return dealerParameters;
}
#JsonProperty("dealerParameters")
public void setDealerParameters(List<DealerParameter> dealerParameters) {
this.dealerParameters = dealerParameters;
}
// Getter/Setter for other params
}
CustomerParameters.java
#JsonInclude(JsonInclude.Include.NON_NULL)
#JsonPropertyOrder({
"filters"
})
public class CustomerParameters {
#JsonProperty("filters")
private List<Filter> filters = null;
// Setter and Getter for filters parameter
}
DealerParameters.java
#JsonInclude(JsonInclude.Include.NON_NULL)
#JsonPropertyOrder({
"name"
})
public class DealerParameter {
#JsonProperty("name")
private String name;
#JsonProperty("name")
public String getName() {
return name;
}
#JsonProperty("name")
public void setName(String name) {
this.name = name;
}
}
Filter.java
#JsonInclude(JsonInclude.Include.NON_NULL)
#JsonPropertyOrder({
"name",
"operator",
"value"
})
public class Filter {
#JsonProperty("name")
private String name;
#JsonProperty("operator")
private String operator;
#JsonProperty("value")
private List<String> value = null;
#JsonProperty("value")
public List<String> getValue() {
return value;
}
#JsonProperty("value")
public void setValue(List<String> value) {
this.value = value;
}
// Setter and Getter for other properties
}
Missing Part:
#Controller
public class TestContoller {
RestTemplate restTemplate;
Should I instantiate each pojo class with new operator as below and set all required parameters ? or any other approach of creating JSON payload?
CustomerModel customerModel= new CustomerModel();
customerModel.setMaxResults(1);
Filter filter= new Filter();
filter.setName("customerID");
filter.setOperator("-");
filter.setValue(Arrays.asList("club"));
CustomerParameters customerParameters = new CustomerParameters();
customerParameters.setFilters(Arrays.asList(filter));
customerModel.setCustomerParameters(customerParameters);
For DealerParameter class, I want to create multiple objects with same key different value(see the json payload I mentioned above). Below code creates only one object "name":"dealerId"
DealerParameter dealerParameter = new DealerParameter();
dealerParameter.setName("dealerId");
customerModel.setDealerParameters(dealerParameter);
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.writeValueAsString(customerModel);
restTemplate.exchange(todo); // restful service call
}
you are already using "ObjectMapper", And ObjectMapper has readValue() method. By using readValue() method you can populate all data at a time like below:--
ObjectMapper objectMapper = new ObjectMapper();
//populating data from json string to POJO
CustomerModel customerModel = objectMapper.readValue(<json String>,CustomerModel.class);
System.out.println(objectMapper.writeValueAsString(customerModel); // print all data

Generic POJO for JSON Object that can take different type of values

I have a json payload (request payload of a rest api) with a defined schema, but there is one property that can take an array of unknown key value pairs. The value for each property can be of different type like number, string, array, range, date, etc. How do i create a POJO for this property and make deserialization work for the same?
I am currently thinking about writing a custom deserializer for my Property class, where i check the type of value and do some custom logic accordingly.
This looks like a typical requirement. I feel that there should be something available in Jackson or Gson that i am missing. I would love to reuse if it already exist. I looked around in SO, but couldnt find a good answer so far. Any suggestions would be appreciated.
{
"id": 1234,
"name": "test name 1",
"properties": [
{
"key_a": 100
},
{
"key_b": [
"string1",
"string2",
"string3"
]
},
{
"key_c": {
"range": {
"min": 100,
"max": 1000
}
}
}
]
}
I am thinking my POJO for property object would look something like this.
class Property {
private String key;
private Value value;
}
It is possible to use inheritance for that. This is the classes for your example with Jackson
public class Sample {
#JsonProperty(value = "id")
Integer id;
#JsonProperty(value = "name")
String name;
#JsonProperty(value = "properties")
List<Property> properties;
}
#JsonTypeInfo(
use = JsonTypeInfo.Id.NAME,
include = JsonTypeInfo.As.WRAPPER_OBJECT)
#JsonSubTypes({
#JsonSubTypes.Type(value = KeyA.class, name = "key_a"),
#JsonSubTypes.Type(value = KeyB.class, name = "key_b"),
#JsonSubTypes.Type(value = KeyC.class, name = "key_c")
})
public abstract class Property {
}
public class KeyA extends Property{
Integer value;
public KeyA(Integer value) {
this.value = value;
}
#JsonValue
public Integer getValue() {
return value;
}
}
public class KeyB extends Property {
List<String> valueList;
#JsonCreator
public KeyB( List<String> valueList) {
this.valueList = valueList;
}
#JsonValue
public List<String> getValueList() {
return valueList;
}
}
public class KeyC extends Property {
#JsonProperty(value = "range")
Range value;
}
public class Range {
#JsonProperty(value = "min")
Integer min;
#JsonProperty(value = "max")
Integer max;
}
If I understand correctly you want to change to JSON and back. I wrote a small class for my own SpringBoot project, using ObjectMapper
#Component
public final class JsonUtils {
private final ObjectMapper mapper;
#Autowired
public JsonUtils(ObjectMapper mapper) {
this.mapper = mapper;
}
public String asJsonString(final Object object) {
try {
return mapper.registerModule(new JavaTimeModule())
.writeValueAsString(object);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
/*
* Customized Objectmapper for reading values compatible with this class' other methods
* #Return the desired object you want from a JSON
* IMPORTANT! -your return object should be a class that has a #NoArgsConstructor-
*/
public Object readValue(final String input, final Class<?> classToRead) {
try {
return mapper
.readValue(input, classToRead);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}`
Perhaps it can be of some use to you.

Deserializing an enum with Jackson (#JsonValue) [duplicate]

I'm using JAVA 1.6 and Jackson 1.9.9 I've got an enum
public enum Event {
FORGOT_PASSWORD("forgot password");
private final String value;
private Event(final String description) {
this.value = description;
}
#JsonValue
final String value() {
return this.value;
}
}
I've added a #JsonValue, this seems to do the job it serializes the object into:
{"event":"forgot password"}
but when I try to deserialize I get a
Caused by: org.codehaus.jackson.map.JsonMappingException: Can not construct instance of com.globalrelay.gas.appsjson.authportal.Event from String value 'forgot password': value not one of declared Enum instance names
What am I missing here?
The serializer / deserializer solution pointed out by #xbakesx is an excellent one if you wish to completely decouple your enum class from its JSON representation.
Alternatively, if you prefer a self-contained solution, an implementation based on #JsonCreator and #JsonValue annotations would be more convenient.
So leveraging on the example by #Stanley the following is a complete self-contained solution (Java 6, Jackson 1.9):
public enum DeviceScheduleFormat {
Weekday,
EvenOdd,
Interval;
private static Map<String, DeviceScheduleFormat> namesMap = new HashMap<String, DeviceScheduleFormat>(3);
static {
namesMap.put("weekday", Weekday);
namesMap.put("even-odd", EvenOdd);
namesMap.put("interval", Interval);
}
#JsonCreator
public static DeviceScheduleFormat forValue(String value) {
return namesMap.get(StringUtils.lowerCase(value));
}
#JsonValue
public String toValue() {
for (Entry<String, DeviceScheduleFormat> entry : namesMap.entrySet()) {
if (entry.getValue() == this)
return entry.getKey();
}
return null; // or fail
}
}
Note that as of this commit in June 2015 (Jackson 2.6.2 and above) you can now simply write:
public enum Event {
#JsonProperty("forgot password")
FORGOT_PASSWORD;
}
The behavior is documented here: https://fasterxml.github.io/jackson-annotations/javadoc/2.11/com/fasterxml/jackson/annotation/JsonProperty.html
Starting with Jackson 2.6 this annotation may also be used to change serialization of Enum like so:
public enum MyEnum {
#JsonProperty("theFirstValue") THE_FIRST_VALUE,
#JsonProperty("another_value") ANOTHER_VALUE;
}
as an alternative to using JsonValue annotation.
You should create a static factory method which takes single argument and annotate it with #JsonCreator (available since Jackson 1.2)
#JsonCreator
public static Event forValue(String value) { ... }
Read more about JsonCreator annotation here.
Actual Answer:
The default deserializer for enums uses .name() to deserialize, so it's not using the #JsonValue. So as #OldCurmudgeon pointed out, you'd need to pass in {"event": "FORGOT_PASSWORD"} to match the .name() value.
An other option (assuming you want the write and read json values to be the same)...
More Info:
There is (yet) another way to manage the serialization and deserialization process with Jackson. You can specify these annotations to use your own custom serializer and deserializer:
#JsonSerialize(using = MySerializer.class)
#JsonDeserialize(using = MyDeserializer.class)
public final class MyClass {
...
}
Then you have to write MySerializer and MyDeserializer which look like this:
MySerializer
public final class MySerializer extends JsonSerializer<MyClass>
{
#Override
public void serialize(final MyClass yourClassHere, final JsonGenerator gen, final SerializerProvider serializer) throws IOException, JsonProcessingException
{
// here you'd write data to the stream with gen.write...() methods
}
}
MyDeserializer
public final class MyDeserializer extends org.codehaus.jackson.map.JsonDeserializer<MyClass>
{
#Override
public MyClass deserialize(final JsonParser parser, final DeserializationContext context) throws IOException, JsonProcessingException
{
// then you'd do something like parser.getInt() or whatever to pull data off the parser
return null;
}
}
Last little bit, particularly for doing this to an enum JsonEnum that serializes with the method getYourValue(), your serializer and deserializer might look like this:
public void serialize(final JsonEnum enumValue, final JsonGenerator gen, final SerializerProvider serializer) throws IOException, JsonProcessingException
{
gen.writeString(enumValue.getYourValue());
}
public JsonEnum deserialize(final JsonParser parser, final DeserializationContext context) throws IOException, JsonProcessingException
{
final String jsonValue = parser.getText();
for (final JsonEnum enumValue : JsonEnum.values())
{
if (enumValue.getYourValue().equals(jsonValue))
{
return enumValue;
}
}
return null;
}
I've found a very nice and concise solution, especially useful when you cannot modify enum classes as it was in my case. Then you should provide a custom ObjectMapper with a certain feature enabled. Those features are available since Jackson 1.6. So you only need to write toString() method in your enum.
public class CustomObjectMapper extends ObjectMapper {
#PostConstruct
public void customConfiguration() {
// Uses Enum.toString() for serialization of an Enum
this.enable(WRITE_ENUMS_USING_TO_STRING);
// Uses Enum.toString() for deserialization of an Enum
this.enable(READ_ENUMS_USING_TO_STRING);
}
}
There are more enum-related features available, see here:
https://github.com/FasterXML/jackson-databind/wiki/Serialization-Features
https://github.com/FasterXML/jackson-databind/wiki/Deserialization-Features
Try this.
public enum Event {
FORGOT_PASSWORD("forgot password");
private final String value;
private Event(final String description) {
this.value = description;
}
private Event() {
this.value = this.name();
}
#JsonValue
final String value() {
return this.value;
}
}
I like the accepted answer. However, I would improve it a little (considering that there is now Java higher than version 6 available).
Example:
public enum Operation {
EQUAL("eq"),
NOT_EQUAL("ne"),
LESS_THAN("lt"),
GREATER_THAN("gt");
private final String value;
Operation(String value) {
this.value = value;
}
#JsonValue
public String getValue() {
return value;
}
#JsonCreator
public static Operation forValue(String value) {
return Arrays.stream(Operation.values())
.filter(op -> op.getValue().equals(value))
.findFirst()
.orElseThrow(); // depending on requirements: can be .orElse(null);
}
}
You can customize the deserialization for any attribute.
Declare your deserialize class using the annotationJsonDeserialize (import com.fasterxml.jackson.databind.annotation.JsonDeserialize) for the attribute that will be processed. If this is an Enum:
#JsonDeserialize(using = MyEnumDeserialize.class)
private MyEnum myEnum;
This way your class will be used to deserialize the attribute. This is a full example:
public class MyEnumDeserialize extends JsonDeserializer<MyEnum> {
#Override
public MyEnum deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException {
JsonNode node = jsonParser.getCodec().readTree(jsonParser);
MyEnum type = null;
try{
if(node.get("attr") != null){
type = MyEnum.get(Long.parseLong(node.get("attr").asText()));
if (type != null) {
return type;
}
}
}catch(Exception e){
type = null;
}
return type;
}
}
Here is another example that uses string values instead of a map.
public enum Operator {
EQUAL(new String[]{"=","==","==="}),
NOT_EQUAL(new String[]{"!=","<>"}),
LESS_THAN(new String[]{"<"}),
LESS_THAN_EQUAL(new String[]{"<="}),
GREATER_THAN(new String[]{">"}),
GREATER_THAN_EQUAL(new String[]{">="}),
EXISTS(new String[]{"not null", "exists"}),
NOT_EXISTS(new String[]{"is null", "not exists"}),
MATCH(new String[]{"match"});
private String[] value;
Operator(String[] value) {
this.value = value;
}
#JsonValue
public String toStringOperator(){
return value[0];
}
#JsonCreator
public static Operator fromStringOperator(String stringOperator) {
if(stringOperator != null) {
for(Operator operator : Operator.values()) {
for(String operatorString : operator.value) {
if (stringOperator.equalsIgnoreCase(operatorString)) {
return operator;
}
}
}
}
return null;
}
}
There are various approaches that you can take to accomplish deserialization of a JSON object to an enum. My favorite style is to make an inner class:
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonProperty;
import org.hibernate.validator.constraints.NotEmpty;
import java.util.Arrays;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collectors;
import static com.fasterxml.jackson.annotation.JsonFormat.Shape.OBJECT;
#JsonFormat(shape = OBJECT)
public enum FinancialAccountSubAccountType {
MAIN("Main"),
MAIN_DISCOUNT("Main Discount");
private final static Map<String, FinancialAccountSubAccountType> ENUM_NAME_MAP;
static {
ENUM_NAME_MAP = Arrays.stream(FinancialAccountSubAccountType.values())
.collect(Collectors.toMap(
Enum::name,
Function.identity()));
}
private final String displayName;
FinancialAccountSubAccountType(String displayName) {
this.displayName = displayName;
}
#JsonCreator
public static FinancialAccountSubAccountType fromJson(Request request) {
return ENUM_NAME_MAP.get(request.getCode());
}
#JsonProperty("name")
public String getDisplayName() {
return displayName;
}
private static class Request {
#NotEmpty(message = "Financial account sub-account type code is required")
private final String code;
private final String displayName;
#JsonCreator
private Request(#JsonProperty("code") String code,
#JsonProperty("name") String displayName) {
this.code = code;
this.displayName = displayName;
}
public String getCode() {
return code;
}
#JsonProperty("name")
public String getDisplayName() {
return displayName;
}
}
}
In the context of an enum, using #JsonValue now (since 2.0) works for serialization and deserialization.
According to the jackson-annotations javadoc for #JsonValue:
NOTE: when use for Java enums, one additional feature is that value returned by annotated method is also considered to be the value to deserialize from, not just JSON String to serialize as. This is possible since set of Enum values is constant and it is possible to define mapping, but can not be done in general for POJO types; as such, this is not used for POJO deserialization.
So having the Event enum annotated just as above works (for both serialization and deserialization) with jackson 2.0+.
Besides using #JsonSerialize #JsonDeserialize, you can also use SerializationFeature and DeserializationFeature (jackson binding) in the object mapper.
Such as DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE, which give default enum type if the one provided is not defined in the enum class.
In my case, this is what resolved:
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonProperty;
#JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum PeriodEnum {
DAILY(1),
WEEKLY(2),
;
private final int id;
PeriodEnum(int id) {
this.id = id;
}
public int getId() {
return id;
}
public String getName() {
return this.name();
}
#JsonCreator
public static PeriodEnum fromJson(#JsonProperty("name") String name) {
return valueOf(name);
}
}
Serializes and deserializes the following json:
{
"id": 2,
"name": "WEEKLY"
}
I hope it helps!
Here, 'value' acts as a deserialiser and 'namespace' acts as a serialiser. Hence, you can pass in value "Student Absent" to API while saving, and in DB it will be saved as "STUDENT_ABSENT". On the other hand, while retrieving data in your class, your API will return "Student Absent"
import com.fasterxml.jackson.annotation.JsonProperty;
public enum AttendanceEnums {
STUDENT_PRESENT,
#JsonProperty(value = "Student Absent", namespace = "Student Absent")
STUDENT_ABSENT;
}
I had been looking for a solution to enum serialization and I finally made a solution.
https://github.com/sirgilligan/EnumerationSerialization
https://digerati-illuminatus.blogspot.com/2022/10/java-enum-generic-serializer-and.html
It uses a new annotation and two new classes, EnumerationSerializer and EnumerationDeserializer. You can subclass the EnumerationDeserializer and make a class that sets the enum Class (typical approach) or you can annotate the enum and you don't have to have a subclass of EnumerationDeserializer.
#JsonSerialize(using = EnumerationSerializer.class)
#JsonDeserialize(using = EnumerationDeserializer.class)
#EnumJson(serializeProjection = Projection.NAME, deserializationClass = RGB.class)
enum RGB {
RED,
GREEN,
BLUE
}
Notice how the implementation of ContextualDeserializer pulls the class from the annotation.
https://github.com/sirgilligan/EnumerationSerialization/blob/main/src/main/java/org/example/EnumerationDeserializer.java
There is a lot of good code in this that might give insights.
For your specific question you could do this:
#JsonSerialize(using = EnumerationSerializer.class)
#JsonDeserialize(using = EnumerationDeserializer.class)
#EnumJson(serializeProjection = Projection.NAME, deserializationClass = Event.class)
public enum Event {
FORGOT_PASSWORD("forgot password");
//This annotation is optional because the code looks for value or alias.
#EnumJson(serializeProjection = Projection.VALUE)
private final String value;
private Event(final String description) {
this.value = description;
}
}
Or you could do this:
#JsonSerialize(using = EnumerationSerializer.class)
#JsonDeserialize(using = EnumerationDeserializer.class)
#EnumJson(serializeProjection = Projection.NAME, deserializationClass = Event.class)
public enum Event {
FORGOT_PASSWORD("forgot password");
private final String value;
private Event(final String description) {
this.value = description;
}
}
That's all you have to do.
Then if you have a class that "has a" event you can annotate each occurance to serialize the way you want.
class EventHolder {
#EnumJson(serializeProjection = Projection.NAME)
Event someEvent;
#EnumJson(serializeProjection = Projection.ORDINAL)
Event someOtherEvent;
#EnumJson(serializeProjection = Projection.VALUE)
Event yetAnotherEvent;
}
The simplest way I found is using #JsonFormat.Shape.OBJECT annotation for the enum.
#JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum MyEnum{
....
}
I did it like this :
// Your JSON
{"event":"forgot password"}
// Your class to map
public class LoggingDto {
#JsonProperty(value = "event")
private FooEnum logType;
}
//Your enum
public enum FooEnum {
DATA_LOG ("Dummy 1"),
DATA2_LOG ("Dummy 2"),
DATA3_LOG ("forgot password"),
DATA4_LOG ("Dummy 4"),
DATA5_LOG ("Dummy 5"),
UNKNOWN ("");
private String fullName;
FooEnum(String fullName) {
this.fullName = fullName;
}
public String getFullName() {
return fullName;
}
#JsonCreator
public static FooEnum getLogTypeFromFullName(String fullName) {
for (FooEnum logType : FooEnum.values()) {
if (logType.fullName.equals(fullName)) {
return logType;
}
}
return UNKNOWN;
}
}
So the value of the property "logType" for class LoggingDto will be DATA3_LOG
This post is old, but if it can help someone, use JsonFormat.Shape.STRING
#JsonFormat(shape = JsonFormat.Shape.STRING)
public enum SomeEnum{
#JsonProperty("SOME_PROPERTY")
someProperty,
...
}
Code results is like this
{"someenum":"SOME_PROPERTY"}
#JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum LoginOptionType {
PHONE(1, "Phone"), MAIL(2, "mail"), PERSONAL_EMAIL(3, "Personal email");
private static List<LoginOptionType> all;
static {
all = new ArrayList<LoginOptionType>() {
{
add(LoginOptionType.PHONE);
add(LoginOptionType.MAIL);
add(LoginOptionType.PERSONAL_EMAIL);
}
};
}
private final Integer viewValue;
private final String name;
LoginOptionType(Integer viewValue, String name) {
this.viewValue = viewValue;
this.name = name;
}
public Integer getViewValue() {
return viewValue;
}
public String getName() {
return name;
}
public static List<LoginOptionType> getAll() {
return all;
}
}
Response
[
{
"viewValue": 1,
"name": "Phone"
},
{
"viewValue": 2,
"name": "mail"
},
{
"viewValue": 3,
"name": "Personal email"
}
]

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