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Retrofit multiple response types

How can I use Retrofit2 to parse these two kinds of API responses?
Ok response (HTTP 200):
{
"data": {
"foo": "bar"
}
}
Error response (HTTP 200):
{
"error": {
"foo": "bar"
}
}
I've read tons of SO questions and tutorials, but I don't know how to do that, I've tried:
GsonBuilder gsonBuilder = new GsonBuilder();
gsonBuilder.registerTypeAdapterFactory(new ItemTypeAdapterFactory());
Gson gson = gsonBuilder.create();
final Retrofit retrofit = new Retrofit.Builder()
.client(getOkHttpClient())
.baseUrl(Constants.API_BASE_URL)
.addConverterFactory(GsonConverterFactory.create(gson))
.build();
And this is my ItemTypeAdapterFactory:
class ItemTypeAdapterFactory implements TypeAdapterFactory {
public <T> TypeAdapter<T> create(final Gson gson, final TypeToken<T> type) {
final TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type);
final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
return new TypeAdapter<T>() {
public void write(JsonWriter out, T value) throws IOException {
delegate.write(out, value);
}
public T read(JsonReader in) throws IOException {
JsonElement jsonElement = elementAdapter.read(in);
if (jsonElement.isJsonObject()) {
JsonObject jsonObject = jsonElement.getAsJsonObject();
// Data key
if (jsonObject.has(Constants.JSON_KEY_DATA)) {
JsonElement jsonData = jsonObject.get(Constants.JSON_KEY_DATA);
// Primitive
if (jsonData.isJsonPrimitive()) {
jsonElement = jsonData.getAsJsonPrimitive();
}
// JSON object
else if (jsonData.isJsonObject()) {
jsonElement = jsonData;
}
// JSON object array
else if (jsonData.isJsonArray()) {
jsonElement = jsonData.getAsJsonArray();
}
}
}
return delegate.fromJsonTree(jsonElement);
}
}.nullSafe();
}
}
But now I don't know the type to be declared on retrofit2 interface, inside Call:
#GET("login")
Call<?> login(#Query(Constants.API_PARAM_TOKEN) String token);
Could you please point me in the right direction?

In a similar case, I once used JsonObject as type, so your function will look like this:
#GET("login")
Call<?> login(#Query(Constants.API_PARAM_TOKEN) String token);
Next, when you make a retrofit call, you keep the response as a string. So, in your java code, do something like this:
Call<JsonObject> call = RetrofitClient.getAPIService().login('YOUR_INPUT');
Data data = null;
Error error = null;
call.enqueue(new Callback<JsonObject>() {
#Override
public void onResponse(Call<JsonObject> call, Response<JsonObject> response) {
if(response.isSuccessfull()){
String jsonString = response.body().toString();
if(jsonString.contains("data:")){
data = new Gson().fromJson(jsonString,Data.class);
}else{
error = new Gson().fromJson(jsonString,Error.class);
}
}
}
Here, I have used Data and Error these 2 classes. They are the POJOs. So Data can look something like this:
Data.java:
public class Data implements Serializable{
#SerializedName("foo")
#Expose
private Foo foo; // Foo is your desired data type
}
Same goes for Error. So depending on your rest of the code, make necessary changes. Good luck.

I used to do something like this
BaseResponse
public class BaseResponse<D,E>{
E error;
D data;
public boolean isSuccess(){
return error==null;
}
}
Retrofit interface
#GET("login")
Call<BaseResponse<LoginData,ErrorData>> login(#Query(Constants.API_PARAM_TOKEN) String token);
this approach will work OK when you have control over the REST API structure.
the only problem is that you need to check for success using isSuccess method for every request before using the data object.

Retrofit Gson custom json generic converter

I've been working with Retrofit on a couple of my projects before but now I want to do something slightly different. I'm calling an api that wraps my response in a structure similar to this:
{ // only for demo purposes. Probably errors and data will never be populated together
"body": {
"errors": {
"username": [
"Username is too short",
"Username already exists"
]
},
"data": {
"message": "User created."
}
}
}
I'm trying to convert all that to a generic class which will wrap that response for me. What I have in mind is something like
public class ApiResponse<T> {
private T data;
private Map<String, List<String>> errors;
public ApiResponse(T data, Map<String, List<String>> errors) {
this.data = data;
this.errors = errors;
}
}
Where T can be any class.
I tried implementing a JsonDeserializer<ApiResponse<T>> based on some examples I found around the internet but I can't wrap my head around how to make it work as much automatically as possible and let Retrofit and Gson do the heavy lifting
My Converter class is as follows:
public class ApiResponseDeserializer<T> implements JsonDeserializer<ApiResponse<T>> {
private Class clazz;
public ApiResponseDeserializer(Class clazz) {
this.clazz = clazz;
}
#Override
public ApiResponse deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
final JsonObject jsonObject = json.getAsJsonObject();
final JsonObject body = jsonObject.getAsJsonObject("body");
final JsonObject errors = body.getAsJsonObject("errors");
final JsonObject data = body.getAsJsonObject("data");
Map<String, List<String>> parsedErrors = new HashMap<>();
for(String key : errors.keySet()) {
List<String> errorsList = new ArrayList<>();
JsonArray value = errors.getAsJsonArray(key);
Iterator<JsonElement> valuesIterator = value.iterator();
while(valuesIterator.hasNext()) {
String error = valuesIterator.next().getAsString();
errorsList.add(error);
}
parsedErrors.put(key, errorsList);
}
T parsedData = context.deserialize(data, clazz);
return new ApiResponse<T>(parsedData, parsedErrors);
}
}
and then when building my retrofit client
public static Retrofit getClient() {
if (okHttpClient == null) {
initOkHttp();
}
Gson gson = new GsonBuilder()
.registerTypeAdapter(ApiResponse.class, new ApiResponseDeserializer<>(......) // PROBLEM
.create();
if (retrofit == null) {
retrofit = new Retrofit.Builder()
.baseUrl(Const.API_BASE_URL)
.client(okHttpClient)
.addCallAdapterFactory(RxJava2CallAdapterFactory.create())
.addConverterFactory(GsonConverterFactory.create(gson))
.build();
}
return retrofit;
}
But I feel like it's not generic enough to be able to convert my classes automatically. And also I have no idea how should I hint Gson what type my data.
My endpoints are defined as follows:
#POST("users/signup")
Single<ApiResponse<RegisterResponseData>> register(#Body RegisterRequest request);
But how do I make a generic Retrofit instance with a generic Gson type adapter that knows how to convert my response to a ApiResponse<RegisterResponseData>? And knows that the data property from the response should be converted to an object of type RegisterResponseData...

When you specify return type in Retrofit's client it's passed to Retrofit's converter as Type and then Gson receives that type which will be your ApiResponse<RegisterResponseData>. From that point Gson will understand that data is of type RegisterResponseData and will produce your model object.
Just try it without your ApiResponseDeserializer and you'll see it's working.
Edit:
Answering your additional question in comments:
If you want to skip your "body" object in json you can write your wrapper object like this:
public class ApiResponse<T> {
#SerializedName("body")
private ApiResponseBody<T> body;
public ApiResponse() {
}
public ApiResponse(ApiData<T> body) {
this.body = body;
}
}
public class ApiResponseBody<T> {
#SerializedName("data")
private T data;
#SerializedName("errors")
private Map<String, List<String>> errors;
public ApiResponseBody() {
}
public ApiResponseBody(T data, Map<String, List<String>> errors) {
this.data = data;
this.errors = errors;
}
}
And use it in usual way
#POST("users/signup")
Single<ApiResponse<RegisterResponseData>> register(#Body RegisterRequest request);

Gson treat failed field parsing as null

Is there a way to configure Gson so that it treats any failed field parse as null instead of throwing a parse exception? Ideally we could catch and log the exception -- but we want the option to keep going with the program even if some fields (or subfields) do not parse as expected.
Example:
Malformed JSON:
{
"dog": []
}
With classes:
class Farm {
public Dog dog;
}
class Dog {
public String name;
}
Gson gson = new Gson();
Farm oldMcdonald = gson.fromJson(json, Farm.class); // should not throw exception
assertNull(oldMcdonald.dog); // should pass

In Gson, it can be implemented pretty easy.
Despite the following solution, I guess, seems not to work in any case (for example, primitives), it can be enhanced if necessary.
final class JsonFailSafeTypeAdapterFactory
implements TypeAdapterFactory {
private static final TypeAdapterFactory instance = new JsonFailSafeTypeAdapterFactory();
private JsonFailSafeTypeAdapterFactory() {
}
static TypeAdapterFactory get() {
return instance;
}
#Override
public <T> TypeAdapter<T> create(final Gson gson, final TypeToken<T> typeToken) {
// We can support non-primitive types only
if ( typeToken.getRawType().isPrimitive() ) {
return null;
}
final TypeAdapter<T> delegateTypeAdapter = gson.getAdapter(typeToken);
return new JsonFailSafeTypeAdapter<>(delegateTypeAdapter);
}
private static final class JsonFailSafeTypeAdapter<T>
extends TypeAdapter<T> {
private final TypeAdapter<T> delegateTypeAdapter;
private JsonFailSafeTypeAdapter(final TypeAdapter<T> delegateTypeAdapter) {
this.delegateTypeAdapter = delegateTypeAdapter;
}
#Override
public void write(final JsonWriter out, final T value)
throws IOException {
delegateTypeAdapter.write(out, value);
}
#Override
public T read(final JsonReader in)
throws IOException {
try {
return delegateTypeAdapter.read(in);
} catch ( final MalformedJsonException | RuntimeException ignored ) {
// Once we get into unexpected JSON token, let's *always* consider a fallback to the default value
// Well, the default is always `null` anyway, but we'll do more work
return fallback(in);
}
}
private static <T> T fallback(final JsonReader in)
throws IOException {
final JsonToken jsonToken = in.peek();
switch ( jsonToken ) {
case BEGIN_ARRAY:
case BEGIN_OBJECT:
case NAME:
case STRING:
case NUMBER:
case BOOLEAN:
case NULL:
// Assume we're at the beginning of a complex JSON value or a JSON primitive
in.skipValue();
break;
case END_ARRAY:
// Not sure if we skipValue() can fast-forward this one
in.endArray();
break;
case END_OBJECT:
// The same
in.endObject();
break;
case END_DOCUMENT:
// do nothing
break;
default:
throw new AssertionError(jsonToken);
}
// Just return null (at least at the moment)
return null;
}
}
}
Now just register the above type factory to handle all types (except java.lang.Object if I'm not mistaken).
private static final Gson gson = new GsonBuilder()
.registerTypeAdapterFactory(JsonFailSafeTypeAdapterFactory.get())
.create();
public static void main(final String... args)
throws IOException {
try ( final JsonReader jsonReader = Resources.getPackageResourceJsonReader(Q50002961.class, "farm.json") ) {
final Farm oldMcdonald = gson.fromJson(jsonReader, Farm.class);
if ( oldMcdonald.dog != null ) {
throw new AssertionError();
}
System.out.println(oldMcdonald);
}
}
Example output:
q50002961.Farm#626b2d4a
Another option is also specifying target fields if there is no need to register the factory globally. For instance:
final class Farm {
#JsonAdapter(JsonFailSafeTypeAdapterFactory.class)
final Dog dog = null;
}

I will post a solution for your problem but it would still require you to change the code on your side. For example if you have configured a property as an object and you receive an array - there is no way to map that properly. So I would suggest to change everything in your code to List and write a custom mapper that creates a list with one element when an object is received. This way you will be flexible to what you receive but you will also need to add some logic to handle problems when you have more than one objects to the array. For your example what would you do if you get 2 dogs? What is the correct behavior?
So I would do it like that:
public class MainClass {
public static <T> void main(String[] args) throws IOException {
Gson gson = new GsonBuilder().registerTypeAdapterFactory(new ArrayAdapterFactory()).create();
// Here I do the opposite - add one dog but expect a collection
String json = "{ \"dog\": {name=\"Snoopy\"} }";
Farm oldMcdonald = gson.fromJson(json, Farm.class); // should not throw exception
System.out.println("Dog:"+oldMcdonald.dog.get(0).name); //Works properly
}
}
class Farm {
#Expose
public List<Dog> dog; //All such properties become a list. You handle the situation when there are more than one values
}
class Dog {
#Expose
public String name;
}
class ArrayAdapter<T> extends TypeAdapter<List<T>> {
private Class<T> adapterclass;
public ArrayAdapter(Class<T> adapterclass) {
this.adapterclass = adapterclass;
}
public List<T> read(JsonReader reader) throws IOException {
List<T> list = new ArrayList<T>();
Gson gson = new GsonBuilder()
.registerTypeAdapterFactory(new ArrayAdapterFactory())
.create();
if (reader.peek() == JsonToken.BEGIN_OBJECT) {
T inning = gson.fromJson(reader, adapterclass);
list.add(inning);
// return null; here if you want to return null instead of list with one element
} else if (reader.peek() == JsonToken.BEGIN_ARRAY) {
reader.beginArray();
while (reader.hasNext()) {
T inning = gson.fromJson(reader, adapterclass);
list.add(inning);
}
reader.endArray();
}
return list;
}
public void write(JsonWriter writer, List<T> value) throws IOException {
}
}
class ArrayAdapterFactory implements TypeAdapterFactory {
#SuppressWarnings({ "unchecked", "rawtypes" })
#Override
public <T> TypeAdapter<T> create(final Gson gson, final TypeToken<T> type) {
TypeAdapter<T> typeAdapter = null;
try {
if (type.getRawType() == List.class)
typeAdapter = new ArrayAdapter(
(Class) ((ParameterizedType) type.getType())
.getActualTypeArguments()[0]);
} catch (Exception e) {
e.printStackTrace();
}
return typeAdapter;
}
}
Thanks to http://sachinpatil.com/blog/2012/07/03/gson/ for the idea

Gson: parsing a non-standard JSON format

Does Gson have a way to read in non-standard JSON files?
Instead of a typical file like:
[{obj1},{objN}]
I have a file like this:
{obj1}
{objN}
Where there are no square brackets or commas and each object is separated by a newline character.

Yes, it has. Gson supports lenient reading. For example, the following JSON document (non-standard.json):
{
"foo": 1
}
{
"bar": 1
}
you can use the following reading way:
private static final Gson gson = new Gson();
private static final TypeAdapter<JsonElement> jsonElementTypeAdapter = gson.getAdapter(JsonElement.class);
public static void main(final String... args)
throws IOException {
try ( final Reader reader = getPackageResourceReader(Q43528208.class, "non-standard.json") ) {
final JsonReader jsonReader = new JsonReader(reader);
jsonReader.setLenient(true); // this makes it work
while ( jsonReader.peek() != END_DOCUMENT ) {
final JsonElement jsonElement = jsonElementTypeAdapter.read(jsonReader);
System.out.println(jsonElement);
}
}
}
Output:
{"foo":1}
{"bar":1}
I'm not sure if you can write a robust deserializer this way though.
Update
In order to simplify the Gson support, we can implement a few convenient reading methods:
// A shortcut method for the below implementation: aggregates the whole result into a single list
private static <T> List<T> parseToListLenient(final JsonReader jsonReader, final IMapper<? super JsonReader, ? extends T> mapper)
throws IOException {
final List<T> list = new ArrayList<>();
parseLenient(jsonReader, in -> list.add(mapper.map(in)));
return list;
}
// A convenient strategy-accepting method to configure a JsonReader instance to make it lenient and do read
// The consumer defines the strategy what to do with the current JsonReader token
private static void parseLenient(final JsonReader jsonReader, final IConsumer<? super JsonReader> consumer)
throws IOException {
final boolean isLenient = jsonReader.isLenient();
try {
jsonReader.setLenient(true);
while ( jsonReader.peek() != END_DOCUMENT ) {
consumer.accept(jsonReader);
}
} finally {
jsonReader.setLenient(isLenient);
}
}
// Since Java 8 Consumer inteface does not allow checked exceptions to be rethrown
private interface IConsumer<T> {
void accept(T value)
throws IOException;
}
private interface IMapper<T, R> {
R map(T value)
throws IOException;
}
Then simple reading is really simple, and we can just use the methods above:
final Gson gson = new Gson();
final TypeToken<Map<String, Integer>> typeToken = new TypeToken<Map<String, Integer>>() {
};
final TypeAdapter<Map<String, Integer>> typeAdapter = gson.getAdapter(typeToken);
try ( final JsonReader jsonReader = getPackageResourceJsonReader(Q43528208.class, "non-standard.json") ) {
final List<Map<String, Integer>> maps = parseToListLenient(jsonReader, typeAdapter::read);
System.out.println(maps);
}
Deserialization via Gson directly would require more complicated implementation:
// This is just a marker not meant to be instantiated but to create a sort of "gateway" to dispatch types in Gson
#SuppressWarnings("unused")
private static final class LenientListMarker<T> {
private LenientListMarker() {
throw new AssertionError("must not be instantiated");
}
}
private static void doDeserialize()
throws IOException {
final Gson gson = new GsonBuilder()
.registerTypeAdapterFactory(new TypeAdapterFactory() {
#Override
public <T> TypeAdapter<T> create(final Gson gson, final TypeToken<T> typeToken) {
// Check if the given type is the lenient list marker class
if ( !LenientListMarker.class.isAssignableFrom(typeToken.getRawType()) ) {
// Not the case? Just delegate the job to Gson
return null;
}
final Type listElementType = getTypeParameter0(typeToken.getType());
final TypeAdapter<?> listElementAdapter = gson.getAdapter(TypeToken.get(listElementType));
#SuppressWarnings("unchecked")
final TypeToken<List<?>> listTypeToken = (TypeToken<List<?>>) TypeToken.getParameterized(List.class, listElementType);
final TypeAdapter<List<?>> listAdapter = gson.getAdapter(listTypeToken);
final TypeAdapter<List<?>> typeAdapter = new TypeAdapter<List<?>>() {
#Override
public void write(final JsonWriter out, final List<?> value)
throws IOException {
// Always write a well-formed list
listAdapter.write(out, value);
}
#Override
public List<?> read(final JsonReader in)
throws IOException {
// Delegate the job to the reading method - we only have to tell how to obtain the list values
return parseToListLenient(in, listElementAdapter::read);
}
};
#SuppressWarnings("unchecked")
final TypeAdapter<T> castTypeAdapter = (TypeAdapter<T>) typeAdapter;
return castTypeAdapter;
}
// A simple method to resolve actual type parameter
private Type getTypeParameter0(final Type type) {
if ( !(type instanceof ParameterizedType) ) {
// List or List<?>
return Object.class;
}
return ((ParameterizedType) type).getActualTypeArguments()[0];
}
})
.create();
// This type declares a marker specialization to be used during deserialization
final Type type = new TypeToken<LenientListMarker<Map<String, Integer>>>() {
}.getType();
try ( final JsonReader jsonReader = getPackageResourceJsonReader(Q43528208.class, "non-standard.json") ) {
// This is where we're a sort of cheating:
// We tell Gson to deserialize LenientListMarker<Map<String, Integer>> but the type adapter above will return a list
final List<Map<String, Integer>> maps = gson.fromJson(jsonReader, type);
System.out.println(maps);
}
}
The output is now for Map<String, Integer>s, not JsonElements:
[{foo=1}, {bar=1}]
Update 2
TypeToken.getParameterized workaround:
#SuppressWarnings("unchecked")
final TypeToken<List<?>> listTypeToken = (TypeToken<List<?>>) TypeToken.get(new ParameterizedType() {
#Override
public Type getRawType() {
return List.class;
}
#Override
public Type[] getActualTypeArguments() {
return new Type[]{ listElementType };
}
#Override
public Type getOwnerType() {
return null;
}
});

We can have one more program to introduce comma(,) and construct a well formed JSON

With spark 2, we can add multiline as read option.
spark.df.option("multiline","true").json("data.json")

Gson custom serialization

I wish to have a custom GSON deserializer such that whenever it is deserializing a JSON object (i.e. anything within curly brackets { ... }), it will look for a $type node and deserialize using its inbuilt deserializing capability to that type. If no $type object is found, it just does what it normal does.
So for example, I would want this to work:
{
"$type": "my.package.CustomMessage"
"payload" : {
"$type": "my.package.PayloadMessage",
"key": "value"
}
}
public class CustomMessage {
public Object payload;
}
public class PayloadMessage implements Payload {
public String key;
}
Calling: Object customMessage = gson.fromJson(jsonString, Object.class).
So currently if I change the payload type to the Payload interface:
public class CustomMessage {
public Payload payload;
}
Then the following TypeAdapaterFactory will do what I want:
final TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type);
final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
final PojoTypeAdapter thisAdapter = this;
public T read(JsonReader reader) throws IOException {
JsonElement jsonElement = (JsonElement)elementAdapter.read(reader);
if (!jsonElement.isJsonObject()) {
return delegate.fromJsonTree(jsonElement);
}
JsonObject jsonObject = jsonElement.getAsJsonObject();
JsonElement typeElement = jsonObject.get("$type");
if (typeElement == null) {
return delegate.fromJsonTree(jsonElement);
}
try {
return (T) gson.getDelegateAdapter(
thisAdapter,
TypeToken.get(Class.forName(typeElement.getAsString()))).fromJsonTree(jsonElement);
} catch (ClassNotFoundException ex) {
throw new IOException(ex.getMessage());
}
}
However, I would like it to work when payload is of type Object or any type for that matter, and throw some sort of type match exception if it can't assign the variable.

Looking at the source for Gson, I have found what I think is the issue:
// built-in type adapters that cannot be overridden
factories.add(TypeAdapters.JSON_ELEMENT_FACTORY);
factories.add(ObjectTypeAdapter.FACTORY);
// user's type adapters
factories.addAll(typeAdapterFactories);
As you can see the ObjectTypeAdapter will take precedence over my factory.
The only solution as far as I can see is to use reflection to remove the ObjectTypeAdapter from the list or insert my factory before it. I have done this and it works.

I don't know how you can achieve it with Gson but you have such a feature in Genson by default.
To enable it just do:
Genson genson = new Genson.Builder().setWithClassMetadata(true).create();
You can also register aliases for your class names:
Genson genson = new Genson.Builder().addAlias("myClass", my.package.SomeClass.class).create();
This has however some limitations:
at the moment you can't change the key used to identify the type, it is #class
it must be present in your json before the other properties - but looks fine as it is the case in your examples
Works only with json objects and not arrays or litterals

This code skeleton works on your example but should be improved and tested with different scenarios.
public class PojoTypeAdapaterFactory implements TypeAdapterFactory {
#Override
public <T> TypeAdapter<T> create(final Gson gson, final TypeToken<T> type) {
// check types we support
if (type.getRawType().isAssignableFrom(CustomMessage.class) || type.getRawType().isAssignableFrom(PayloadMessage.class)) {
return new PojoTypeAdapter<T>(gson, type);
}
else return null;
}
private class PojoTypeAdapter<T> extends TypeAdapter<T> {
private Gson gson;
private TypeToken<T> type;
private PojoTypeAdapter(final Gson gson, final TypeToken<T> type) {
this.gson = gson;
this.type = type;
}
public T read(JsonReader reader) throws IOException {
final TypeAdapter<T> delegate = gson.getDelegateAdapter(PojoTypeAdapaterFactory.this, this.type);
final TypeAdapter<JsonElement> elementAdapter = this.gson.getAdapter(JsonElement.class);
JsonElement jsonElement = elementAdapter.read(reader);
if (!jsonElement.isJsonObject()) {
return (T) this.gson.getAdapter(JsonElement.class).fromJsonTree(jsonElement);
}
JsonObject jsonObject = jsonElement.getAsJsonObject();
JsonElement typeElement = jsonObject.get("$type");
if (typeElement == null) {
return delegate.fromJsonTree(jsonElement);
}
try {
final Class myClass = Class.forName(typeElement.getAsString());
final Object myInstance = myClass.newInstance();
final JsonObject jsonValue = jsonElement.getAsJsonObject().get("value").getAsJsonObject();
for (Map.Entry<String, JsonElement> jsonEntry : jsonValue.entrySet()) {
final Field myField = myClass.getDeclaredField(jsonEntry.getKey());
myField.setAccessible(true);
Object value = null;
if (jsonEntry.getValue().isJsonArray()) {
//value = ...;
}
else if (jsonEntry.getValue().isJsonPrimitive()) {
final TypeAdapter fieldAdapter = this.gson.getAdapter(myField.getType());
value = fieldAdapter.fromJsonTree(jsonEntry.getValue());
}
else if (jsonEntry.getValue().isJsonObject()) {
value = this.fromJsonTree(jsonEntry.getValue());
}
myField.set(myInstance, value);
}
return (T) myInstance;
}
catch (ClassNotFoundException | IllegalAccessException | IllegalArgumentException | InstantiationException | NoSuchFieldException | SecurityException e) {
throw new IOException(e);
}
}
#Override
public void write(final JsonWriter out, final T value) throws IOException {
out.beginObject();
out.name("$type");
out.value(value.getClass().getName());
out.name("value");
final TypeAdapter<T> delegateAdapter = (TypeAdapter<T>) this.gson.getDelegateAdapter(PojoTypeAdapaterFactory.this, TypeToken.<T>get(value.getClass()));
delegateAdapter.write(out, value);
out.endObject();
}
}
}
The generated JSON is not exactly the same though, as it contains an additional value entry:
{
"$type": "my.package.CustomMessage",
"value": {
"payload": {
"$type": "my.package.PayloadMessage",
"value": {
"key": "hello"
}
}
}
}