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"
}
]
Related
I have a simple class as property of mage:
// getter/setter omitted for brevity
public class Magic() {
String Spell;
int strength;
}
public class Mage() {
String name;
Magic magic;
}
I need to deserialize JSON from 2 different source strings:
{
"name" : "Sauron",
"magic" : {
"spell" : "Tamador",
"strenght" : 10
}
}
and
{
"name" : "Gandalf",
"magic" : "You shall not pass"
}
or even "You shall not pass" -> Magic object
I thought going with #JsonDeserialize(using = MagicDeserializer.class) would be the way to go with Jackson, but the Parser barfs with "Unrecognized token". Is there a way I can intercept the loading to do my own parsing?
The idea of a custom deserializer is correct, you can extends the StdDeserializer class and in its deserialize method convert the json to a JsonNode separating the two Stringand Object distinct values associated to the magic key in the json:
public class MagicDeserializer extends StdDeserializer<Magic> {
public MagicDeserializer() {
super(Magic.class);
}
#Override
public Magic deserialize(JsonParser jp, DeserializationContext dc) throws IOException, JsonProcessingException {
final ObjectCodec codec = jp.getCodec();
JsonNode root = codec.readTree(jp);
Magic magic = new Magic();
if (root.isTextual()) { //<- magic is a string
magic.setSpell(root.textValue());
return magic;
}
//ok, so magic is an Magic object
return codec.treeToValue(root, Magic.class);
}
}
Then if you annotate your Magic field you can deserialize both the jsons:
#Data
public class Mage {
private String name;
#JsonDeserialize(using = MagicDeserializer.class)
private Magic magic;
}
#Data
public class Magic {
private String Spell;
private int strength;
}
Mage sauron = mapper.readValue(json1, Mage.class);
System.out.println(mapper.writeValueAsString(sauron));
Mage gandalf = mapper.readValue(json2, Mage.class);
System.out.println(mapper.writeValueAsString(gandalf));
Is there a way to deserialize an enum which works for both the name and the object notation. I do want to keep the Shape as object for the deserialization though
e.g. This works for "type": {"name":"MYENUM"}, but what would I need to add to have it also work for "type": "MYENUM"
#JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum MyType {
#JsonProperty("MYENUM")
MYENUM("MyEnum")
public final String name = name();
MyType(String value) {
this.value = value;
}
#JsonCreator
public static MyType deserialize (#JsonProperty("name") String name) {
return MyType.valueOf(name);
}
}
Have tried adding a delegate like this
#JsonCreator(mode=JsonCreator.Mode.DELEGATING)
public static MyType deserializeString (String name) {
return MyType.valueOf(name);
}
One way to solve your problem is a custom deserializer extending StdDeserializer and inside of it check if your json file is in the form of "type": {"name":"MYENUM"} or {"type": "MYENUM"}. This checking can be obtained with the JsonNode#isObject method :
public class MyTypeDeserializer extends StdDeserializer<MyType> {
public MyTypeDeserializer() {
this(null);
}
public MyTypeDeserializer(Class<?> vc) {
super(vc);
}
#Override
public MyType deserialize(JsonParser jp, DeserializationContext dc) throws IOException, JsonProcessingException {
JsonNode root = jp.getCodec().readTree(jp);
JsonNode nodeType = root.get("type");
String name = nodeType.isObject() ? nodeType.get("name").asText() : nodeType.asText();
return MyType.valueOf(name);
}
}
Then you can annotate your MyType enum with the #JsonDeserialize(using = MyTypeDeserializer.class) deleting your deserialize method like below :
#JsonDeserialize(using = MyTypeDeserializer.class)
#JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum MyType { //omitted fields and methods for brevity }
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???
I want to use Jackson JSON to serialize/deserialize a class containing an enum object. My class is:
class Bar {
#JsonProperty("rateType")
#JsonDeserialize(using = ReturnedRateTypeDeserializer.class)
private ReturnedRateType rateType;
public ReturnedRateType getRateType() {
return rateType;
}
public void setRateType(ReturnedRateType rateType) {
this.rateType = rateType;
}
}
The enum class ReturnedRateType is defined as:
#JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum ReturnedRateType {
AA("AA"),
BB("BB"),
CC("CC");
#JsonProperty("value")
private String value;
ReturnedRateType(String value) {
this.value = value;
}
#JsonCreator
public static ReturnedRateType fromValue(final String value) {
if (value != null) {
for (ReturnedRateType type : ReturnedRateType.values()) {
if (value.equalsIgnoreCase(type.value)) {
return type;
}
}
}
return null;
}
}
As you see, I added #JsonFormat annotation to tell Jackson to serialize this enum as POJO, and added #JsonCreator annotation to get a static factory method from given string to enum object. Since Jackson can only serialize but can't deserialize from object representation to enum, I added the following customized deserializer for the enum ReturnedRateType:
public class ReturnedRateTypeDeserializer extends JsonDeserializer<ReturnedRateType> {
#Override
public ReturnedRateType deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
ReturnedRateType type = ReturnedRateType.fromValue(jp.getValueAsString());
if(type != null)
return type;
throw new JsonMappingException("invalid value for ReturnedRateType");
}
}
But when I tested deserialization from a JSON string to enum, I got the error. The JSON string is:
{"rateType": {"value": "AA"}}
My test code is:
#Test
public void RateTypeToEnum() {
String json = "{\"rateType\": {\"value\": \"AA\"}}";
System.out.println(json);
ObjectMapper mapper = new ObjectMapper();
Bar bar = null;
try {
bar = mapper.readValue(json, Bar.class);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(bar.getRateType());
}
I expect to see the output should be AA. But jp.getValueAsString() in my customized deserializer ReturnedRateTypeDeserializer is null during the execution:
ReturnedRateType type = ReturnedRateType.fromValue(jp.getValueAsString()); //jp.getValueAsString() is null here!
Thus it returns error. So what is wrong here?
According to the Jackson 2.5.X documentation on the JsonFormat annotation the Shape.Object does not work for the enum deserialisation:
Enums: Shapes JsonFormat.Shape.STRING and JsonFormat.Shape.NUMBER can
be used to change between numeric (index) and textual (name or
toString()); but it is also possible to use JsonFormat.Shape.OBJECT
to serialize (but not deserialize).
I'd make the JsonCreator static method accept a JsonNode and read the string value from it.
Note that this would work since 2.5.X. In early versions you would need to write a custom deserialiser. Here is an example:
public class JacksonEnumObjectShape {
#JsonFormat(shape = JsonFormat.Shape.OBJECT)
#JsonDeserialize(using = ReturnedRateTypeDeserializer.class)
public enum ReturnedRateType {
AA("AA"),
BB("BB"),
CC("CC");
#JsonProperty("value")
private String value;
ReturnedRateType(String value) {
this.value = value;
}
#JsonCreator
public static ReturnedRateType fromValue(final JsonNode jsonNode) {
for (ReturnedRateType type : ReturnedRateType.values()) {
if (type.value.equals(jsonNode.get("value").asText())) {
return type;
}
}
return null;
}
}
// can be avoided since 2.5
public static class ReturnedRateTypeDeserializer extends JsonDeserializer<ReturnedRateType> {
#Override
public ReturnedRateType deserialize(
final JsonParser jp,
final DeserializationContext ctxt) throws IOException {
final JsonNode jsonNode = jp.readValueAsTree();
return ReturnedRateType.fromValue(jsonNode);
}
}
public static void main(String[] args) throws IOException {
final ObjectMapper mapper = new ObjectMapper();
final String json = mapper.writeValueAsString(ReturnedRateType.AA);
System.out.println(json);
System.out.println(mapper.readValue(json, ReturnedRateType.class));
}
}
Output:
{"value":"AA"}
AA
I have a situation where I am passing back n forth an object from Java to Javascript client and it's being serialized by the built in Jackson mapper in Spring 3 (using the #RequestBody / #ResponseBody and application/json content type)
The problem I have is some classes implement from an interface which has a getter but no setter.
I do want the getter value available from the client side so I cannot use #JsonIgnore annotation because then it ignores the property entirely, both serializing and deserializing. I need the property when serialized.
Any other way to do this?
There is probably an easier way, but I thought to mention the usage of JSON views as a possible solution. There's an example on this thread.
You might need a different view on deserialization and not just on serialization, and that would be a Jackson 2.0 feature - supported by Spring 3.2 and backported into Spring 3.1. Using a view on serialization only is a feature since Jackson 1.4.
Another option that comes to mind is using a custom deserializer.
I was looking for the same thing.
According to the Jackson docs, we can set a #JsonIgnore annotation on a property, getter or setter and that would hide the complete property, unless we give the setter a #JsonProperty annotation that would make sure this property is visible when setting it. Unfortunately, that doesn't work the other way around. I wanted to show the property in my response, but not include it in my request.
Use case is an auto generated id for example. I don't want the user to set, or even see that, but he may read it.
You can achieve this by hiding the attribute itself indeed and then add a #JsonAnyGetter method. In this method you can massage the data to any form you want. It's also useful to represent complex attribute classes of which you only want to show a single name or identifier or other formatting. There are better ways of doing the latter, but if the use case is not too complex, this suffices.
So as example (My apologies if this is too elaborate):
User:
public class User {
private String uid;
private String customerId;
private String taxSsnId;
public String getUid() {
return uid;
}
public void setUid(String uid) {
this.uid = uid;
}
public String getCustomerId() {
return extCustomerId;
}
public void setCustomerId(String extCustomerId) {
this.extCustomerId = extCustomerId;
}
public String getTaxSsnId() {
return taxSsnId;
}
public void setTaxSsnId(String taxSsnId) {
this.taxSsnId = taxSsnId;
}
#JsonIgnore
public void getId(){
if (getUid() != null){
return getUid();
}
if (getCustomerId() != null ){
return getCustomerId();
}
return null;
}
}
Setting:
public class Setting {
#JsonIgnore
private int id;
private String key;
private String value;
#JsonIgnore
private User lastUpdatedBy;
#JsonIgnore
private Date lastUpdatedAt;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getKey() {
return key;
}
public void setKey(String key) {
this.key = key;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
public User getLastUpdatedBy() {
return lastUpdatedBy;
}
public void setLastUpdatedBy(User lastUpdatedBy) {
this.lastUpdatedBy = lastUpdatedBy;
}
public Date getLastUpdatedAt() {
return lastUpdatedAt;
}
public void setLastUpdatedAt(Date lastUpdatedAt) {
this.lastUpdatedAt = lastUpdatedAt;
}
#JsonAnyGetter
private Map<String, String> other() {
Map<String, String> map = new LinkedHashMap<String, String>();
map.put( "id", this.getId());
map.put( "lastUpdatedBy", this.getLastUpdatedBy().getId());
SimpleDateFormat format = new SimpleDateFormat("E, dd MMM yyyy HH:mm:ss z");
map.put( "lastUpdatedAt", format.format(this.getLastUpdatedAt()) );
return map;
}
}
Yields this Request schema (de-serialization view):
{
"key": "string",
"value": "string"
}
and this Response schema (serialized view):
{
"key": "string",
"value": "string",
"id": "12345",
"lastUpdatedBy": "String",
"lastUpdatedAt": "String"
}