Develop Reference

How to parse nested json using retrofit in expandable Listview? [duplicate]

Our team decide to use Retrofit 2.0 and I'm doing some initial research on this library. As stated in the title, I want parse some nested JSON objects via Retrofit 2.0 in our Android app.
For example, here is a nested JSON object with the format:
{
"title": "Recent Uploads tagged android",
"link": "https://www.flickr.com/photos/tags/android/",
"description": "",
"modified": "2015-10-05T05:30:01Z",
"generator": "https://www.flickr.com/",
"items": [
{
"title": ...
"link": ...
"media": {"m":"This is the value I want to get:)"}
"description": ...
"published": ...
"author": ...
"author_id": ...
"tags": ...
},
{...},
...
]
}
I'm interested in the JSON objects inside items array. I notice there are some posts about parsing nested JSON objects via Retrofit 1.X, but the latest Retrofit 2.0 APIs has changed a lot, which is confusing when adapting them to the new APIs.
Two possible solutions come into my mind:
Write my own JSON converter factory which extends Converter.Factory.
Return the raw response in a String type and parse it by myself. But it's not easy to get the raw response from Retrofit 2.0 according to my initial research. Retrofit 2.0 seems to insist in converting the response to something before pass it to me and Retrofit doesn't provide its own StringConverter. (I might be wrong~)
Update: We can actually get the raw response by setting JSONElement as the pojo for the HTTP API interface and use GSONConverter provided by Retrofit as the converter.

Assuming your complete JSON looks like
{
"title": "Recent Uploads tagged android",
"link": "https://www.flickr.com/photos/tags/android/",
"description": "",
"modified": "2015-10-05T05:30:01Z",
"generator": "https://www.flickr.com/",
"items": [
{
"member1": "memeber value",
"member2": "member value"
},
{
"member1": "memeber value",
"member2": "member value"
}
]
}
So Pojo classes would be
public class MainPojo {
private String title;
private String description;
private String link;
private String generator;
private String modified;
private ArrayList<Items> items;
// Getters setters
}
public class Items {
private String member2;
private String member1;
// Getters setters
}
Note : This is similar solution for your JSON. Members of Items.java can be changed if JSON has other keys.
Update for Pojo as new JSON
public class Items {
private String tags;
private String author;
private String title;
private String description;
private String link;
private String author_id;
private String published;
private Media media;
// Getters and Setters
}
public class Media {
private String m;
// Getters and Setters
}

Following code will help to get nested json object and array
for example: json
{
"similar_product":[
{ .....
}
],
"options":{
"Blouse Length":[
{ "value_id":"696556",
}
first we need to create model class, model class items names are same in json item we can use #SerializedName("for exact json name")
public class Product {
public Options options;
public void setOptions(Options options) {
this.options = options;
}
public Options getOptions() {
return options;
}
// length...
public class Options
{
#SerializedName("Blouse Length")
private ArrayList<BlouseLength> blouseLengths;
public void setBlouseLengths(ArrayList<BlouseLength> blouseLengths) {
this.blouseLengths = blouseLengths;
}
public ArrayList<BlouseLength> getBlouseLengths() {
return blouseLengths;
}
}
public class BlouseLength {
String value_id;
public void setValue_id(String value_id) {
this.value_id = value_id;
}
public String getValue_id() {
return value_id;
}
}
}
create Interface for retrofit to get json item in url
// don't need to put values of id in retrofit
ex:: "/api-mobile_.php?method=getProductById&pid="
just pass url parameter in query it automatically fetch the url
for example:
public interface Retrofit_Api {
#FormUrlEncoded
#GET("/api-mobile_.php?method=getProductById")
Call<Product> responseproduct(#Query("pid") String pid);
}
In your Main class
String pid=editid.getText().toString();
final Retrofit adapter = new Retrofit.Builder()
.baseUrl(Product_url)
.addConverterFactory(GsonConverterFactory.create())
.build();
//Creating an object of our api interface
Retrofit_Api api = adapter.create(Retrofit_Api.class);
Call<Product> call = api.responseproduct(pid);
call.enqueue(new Callback<Product>() {
#Override
public void onResponse(Call<Product> call, Response<Product> response) {
ArrayList<Product.BlouseLength> p= new ArrayList(response.body().getOptions().getBlouseLengths());
Editadapter editadapter=new Editadapter(MainActivity.this,p);
recyclerView.setAdapter(editadapter);
}
#Override
public void onFailure(Call<Product> call, Throwable t) {
Log.d("Error", t.getMessage());
}
});
}

Use Gson easy parsing for your models https://github.com/google/gson
My Helper Methods :
public String toJson(Object object) {
return gson.toJson(object);
}
public <T> T fromJson(String json, Class<T> classOfT) {
return gson.fromJson(json, classOfT);
}
public <T> T fromJson(JsonElement jsonElement, Class<T> classOfT) {
return gson.fromJson(jsonElement, classOfT);
}

have you tried volley? ...i prefer it over retrofit now that is a google product.I have working example and if u dont mind i can show you.
http://www.androidhive.info/2014/09/android-json-parsing-using-volley/

I forgot add #SerializedName and #Expose annotations for inner Class objects and after add these annotations problem solved. Like this:
JSON:
{"Id": 1,}
and Class member:
#SerializedName("Id")
#Expose
private int id;

How to write a Pojo using a dynamic key inside JSONarray

I don't even know if this is a valid question but I am having a hard time converting the API result to POJO since some key are dynamic.
{
"data": [{
"something_edit": true
},
{
"test_null": false
}
],
"success": true
}
As you can see the key inside data are dynamic. I tried using jsonschema2pojo or other converter but it is declaring a named variable which is not a good result. BTW I am using retrofit and GSON library
EDIT:
So here is the flow, so the keys are the ones I asked on the API. So for Example I asked something_edit1, something_edit2 and something_edit3. The data result will be.
{
"data": [{
"something_edit1": true
}, {
"something_edit2": false
},
{
"something_edit3": false
}
],
"success": true
}

You can use Json Object or Generics for your condition.
Using Json Object you can check, if key is exist in your json.
if(yourJsonObject.hasOwnProperty('key_name')){
// do your work here
}
Using Generic you have to check, if your Pojo have instance of the
Pojo.
if(YourMainPOJO instanceOf YourChildPojo){
// do your work here
}
Try to view only Generic part in this link.

It's hard to determine or you have to declare all the possible fields in your POJO or write your own json parser extending the Gson Parser or use a JsonElement which can be converted into json array, object and primitive, based on that result you can convert back to some specific pojo.
/**
* this will convert the whole json into map which you can use to determine the json elements
*
* #param json
*/
private void getModelFromJson(JsonObject json) {
Gson gson = new Gson();
Map<String, JsonElement> jsonElementMap = gson.fromJson(json.toString(), new TypeToken<Map<String, JsonElement>>() {
}.getType());
for (Map.Entry<String, JsonElement> jsonElementEntry : jsonElementMap.entrySet()) {
if (jsonElementEntry.getValue().isJsonPrimitive()) {
//json primitives are data types, do something
//get json boolean
//you can here also check if json element has some json object or json array or primitives based on that
//you can convert this to something else after comparison
if (true) {
InterestModelResponse response = gson.fromJson(jsonElementEntry.getValue().getAsJsonObject().toString(), InterestModelResponse.class);
//use your dynamic converted model
}
} else {
//do something else
}
}
}

2 Years ago we did a project in which we had to handle notifications data with different type of objects in same array we handle that while using retrofit
this is our retrofit Creator class
class Creator {
public static FullTeamService newFullTeamService() {
final HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
final OkHttpClient client = new OkHttpClient.Builder()
.addInterceptor(interceptor)
.build();
final Retrofit retrofit = new Retrofit.Builder()
.baseUrl(FullTeamService.HOST)
.client(client)
.addConverterFactory(GsonConverterFactory.create(GsonUtils.get()))
.addCallAdapterFactory(RxJavaCallAdapterFactory.create())
.build();
return retrofit.create(FullTeamService.class);
}
}
and GsonUtils.java is:
public class GsonUtils {
private static final Gson sGson = new GsonBuilder()
.setDateFormat("yyyy-MM-dd'T'HH:mm:ss")
.registerTypeAdapter(NotificationObject.class, new NotificationDeserializer())
.create();
private GsonUtils() {}
public static Gson get() {
return sGson;
}
}
NotificationObject is something like:
public class NotificationObject {
#SerializedName("ID")
#Expose
private long ID;
#SerializedName("type")
#Expose
private Type type;
#SerializedName("DataObject")
#Expose
private NotificationDataObject dataObject;
public void setDataObject(NotificationDataObject newsFields) {
dataObject = newsFields;
}
#SuppressWarnings("unchecked")
public <T> T getDataObject() {
return (T) dataObject;
}
public enum Type {
#SerializedName("0")
CHAT_MESSAGE,
#SerializedName("10")
GAME_APPLICATION,
#SerializedName("20")
GAME_APPLICATION_RESPONSE,
#SerializedName("30")
GAME_INVITE....
}
}
NotificationDataObject as new class is like:
public class NotificationDataObject {}
and finally NotificationDeserializer is like:
public class NotificationDeserializer implements JsonDeserializer<NotificationObject> {
#Override
public NotificationObject deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
final JsonObject itemBean = json.getAsJsonObject();
final NotificationObject object = GsonUtils.getSimpleGson().fromJson(itemBean, NotificationObject.class);
switch (object.getType()) {
case CHAT_MESSAGE:
break;
case GAME_APPLICATION:
object.setDataObject(GsonUtils.get().fromJson(itemBean.get("DataObject").getAsJsonObject(),
GameApplicationNotification.class));
break;
case GAME_APPLICATION_RESPONSE:
object.setDataObject(GsonUtils.get().fromJson(itemBean.get("DataObject").getAsJsonObject(),
GameApplicationResponseNotification.class));
break;
case GAME_INVITE:
object.setDataObject(GsonUtils.get().fromJson(itemBean.get("DataObject").getAsJsonObject(),
GameInviteNotification.class));
break;
}
return object;
}
}
Happy coding ...!
any query will be appreciated...

Android Retrofit and GSON: JSON response returns object or string as property value

The JSON data returned from the server can either return an object, or if that object is null, it returns an empty string ("").
My problem is that my DTO expects an object, but it sees a string and crashes.
PersonDTO
data class PersonDto(
#SerializedName("firstName") val first: String,
#SerializedName("lastName") val last: String,
#SerializedName("favorites") val favorites: FavoriteDto,
)
FavoriteDto
class FavoriteDto(
#SerializedName("color") val color: String,
#SerializedName("number") val number: Int
)
Different responses from server
"person" : {
"firstName": "Steve",
"lastName" : "Johnson",
"favorites" : {
"color": "Purple",
"number": 25
}
}
...
"person" : {
"firstName": "Steve",
"lastName" : "Johnson",
"favorites" : ""
}
I've heard that I might need a custom GSON deserializer, but I've never done anything with GSON other than the out of the box stuff - so I was hoping for a nudge in the right direction.
Thanks!

Easiest hack is that you can add extra fields in the class with the same serialised name but with a String data type. Like this -
data class PersonDto(
#SerializedName("firstName") val first: String,
#SerializedName("lastName") val last: String,
#SerializedName("favorites") val favorites: FavoriteDto,
#SerializedName("favorites") val favoritesStr: String,
)
As there is nothing in Gson as "Required" field, you'll just get a null in your deserialized object if something is missing in the JSON. So, if there is an empty string the FavoriteDto object will be null and not null otherwise.
EDIT
I'm adding some Java code that I have written earlier. This might help:
public class PersonDto {
private FavoriteDto favorites;
private String favoritesStr;
public FavoriteDto getResponseDataObject() {
return favorites;
}
public void setResponseDataObject(FavoriteDto favorites) {
this.favorites = favorites;
}
public String getResponseDataString() {
return favoritesStr;
}
public void setResponseDataString(String favoritesStr) {
this.favoritesStr = favoritesStr;
}
Defining the Deserializar:
public static class ArrayObjectDualityDeserializer implements JsonDeserializer<PersonDto> {
public PersonDto deserialize(JsonElement json, Type typeOfT,
JsonDeserializationContext context) throws JsonParseException {
PersonDto response = new PersonDto();
JsonObject object = json.getAsJsonObject();
if(object.get("favorites").isJsonArray()) {
} else if(object.get("favorites").isJsonObject()) {
try {
FavoriteDto dtoObject = gson.fromJson(object.get("favorites"), FavoriteDto.class);
response.setResponseDataObject(dtoObject);
} catch (JsonSyntaxException e) {
DebugLogger.e("Error " + e);
}
} else if (object.get("favorites").isJsonNull()) {
} else {
response.setResponseDataString(object.get("favorites").getAsString());
}
}
}
And:
public static Gson gson = new GsonBuilder()
.registerTypeAdapter(PersonDto.class, new ArrayObjectDualityDeserializer())
.create();
Lastly:
private static Retrofit retrofit = null;
private static OkHttpClient.Builder httpClient = null;
private static OkHttpClient session_client = null;
httpClient = new OkHttpClient.Builder();
httpClient.addInterceptor(new SessionOkHttpInterceptor());
session_client = httpClient.build();
retrofit = new Retrofit.Builder()
.baseUrl(BASE_URL)
.client(session_client)
.addConverterFactory(GsonConverterFactory.create(gson))
.build();

The answer of #Subrato M. is partially correct. In order to work, you should remove #SerializedName("favorites") annotation from both fields in order to work. In this case, Gson won't throw an error when deserialize multiple json fields named favorites because you don't have any field annotated with that name (also don't name fileds the same as expected field name beucase Gson will try to deserialize). Use the custom deserializer to check if is an object or a string.

Nowadays isn't necessary the #Subrato M's hack, you don't get the right json cause you are missing the data keyword before class FavoriteDto and that is why doesn't exists the get and set methods

Generic Type Gson deserializer

I have an Api which the api looks like this:
If the response is ok the structure will begin with data keyword for example:
{
"data": {
"name": "Rogelio Volkman",
"address": "27299 Will Bridge Suite 058\nWest Reubenhaven, MI 00736",
"lat": 54.65,
"lng": 111.75,
"phone": "+26(4)5015498663"
}
}
And if response is not Ok(status is not 200) response will not container data keyword so response will look like:
{
"message": "404 Not Found",
"status_code": 404
}
Since this structure is a common structure for all models I intended to create a Generic Deserializer for all models.
This looked like:
public class DataObjectDeserializer implements JsonDeserializer<Object> {
#Override
public Objectdeserialize(JsonElement je, Type type, JsonDeserializationContext jdc)
throws JsonParseException {
// Get the "data" element from the parsed JSON
JsonElement data = je.getAsJsonObject().get("data");
// Deserialize it. You use a new instance of Gson to avoid infinite recursion
// to this deserializer
return new Gson().fromJson(data, Object.class);
}
}
then registered it as typeAdapter Gson gson = new GsonBuilder().registerTypeHierarchyAdapter(Object.class, new DataObjectDeserializer()).create();
Since every object is an instance of Object I supposed this would work (deserialize my Museum model) but it didn't.
In my second attempt I created an abstract class called DataObjectModel and class Museum extended DataObjectModel. then created anoteher deserailizer like:
public class DataObjectDeserializer implements JsonDeserializer {
#Override
public DataObjectModel deserialize(JsonElement je, Type type, JsonDeserializationContext jdc)
throws JsonParseException {
// Get the "data" element from the parsed JSON
JsonElement data = je.getAsJsonObject().get("data");
// Deserialize it. You use a new instance of Gson to avoid infinite recursion
// to this deserializer
return new Gson().fromJson(data, DataObjectModel.class);
}
}
And registered it with Gson like Gson gson = new GsonBuilder().registerTypeHierarchyAdapter(DataObjectModel.class, new DataObjectDeserializer()).create();. But this didn't deserialize Museum model either.
The question is: how can I create a deserializer for parent class which would deserialize child class as well (as my second approach) Or How can I create a generic class with Gson so that every tyoe that is wrapped aroung data can be used with it like:
public class DataObjectDeserializer implements JsonDeserializer {
#Override
public T deserialize(JsonElement je, Type type, JsonDeserializationContext jdc)
throws JsonParseException {
// Get the "data" element from the parsed JSON
JsonElement data = je.getAsJsonObject().get("data");
// Deserialize it. You use a new instance of Gson to avoid infinite recursion
// to this deserializer
return new Gson().fromJson(data, /* This part not working due to type erasing in java*/ T.calss);
}
}

If you create your response and data structure like this
private class Data {
#SerializedName("name")
private String name;
#SerializedName("address")
private String address;
#SerializedName("lat")
private String lat;
#SerializedName("lng")
private String lng;
#SerializedName("phone")
private String phone;
}
private class Response {
#SerializedName("message")
private String message;
#SerializedName("status_code")
private int statusCode;
#SerializedName("data")
private Data data;
}
you can then do
Response response = new Gson().fromJson(json, Response.class);
if(response.statusCode == 0) {
//everything ok, do something with response.data
} else {
//display response.message, data will be null
}

How can Retrofit 2.0 parse nested JSON object?

Our team decide to use Retrofit 2.0 and I'm doing some initial research on this library. As stated in the title, I want parse some nested JSON objects via Retrofit 2.0 in our Android app.
For example, here is a nested JSON object with the format:
{
"title": "Recent Uploads tagged android",
"link": "https://www.flickr.com/photos/tags/android/",
"description": "",
"modified": "2015-10-05T05:30:01Z",
"generator": "https://www.flickr.com/",
"items": [
{
"title": ...
"link": ...
"media": {"m":"This is the value I want to get:)"}
"description": ...
"published": ...
"author": ...
"author_id": ...
"tags": ...
},
{...},
...
]
}
I'm interested in the JSON objects inside items array. I notice there are some posts about parsing nested JSON objects via Retrofit 1.X, but the latest Retrofit 2.0 APIs has changed a lot, which is confusing when adapting them to the new APIs.
Two possible solutions come into my mind:
Write my own JSON converter factory which extends Converter.Factory.
Return the raw response in a String type and parse it by myself. But it's not easy to get the raw response from Retrofit 2.0 according to my initial research. Retrofit 2.0 seems to insist in converting the response to something before pass it to me and Retrofit doesn't provide its own StringConverter. (I might be wrong~)
Update: We can actually get the raw response by setting JSONElement as the pojo for the HTTP API interface and use GSONConverter provided by Retrofit as the converter.

Assuming your complete JSON looks like
{
"title": "Recent Uploads tagged android",
"link": "https://www.flickr.com/photos/tags/android/",
"description": "",
"modified": "2015-10-05T05:30:01Z",
"generator": "https://www.flickr.com/",
"items": [
{
"member1": "memeber value",
"member2": "member value"
},
{
"member1": "memeber value",
"member2": "member value"
}
]
}
So Pojo classes would be
public class MainPojo {
private String title;
private String description;
private String link;
private String generator;
private String modified;
private ArrayList<Items> items;
// Getters setters
}
public class Items {
private String member2;
private String member1;
// Getters setters
}
Note : This is similar solution for your JSON. Members of Items.java can be changed if JSON has other keys.
Update for Pojo as new JSON
public class Items {
private String tags;
private String author;
private String title;
private String description;
private String link;
private String author_id;
private String published;
private Media media;
// Getters and Setters
}
public class Media {
private String m;
// Getters and Setters
}

Following code will help to get nested json object and array
for example: json
{
"similar_product":[
{ .....
}
],
"options":{
"Blouse Length":[
{ "value_id":"696556",
}
first we need to create model class, model class items names are same in json item we can use #SerializedName("for exact json name")
public class Product {
public Options options;
public void setOptions(Options options) {
this.options = options;
}
public Options getOptions() {
return options;
}
// length...
public class Options
{
#SerializedName("Blouse Length")
private ArrayList<BlouseLength> blouseLengths;
public void setBlouseLengths(ArrayList<BlouseLength> blouseLengths) {
this.blouseLengths = blouseLengths;
}
public ArrayList<BlouseLength> getBlouseLengths() {
return blouseLengths;
}
}
public class BlouseLength {
String value_id;
public void setValue_id(String value_id) {
this.value_id = value_id;
}
public String getValue_id() {
return value_id;
}
}
}
create Interface for retrofit to get json item in url
// don't need to put values of id in retrofit
ex:: "/api-mobile_.php?method=getProductById&pid="
just pass url parameter in query it automatically fetch the url
for example:
public interface Retrofit_Api {
#FormUrlEncoded
#GET("/api-mobile_.php?method=getProductById")
Call<Product> responseproduct(#Query("pid") String pid);
}
In your Main class
String pid=editid.getText().toString();
final Retrofit adapter = new Retrofit.Builder()
.baseUrl(Product_url)
.addConverterFactory(GsonConverterFactory.create())
.build();
//Creating an object of our api interface
Retrofit_Api api = adapter.create(Retrofit_Api.class);
Call<Product> call = api.responseproduct(pid);
call.enqueue(new Callback<Product>() {
#Override
public void onResponse(Call<Product> call, Response<Product> response) {
ArrayList<Product.BlouseLength> p= new ArrayList(response.body().getOptions().getBlouseLengths());
Editadapter editadapter=new Editadapter(MainActivity.this,p);
recyclerView.setAdapter(editadapter);
}
#Override
public void onFailure(Call<Product> call, Throwable t) {
Log.d("Error", t.getMessage());
}
});
}

Use Gson easy parsing for your models https://github.com/google/gson
My Helper Methods :
public String toJson(Object object) {
return gson.toJson(object);
}
public <T> T fromJson(String json, Class<T> classOfT) {
return gson.fromJson(json, classOfT);
}
public <T> T fromJson(JsonElement jsonElement, Class<T> classOfT) {
return gson.fromJson(jsonElement, classOfT);
}

have you tried volley? ...i prefer it over retrofit now that is a google product.I have working example and if u dont mind i can show you.
http://www.androidhive.info/2014/09/android-json-parsing-using-volley/

I forgot add #SerializedName and #Expose annotations for inner Class objects and after add these annotations problem solved. Like this:
JSON:
{"Id": 1,}
and Class member:
#SerializedName("Id")
#Expose
private int id;