Develop Reference

how can I work with wrapped data using moshi, retrofit and java?

I'm working with an API where all data are wrapped in a custom object (see below), so I cannot use moshi to convert the retrofit body direct to my models. What is the best way to work with moshi in this case?
#COLLECTIONS ENDPOINT
{
"status": 200,
"data": [
{
"id": 28122,
"name": "Abandonei",
"counts": {
"books": 3
}
},
{
"id": 21091,
"name": "Lendo",
"counts": {
"books": 6
}
},
],
"errors": [],
"pagination": {
"after": 2,
"hasNextPage": true
}
}
The same json structure is used in all api endpoints, the default fields are:
{
"status": 200,
"data": [],
"errors": [],
"pagination": {
"after": 1,
"hasNextPage": true
}
}
My Collection model:
public class BookCollection {
public long id;
public String name;
public ArrayList<Book> books;
public BookCollection(long id, String name) {
this.id = id;
this.name = name;
}
}

To avoid create a parent class to each model, I have implemented a way to use a class that receive a generic type.
To put this to work I've changed the Moshi class to Gson.
My model:
public class BookCollection {
public long id;
public String name;
public ArrayList<Book> books;
public BookCollection(long id, String name) {
this.id = id;
this.name = name;
}
}
The wrapper class used to unwrap the json data:
public class ApiWrapper<T> {
public final int status;
public final T data;
public final List<ApiError> errors = new ArrayList<>();
public ApiWrapper(int status, T data, List<ApiError> errors) {
this.status = status;
this.data = data;
this.errors.addAll(errors);
}
}
The Errors class, referenced in the class above:
public class ApiError {
public int code;
public String message;
public String error;
}
Usage:
public interface NetAPI {
#GET("me/collections")
Call<ResponseBody> getCollections(#Header("Authorization") String auth);
}
public class CollectionViewModel extends ViewModel {
private final MutableLiveData<List<Collection>> collections = new MutableLiveData<>();
private final MutableLiveData<Boolean> loading = new MutableLiveData<>();
private final MutableLiveData<Boolean> collectionError = new MutableLiveData<>();
private Call<ResponseBody> call;
private void fetchCollections() {
loading.setValue(true);
call = Api.getInstance().getCollections(TOKEN);
call.enqueue(new Callback<ResponseBody>() {
#Override
public void onResponse(Call<ResponseBody> call, Response<ResponseBody> response) {
try {
collectionError.setValue(false);
//THE SECRET
Gson gson = new Gson();
ApiWrapper<List<Collection>> apiResponse = null;
apiResponse = gson.fromJson(response.body().string(), new TypeToken<ApiWrapper<List<Collection>>>(){}.getType());
collections.setValue(apiResponse.data);
loading.setValue(false);
} catch (IOException e) {
e.printStackTrace();
}
}
#Override
public void onFailure(Call<ResponseBody> call, Throwable t) {
Log.e(getClass().getSimpleName(), "Error loading data", t);
collectionError.setValue(true);
loading.setValue(false);
}
});
}
}
At this way I can reuse my ApiWrapper class to any model (Books, Users, Login, etc).
Thanks.

You will need to setup gson/moshi to use your classes that you have created for the json to object mapping. Here is an example of what those java classes would look like. You can use data classes in kotlin as well. For moshi, you will have to create the adapter to help with the json to object mapping.
publci class CollectionResponse {
public int status;
public List<BookCollection> data;
public List<Error> errors;
public Pagination pagination;
}
public class Pagination {
public int after;
public boolean hasNextPage;
}
public class BookCollection {
public long id;
public String name;
public Count counts;
}
public Count {
public int books;
}
public class Error {
}

How to show a list in Android by using retrofit library?

I have to show A list in an Activity
MY API key is:
http://api.cuidadotechnologies.com/NSSPL/leave_dtls.php
Using GSON converter and retrofit library.
this API throws response in JSON like this
{
"status": 0,
"response_data": [
{
"id": "12",
"uid": "USER00000003",
"reason": "Test",
"type": "Plan Leave",
"SataDate": "2018-09-18",
"EndDate": "2018-09-25",
"ApprovedBy": "USER00000002",
"ApprovedDate": "2018-09-18",
"Status": "REJECTED",
"Remarks": "Test Reject"
},
{
"id": "13",
"uid": "USER00000003",
"reason": "Wedding",
"type": "Plan Leave",
"SataDate": "2018-01-28",
"EndDate": "2018-02-05",
"ApprovedBy": "USER00000002",
"ApprovedDate": "2018-09-18",
"Status": "APPROVED",
"Remarks": "Ok"
}
]
}
I am novice in this method please help me to do this step by step.

Try this way..
make retrofit object..
public class ApiClient {
private final static String BASE_URL = "http://api.cuidadotechnologies.com/NSSPL/";
public static ApiClient apiClient;
private Retrofit retrofit = null;
public static ApiClient getInstance() {
if (apiClient == null) {
apiClient = new ApiClient();
}
return apiClient;
}
//private static Retrofit storeRetrofit = null;
public Retrofit getClient() {
return getClient(null);
}
private Retrofit getClient(final Context context) {
HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
OkHttpClient.Builder client = new OkHttpClient.Builder();
client.readTimeout(60, TimeUnit.SECONDS);
client.writeTimeout(60, TimeUnit.SECONDS);
client.connectTimeout(60, TimeUnit.SECONDS);
client.addInterceptor(interceptor);
client.addInterceptor(new Interceptor() {
#Override
public okhttp3.Response intercept(Chain chain) throws IOException {
Request request = chain.request();
return chain.proceed(request);
}
});
retrofit = new Retrofit.Builder()
.baseUrl(BASE_URL)
.client(client.build())
.addConverterFactory(GsonConverterFactory.create())
.build();
return retrofit;
}
}
make interface for api calling.
public interface ApiInterface {
#GET("leave_dtls.php")
Call<ResponseData> getData();
}
make pojo class for response.
public class ResponseDataItem{
#SerializedName("Status")
private String status;
#SerializedName("uid")
private String uid;
#SerializedName("reason")
private String reason;
#SerializedName("ApprovedDate")
private String approvedDate;
#SerializedName("Remarks")
private String remarks;
#SerializedName("ApprovedBy")
private String approvedBy;
#SerializedName("id")
private String id;
#SerializedName("type")
private String type;
#SerializedName("EndDate")
private String endDate;
#SerializedName("SataDate")
private String sataDate;
public void setStatus(String status){
this.status = status;
}
public String getStatus(){
return status;
}
public void setUid(String uid){
this.uid = uid;
}
public String getUid(){
return uid;
}
public void setReason(String reason){
this.reason = reason;
}
public String getReason(){
return reason;
}
public void setApprovedDate(String approvedDate){
this.approvedDate = approvedDate;
}
public String getApprovedDate(){
return approvedDate;
}
public void setRemarks(String remarks){
this.remarks = remarks;
}
public String getRemarks(){
return remarks;
}
public void setApprovedBy(String approvedBy){
this.approvedBy = approvedBy;
}
public String getApprovedBy(){
return approvedBy;
}
public void setId(String id){
this.id = id;
}
public String getId(){
return id;
}
public void setType(String type){
this.type = type;
}
public String getType(){
return type;
}
public void setEndDate(String endDate){
this.endDate = endDate;
}
public String getEndDate(){
return endDate;
}
public void setSataDate(String sataDate){
this.sataDate = sataDate;
}
public String getSataDate(){
return sataDate;
}
}
final response..
public class ResponseData {
#SerializedName("response_data")
private List<ResponseDataItem> responseData;
#SerializedName("status")
private int status;
public void setResponseData(List<ResponseDataItem> responseData){
this.responseData = responseData;
}
public List<ResponseDataItem> getResponseData(){
return responseData;
}
public void setStatus(int status){
this.status = status;
}
public int getStatus(){
return status;
}
}
called api into fragment or activity like this way..
ApiInterface apiInterface = ApiClient.getInstance().getClient().create(ApiInterface.class);
Call<ResponseData> responseDataCall=apiInterface.getData();
responseDataCall.enqueue(new Callback<ResponseData>() {
#Override
public void onResponse(Call<ResponseData> call, Response<ResponseData> response) {
if (response.isSuccessful() && response.body()!=null && response!=null){
List<ResponseDataItem> data=response.body().getResponseData();
}
}
#Override
public void onFailure(Call<ResponseData> call, Throwable t) {
t.printStackTrace();
}
});

You can use use POJO classes for converting JSON into classes. Use below website to convert JSON to POJO.
http://www.jsonschema2pojo.org
After that you can use Retrofit to call API and get response. Get reference from this site : https://square.github.io/retrofit/
After you convert into classes you can use Gson Methods for conversion.
SomeModelClass responseModel = new Gson().fromJson(response, SomeModelClass.class);
You can use this addConverterFactory(GsonConverterFactory.create()) retrofit method to directly convert response into class model if you don't want to do it manually.
And finally you can Create adapter using ViewHolder Pattern and use that adapter with RecyclerView.

How to fix Expected BEGIN_OBJECT in Retrofit?

In my application i want use Retrofit for get some data from server.
I write below codes but when run application and call api show me below error :
E/socketLogResponse: Err : com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 1 path $
Please see my above codes and help me
API response from server :
{
"status": "ok",
"time": 0.014972925186157227
}
ApiService interface :
#POST("api/log")
Call<SocketPingResponse> getSocketPingLog(#Header("jwt") String jwt, #Body SocketPingBodySendData socketPingBodySendData);
SocketPingResponse class :
public class SocketPingResponse {
#SerializedName("status")
#Expose
private String status;
#SerializedName("time")
#Expose
private Double time;
public String getStatus() {
return status;
}
public void setStatus(String status) {
this.status = status;
}
public Double getTime() {
return time;
}
public void setTime(Double time) {
this.time = time;
}
}
SocketPingBodySendData class :
public class SocketPingBodySendData {
#SerializedName("auction_id")
#Expose
int auction_id;
#SerializedName("data")
#Expose
List<SocketPingEntity> data;
public int getAuction_id() {
return auction_id;
}
public void setAuction_id(int auction_id) {
this.auction_id = auction_id;
}
public List<SocketPingEntity> getData() {
return data;
}
public void setData(List<SocketPingEntity> data) {
this.data = data;
}
}
Api call codes in activity :
pingEntityList.addAll(socketPingDatabase.socketPingDao().getSocketPingEntityList());
SocketPingBodySendData pingBodySendData = new SocketPingBodySendData();
pingBodySendData.setAuction_id(auctionID);
pingBodySendData.setData(pingEntityList);
Toast.makeText(context, ""+pingEntityList.size(), Toast.LENGTH_SHORT).show();
Call<SocketPingResponse> pingResponseCall = apis.getSocketPingLog(jwtToken, pingBodySendData);
pingResponseCall.enqueue(new Callback<SocketPingResponse>() {
#Override
public void onResponse(Call<SocketPingResponse> call, Response<SocketPingResponse> response) {
if (response.body() != null) {
Toast.makeText(context, response.body().getStatus(), Toast.LENGTH_SHORT).show();
if (response.body().getStatus().equals("ok")) {
pingEntityList.clear();
socketPingDatabase.socketPingDao().deleteAll();
}
}
}
#Override
public void onFailure(Call<SocketPingResponse> call, Throwable t) {
Log.e("socketLogResponse", "Err : " + t.toString());
}
});
How can i fix this issue?

You need to add a gsonconverter factory before building your api service interface.
Retrofit retrofit = new Retrofit.Builder()
.baseUrl(BASE_URL)
.addConverterFactory(GsonConverterFactory.create())
.build();
retrofit.create(apiservice.class)

Retrofit/Jackson error on deserializing

i'm trying to get a JSON from my web service and deserialize to my class UserSync, but i'm getting the following error:
Can not instantiate value of type [simple type, class com.example.breno.teste.model.User] from String value (''); no single-String constructor/factory method
at [Source: okhttp3.ResponseBody$BomAwareReader#fbf814f; line: 1, column: 86] (through reference chain: com.example.breno.teste.dto.UserSync["user"])
I've read some posts saying that i need to declare my User class static in UserSync, but when i do that, jackson can't find any user property, even with JsonDescription. Another posts say that i may need to declare a default constructor, so i did.
Here is the UserSync class:
#JsonIgnoreProperties(ignoreUnknown = true)
public class UserSync {
#JsonProperty("status")
private String Status;
#JsonProperty("currentDate")
private String CurrentDate;
#JsonProperty("message")
private String Message;
#JsonProperty("user")
private static User NewUser;
public UserSync() {
}
public String getStatus() {
return Status;
}
public String getCurrentDate() {
return CurrentDate;
}
public String getMessage() {
return Message;
}
public static User getNewUser() {
return NewUser;
}
The User class:
public class User implements Serializable {
#JsonProperty("userKey")
private UUID UserKey;
#JsonProperty("userPassword")
private String UserPassword;
#JsonProperty("userGroupKey")
private UUID UserGroupKey;
#JsonProperty("signInDate")
private String SignInDate;
#JsonProperty("active")
private boolean Active;
#JsonProperty("profilePicturePath")
private String ProfilePic;
#JsonProperty("completeName")
private String UserCompleteName;
#JsonProperty("email")
private String UserEmail;
#JsonProperty("isLogged")
private boolean IsLogged;
public User() {
}
public boolean getIsLogged() {
return IsLogged;
}
public void setIsLogged(boolean isLogged) {
IsLogged = isLogged;
}
public String getUserEmail() {
return UserEmail;
}
public void setUserEmail(String userEmail) {
UserEmail = userEmail;
}
public UUID getUserKey() {
return UserKey;
}
public void setUserKey(UUID userKey) {
UserKey = userKey;
}
public String getUserPassword() {
return UserPassword;
}
public void setUserPassword(String userPassword) {
UserPassword = userPassword;
}
public UUID getUserGroupKey() {
return UserGroupKey;
}
public void setUserGroupKey(UUID userGroupKey) {
UserGroupKey = userGroupKey;
}
public String getSignInDate() {
return SignInDate;
}
public void setSignInDate(String signInDate) {
SignInDate = signInDate;
}
public boolean getActive() {
return Active;
}
public void setActive(boolean active) {
Active = active;
}
public String getProfilePic() {
return ProfilePic;
}
public void setProfilePic(String profilePic) {
ProfilePic = profilePic;
}
public String getUserCompleteName() {
return UserCompleteName;
}
public void setUserCompleteName(String userCompleteName) {
UserCompleteName = userCompleteName;
}
}
My service class (Using now the postNewUser):
public interface UserService {
#GET("Login/LoginUser?")
Call<UserSync> login(#Query("email") String email, #Query("password") String password);
//region NewUser Services
#GET("Login/VerifyNewUser?")
Call<UserSync> validateNewUser(#Query("email") String email);
#POST("Login/PostNewUser")
Call<UserSync> postNewUser(#Body User user);
//endregion
}
And finally, the JSON:
{
"status": "OK",
"currentDate": "20/07/2017 11:59:02",
"message": "teste",
"user": {
"userKey": "8e2f0d2d-3522-472d-be1d-28791367f4ee",
"email": "teste_teste#hotmail.com",
"userPassword": "123456",
"profilePicturePath": "teste",
"completeName": "Jorge",
"userGroupKey": null,
"signInDate": "2017-07-07T16:26:06.097",
"active": true,
"isLogged": true
}
}
Can someone help me, please?
EDIT 1 - Here is the method that i'm using to do the retrofit call:
public void register(User user) {
Call<UserSync> postCall = new RetrofitInitializator().getUserService().postNewUser(user);
postCall.enqueue(getRegisterCallback());
}
#NonNull
private Callback<UserSync> getRegisterCallback() {
return new Callback<UserSync>() {
#Override
public void onResponse(Call<UserSync> call, Response<UserSync> response) {
User user = response.body().getNewUser();
}
#Override
public void onFailure(Call<UserSync> call, Throwable t) {
Log.e("Register - onFailure", t.getMessage());
}
};
}
EDIT 2 - The retrofitInicializator class:
public class RetrofitInitializator {
private final Retrofit retrofit;
public RetrofitInitializator() {
HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
OkHttpClient.Builder builder = new OkHttpClient
.Builder();
builder.addInterceptor(interceptor);
retrofit = new Retrofit.Builder()
.baseUrl("http://192.168.15.6:7071/api/")
.addConverterFactory(JacksonConverterFactory.create())
.client(builder.build())
.build();
}
public UserService getUserService() {
return retrofit.create(UserService.class);
}
}

I managed to resolve my problem switching the type User to JsonNode and doing the convertion after this.
#JsonProperty("status")
private String Status;
#JsonProperty("currentDate")
private String CurrentDate;
#JsonProperty("message")
private String Message;
#JsonProperty("user")
private JsonNode NewUser;
and the convertion:
private User getUserFromUserAsync(UserSync userSync) throws JsonProcessingException {
ObjectMapper mapper = new ObjectMapper();
return mapper.treeToValue(userSync.getNewUser(), User.class);
}

Failed to bind JSON response to GSON annotated POJO

I intended to bind a JSON string to POJO annotated with GSON, the JSON response is from the ReSTFUL service to list all countries: http://services.groupkt.com/country/get/all
the response is fine, which looks like
{
"RestResponse": {
"messages": [
"More webservices are available at http://www.groupkt.com/post/f2129b88/services.htm",
"Total [249] records found."
],
"result": [
{
"name": "Afghanistan",
"alpha2_code": "AF",
"alpha3_code": "AFG"
},
{
"name": "Åland Islands",
"alpha2_code": "AX",
"alpha3_code": "ALA"
},
...
]
}
}
The POJO Country and its associated classes were created using this tool:http://www.jsonschema2pojo.org/ and they look like:
Country.java
public class Country implements Serializable{
#SerializedName("RestResponse")
#Expose
private RestResponse restResponse;
public RestResponse getRestResponse() {
return restResponse;
}
public void setRestResponse(RestResponse restResponse) {
this.restResponse = restResponse;
}
}
RestResponse.java
public class RestResponse implements Serializable{
#SerializedName("messages")
#Expose
private List<String> messages = null;
#SerializedName("result")
#Expose
private List<Result> result = null;
public List<String> getMessages() {
return messages;
}
public void setMessages(List<String> messages) {
this.messages = messages;
}
public List<Result> getResult() {
return result;
}
public void setResult(List<Result> result) {
this.result = result;
}
}
Result.java
public class Result implements Serializable{
#SerializedName("name")
#Expose
private String name;
#SerializedName("alpha2_code")
#Expose
private String alpha2Code;
#SerializedName("alpha3_code")
#Expose
private String alpha3Code;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAlpha2Code() {
return alpha2Code;
}
public void setAlpha2Code(String alpha2Code) {
this.alpha2Code = alpha2Code;
}
public String getAlpha3Code() {
return alpha3Code;
}
public void setAlpha3Code(String alpha3Code) {
this.alpha3Code = alpha3Code;
}
}
The code below however failed to bind the JSON string to the GSON annotated POJOs - the restResponse is NULL, so are the message and result. Can anyone tell me what went wrong?
#SpringBootApplication
public class App implements CommandLineRunner
{
private static Logger log = LoggerFactory.getLogger(App.class);
/*
* boiler plate code
* */
public static void main( String[] args )
{
SpringApplication.run(App.class, args);
}
/*
* Configuration section
* */
#Bean
public RestTemplate newRestTemplate(){
RestTemplate rt = new RestTemplate();
return rt;
}
/*
* public APIs section
* */
#Autowired
private RestTemplate restTemplate;
#Override
public void run(String... args) throws Exception {
String url = "http://services.groupkt.com/country/get/all";
ResponseEntity<String> res = restTemplate.getForEntity(url, String.class);
log.info("{}",res.getBody());
GsonHttpMessageConverter msgConverter = new GsonHttpMessageConverter();
Gson gson = new GsonBuilder().setPrettyPrinting().create();
msgConverter.setGson(gson);
restTemplate.getMessageConverters().add(msgConverter);
Country country = restTemplate.getForObject(url, Country.class);
RestResponse resp = country.getRestResponse();
List<Result> l = resp.getResult();
for(Result r : l){
log.info("country name = {}",r.getName());
}
}
}

I managed to update the code like below and it works now:
RestTemplate rt = new RestTemplate();
String url = "http://services.groupkt.com/country/get/all";
ResponseEntity<String> resp = rt.getForEntity(url, String.class);
assertEquals(resp.getStatusCode(), HttpStatus.OK);
Gson gson = new GsonBuilder().create();
Country c = gson.fromJson(resp.getBody(), Country.class);
still don't know why the code below didn't work, though.
Country country = restTemplate.getForObject(url, Country.class);