I would like to deserialize JSON of this structure:
{
"employee_pricing_type":"COMPUTE_BY_OWN_RATE",
"employee_rate":10,
"customer_pricing_type":"COMPUTE_BY_OWN_RATE",
"customer_rate":200
}
I have such POJO to create price setting from a HTTP request:
public class ObjectPricingSetting {
#JsonProperty("pricing_type") // describes output
private final ObjectPricingType pricingType;
#JsonProperty("own_rate") // describes output
private final BigDecimal ownRate;
public ObjectPricingSetting(final ObjectPricingType pricingType, final BigDecimal ownRate) {
AssertUtils.notNull(pricingType, "pricingType");
this.pricingType = pricingType;
if (ownRate != null) {
AssertUtils.isGtZero(ownRate, "ownRate");
this.ownRate = ownRate;
} else {
this.ownRate = null;
}
}
public ObjectPricingType getPricingType() {
return pricingType;
}
public BigDecimal getOwnRate() {
return ownRate;
}
}
this is DTO:
#JsonInclude(JsonInclude.Include.NON_NULL)
public class ObjectPricingCommand extends BaseDto<ObjectId> {
#JsonProperty(value = "employee_pricing_setting")
private ObjectPricingSetting employeePricingSetting;
#JsonProperty(value = "customer_pricing_setting")
private ObjectPricingSetting customerPricingSetting;
}
I would like to create these two instances of ObjectPricingSetting with #JsonCreator.
Q: How should I anotate #JsonProperty parameter in ObjectPricingSetting constructor to recognize what JSON value should use to create these two instances?
You can use #JsonUnwrapped with a prefix in your parent class:
#JsonInclude(JsonInclude.Include.NON_NULL)
public class ObjectPricingCommand extends BaseDto<ObjectId> {
#JsonUnwrapped(prefix = "employee_")
private ObjectPricingSetting employeePricingSetting;
#JsonUnwrapped(prefix = "customer_")
private ObjectPricingSetting customerPricingSetting;
}
Then you can use the normal #JsonCreator/#JsonProperty in your nested DTO, without the prefix:
public class ObjectPricingSetting {
#JsonCreator
public ObjectPricingSetting(
#JsonProperty("pricing_type") final ObjectPricingType pricingType,
#JsonProperty("rate") final BigDecimal ownRate) {
...
I have below classes:
public class Result<T> {
public int code;
public Object meta;
public T data;
}
public class User {
public int id;
public String name;
}
public class Error {
public String field;
public String message;
}
I want to deserialize a JSON payload based on code field. If code >= 10, return Result<ArrayList<Error>>, otherwise return Result<User>
Currently, I map JSON to Result<Object> first, then check the code field. Based on that value I make second map to desired object.
ObjectMapper mapper = new ObjectMapper();
Result<Object> tempResult = mapper.readValue(json, new TypeReference<Result<Object>>() {});
if (tempResult.code < 10) {
Result<User> result = mapper.readValue(json, new TypeReference<Result<User>>() {});
return result;
} else {
Result<ArrayList<Error>> result = mapper.readValue(json, new TypeReference<Result<ArrayList<Error>>>() {});
return result;
}
Is there an elegant way to do this without deserializing it 2 times?
You need to implement custom TypeIdResolver:
class UserTypeIdResolverBase extends TypeIdResolverBase {
#Override
public String idFromValue(Object value) {
throw new IllegalStateException("Not implemented!");
}
#Override
public String idFromValueAndType(Object value, Class<?> suggestedType) {
throw new IllegalStateException("Not implemented!");
}
#Override
public JsonTypeInfo.Id getMechanism() {
return JsonTypeInfo.Id.CUSTOM;
}
#Override
public JavaType typeFromId(DatabindContext context, String id) {
if (Integer.parseInt(id) < 10) {
return context.getTypeFactory().constructType(new TypeReference<Result<User>>() {});
}
return context.getTypeFactory().constructType(new TypeReference<Result<List<Error>>>() {});
}
}
and declare it for a Result class:
#JsonTypeInfo(property = "code", use = JsonTypeInfo.Id.CUSTOM, visible = true)
#JsonTypeIdResolver(UserTypeIdResolverBase.class)
class Result<T>
I have a Spring mvc application, with a #RestController like such:
#RestController
#RequestMapping("levels")
public class LevelController {
private final GetLevelOneCount getLevelOneCount;
private final GetLevelTwoCount getLevelTwoCount;
private final GetLevelThreeCount getLevelThreeCount;
#Inject
public LevelController(GetLevelOneCount getLevelOneCount,
GetLevelTwoCount getLevelTwoCount,
GetLevelThreeCount getLevelThreeCount) {
this.getLevelOneCount = getLevelOneCount;
this.getLevelTwoCount = getLevelTwoCount;
this.getLevelThreeCount = getLevelThreeCount;
}
#GetMapping("/level1/{id}")
public LevelModel levelOne(#PathVariable String id) throws SQLException {
LevelModel levelOneModel = new LevelModel();
levelOneModel.setLevelQuery(getLevelOneCount.execute(id));
levelOneModel.setLevelDirQuery(getLevelOneCount.executeDir(id));
levelOneModel.setLevelDateQuery(getLevelOneCount.executeDate(id));
return levelOneModel;
}
my LevelModel is a POJO with private variables, now i wonder, if this can get serialized to propper JSON with private variables?
package com.pwc.tag.service.levels;
public class LevelModel {
private Long LevelQuery;
private Long LevelDirQuery;
private Long LevelDateQuery;
public Long getLevelQuery() {
return LevelQuery;
}
public void setLevelQuery(Long levelQuery) {
LevelQuery = levelQuery;
}
public Long getLevelDirQuery() {
return LevelDirQuery;
}
public void setLevelDirQuery(Long levelDirQuery) {
LevelDirQuery = levelDirQuery;
}
public Long getLevelDateQuery() {
return LevelDateQuery;
}
public void setLevelDateQuery(Long levelDateQuery) {
LevelDateQuery = levelDateQuery;
}
}
Yes, your object will be serialized to a proper JSON structure including the private field, because of the getters and setters.
If these fields should not be present in the output object, you can add the #JsonIgnore annotation to exclude them from the JSON structure.
P.S. the common approach is to start names of java properties with a lower case letter.
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"
}
]
Disclaimer: I'm new to all this, so my terminology may be wrong
I've got some Java POJO's I want to serialize to JSON & XML. I'm using MOXy 2.5.0 for JSON and Jersey 2.4.1.
#XmlRootElement
class Root {
// #XmlElements({#XmlElement(name = "destination_address", type = LatLong.class),
// #XmlElement(name = "destination_address", type = Polygon.class)})
public Object[] destination_addresses;
}
public class LatLong {
public double lat, lng;
}
public class Polygon {
protected List<LatLong> points = new ArrayList<LatLong>();
#XmlElements({#XmlElement(name = "lat", type = Lat.class),
#XmlElement(name = "lng", type = Lng.class)})
private LatOrLong[] getLatOrLongs() {
LatOrLong[] retval = new LatOrLong[points.size() * 2];
for (int point = 0; point < points.size(); point++) {
LatLong latLong = points.get(point);
retval[point * 2] = new Lat(latLong.lat);
retval[point * 2 + 1] = new Lng(latLong.lng);
}
return retval;
}
static abstract private class LatOrLong {
#XmlValue
private double latOrLong;
private LatOrLong() {}
private LatOrLong(double latOrLong) {this.latOrLong = latOrLong;}
}
static private class Lat extends LatOrLong {
private Lat() {}
private Lat(double lat) {super(lat);}
}
static private class Lng extends LatOrLong {
private Lng() {}
private Lng(double lng) {super(lng);}
}
}
This doesn't work in XML with the two lines commented out, but in JSON, MOXy is adding a type: latLong attribute to the destination_addresses array, as well as using the toString() method of Polygon.
How can I hide the type?
How can I get MOXy to use getLatOrLongs() instead of toString()?
EDIT: I've simplified Polygon to just serialize points and changed destination_addresses to be a List<Object> instead of Object[] .
The pojo mapping feature is by default enabled using MOXy.
But if for any case, you need to implement a specific marshal/unmarshal (I take here ObjectID from MongoDB which is a t:
import javax.xml.bind.annotation.adapters.XmlAdapter;
import org.bson.types.ObjectId;
public class ObjectIdXmlAdapter extends XmlAdapter<String, ObjectId> {
#Override
public String marshal(ObjectId id) throws Exception {
if(id == null) {
return null;
} else {
return id.toString();
}
}
#Override
public ObjectId unmarshal(String id) throws Exception {
return new ObjectId(id);
}
}
And then, on your POJO:
#XmlJavaTypeAdapter(ObjectIdXmlAdapter.class)
public ObjectId getId() {
return id;
}
Will serialize your id element as expected...
Hope this helps, this should be the main trouble.