I'm willing to try the new Room Library from Android and I met the below error:
Error:(19, 29) error: Cannot figure out how to save this field into
database. You can consider adding a type converter for it.
This error refers to the following class member:
private HashSet<String> fruits;
I have the following class:
#Entity(tableName = "SchoolLunches")
public class SchoolLunch {
#PrimaryKey(autoGenerate = true)
private int lunchId;
private boolean isFresh;
private boolean containsMeat;
private HashSet<String> fruits;
public int getLunchId() {
return lunchId;
}
public void setLunchId(int lunchId) {
this.lunchId = lunchId;
}
public boolean isFresh() {
return isFresh;
}
public void setFresh(boolean fresh) {
isFresh = fresh;
}
public boolean isContainsMeat() {
return containsMeat;
}
public void setContainsMeat(boolean containsMeat) {
this.containsMeat = containsMeat;
}
public HashSet<String> getFruits() {
return fruits;
}
public void setFruits(HashSet<String> fruits) {
this.fruits = fruits;
}
Also, there is a relative DAO class:
#Dao
public interface SchoolLunchDAO {
#Query("SELECT * FROM SchoolLunches")
List<SchoolLunch> getAll();
#Insert
void insertAll(SchoolLunch... schoolLunches);
#Query("DELETE FROM SchoolLunches")
void deleteAll();
}
Since I'm trying to be a very good developer, I wrote a unit test as follows:
#Test
public void singleEntityTest() {
HashSet<String> fruitSet = new HashSet<>();
fruitSet.add("Apple");
fruitSet.add("Orange");
SchoolLunch schoolLunch = new SchoolLunch();
schoolLunch.setContainsMeat(false);
schoolLunch.setFresh(true);
schoolLunch.setFruits(fruitSet);
schoolLunchDAO.insertAll(schoolLunch);
List<SchoolLunch> schoolLunches = schoolLunchDAO.getAll();
assertEquals(schoolLunches.size(), 1);
SchoolLunch extractedSchoolLunch = schoolLunches.get(0);
assertEquals(false, extractedSchoolLunch.isContainsMeat());
assertEquals(true, extractedSchoolLunch.isFresh());
assertEquals(2, extractedSchoolLunch.getFruits().size());
}
What should I do here?
What should I do here?
You could create a type converter, as suggested by the error message. Room does not know how to persist a HashSet<String>, or a Restaurant, or other arbitrary objects.
Step #1: Decide what basic type you want to convert your HashSet<String> into (e.g., a String)
Step #2: Write a class with public static type conversion methods, annotated with #TypeConverter, to do the conversion (e.g., HashSet<String> to String, String to HashSet<String>), in some safe fashion (e.g., use Gson, formatting your String as JSON)
Step #3: Add a #TypeConverters annotation to your RoomDatabase or other scope, to teach Room about your #TypeConverter methods
For example, here are a pair of type converter methods for converting a Set<String> to/from a regular String, using JSON as the format of the String.
#TypeConverter
public static String fromStringSet(Set<String> strings) {
if (strings==null) {
return(null);
}
StringWriter result=new StringWriter();
JsonWriter json=new JsonWriter(result);
try {
json.beginArray();
for (String s : strings) {
json.value(s);
}
json.endArray();
json.close();
}
catch (IOException e) {
Log.e(TAG, "Exception creating JSON", e);
}
return(result.toString());
}
#TypeConverter
public static Set<String> toStringSet(String strings) {
if (strings==null) {
return(null);
}
StringReader reader=new StringReader(strings);
JsonReader json=new JsonReader(reader);
HashSet<String> result=new HashSet<>();
try {
json.beginArray();
while (json.hasNext()) {
result.add(json.nextString());
}
json.endArray();
}
catch (IOException e) {
Log.e(TAG, "Exception parsing JSON", e);
}
return(result);
}
I created the following class and now it works. Thank you, CommonsWare!
public class Converters {
private static final String SEPARATOR = ",";
#TypeConverter
public static HashSet<String> fromString(String valueAsString) {
HashSet<String> hashSet = new HashSet<>();
if (valueAsString != null && !valueAsString.isEmpty()) {
String[] values = valueAsString.split(SEPARATOR);
hashSet.addAll(Arrays.asList(values));
}
return hashSet;
}
#TypeConverter
public static String hashSetToString(HashSet<String> hashSet) {
StringBuilder stringBuilder = new StringBuilder();
for (String currentElement : hashSet) {
stringBuilder.append(currentElement);
stringBuilder.append(SEPARATOR);
}
return stringBuilder.toString();
}
}
Related
I need to a simple example for use GraphQl in android .
How can I use from GraphQl in android (tutorial).
In order to use GraphQL (in general), you need two things:
1. A GraphQL server
There are a few ways how you could go about this. Of course, you could simply go and implement one yourself in any server-side language you like.
Other (faster) approaches are to take advantage of existing tooling and generate a GraphQL API using services like graphql-up or create-graphql-server or even services like Graphcool (disclaimer: I work for them).
2. A GraphQL client library
Though this one isn't strictly necessary and you could also simply interact with the GraphQL server through plain HTTP (sending your queries and mutations in the body of POST requests), it is certainly beneficial to use existing tools that take repetitive work like caching or UI integrations off your shoulders. One of the most popular GraphQL clients right now is Apollo, and they're very actively working on a version for Android as well. However, this hasn't been officially released yet. So, you either have to use their existing development version of chose the former approach using plain HTTP for now.
Here is an example of querying GraphQl from Client. In this example I am using Retrofit 2:
// QueryHelper.java
// This line below is the simple format of Gql query
query = "query{me{name, location, majorOfInterest,profilePhoto{url(size: 400) }}}";
//Post the query using Retrofit2
GqlRetrofitClient.getInstance(getContext()).fetchUserDetails(new GqlQueryRequest(queryUserDetails)).enqueue(new Callback<UserDetails>() {
#Override
public void onResponse(Call<UserDetails> call, Response<UserDetails> response) {
//OnResponse do something();
}
#Override
public void onFailure(Call<UserDetails> call, Throwable t) {
Log.d(TAG, "Failed to fetch User details");
}
});
//GqlClient.java
public class GqlRetrofitClient {
public static final String BASE_URL = BuildConfig.DOMAIN;
private static GqlRetrofitClient sInstance;
private GqlRetrofitService mGqlRetrofitService;
Gson gson = new GsonBuilder().create();
private GqlRetrofitClient(final Context context) {
// Network Interceptor for logging
HttpLoggingInterceptor httpLoggingInterceptor = new HttpLoggingInterceptor();
httpLoggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
OkHttpClient okHttpClient = new OkHttpClient.Builder()
.addNetworkInterceptor(new Interceptor() {
#Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request().newBuilder()
.addHeader("X-User-Token", "AUTH_TOKEN")
.addHeader("X-User_Email", "Email")
.addHeader("content-type", "application/json")
.build();
return chain.proceed(request);
}
})
.addInterceptor(httpLoggingInterceptor)
.build();
// Retrofit initialization
final Retrofit retrofit = new Retrofit.Builder()
.baseUrl(BASE_URL)
.addConverterFactory(GsonConverterFactory.create(gson))
.client(okHttpClient)
.build();
mGqlRetrofitService = retrofit.create(GqlRetrofitService.class);
}
// Create an instance of GqlRetrofitClient to create retrofit service
public static GqlRetrofitClient getInstance(Context context){
if(sInstance == null){
sInstance = new GqlRetrofitClient(context.getApplicationContext());
}
return sInstance;
}
// Method call to get User details
public Call<UserDetails> fetchUserDetails(GqlQueryRequest queryUserDetails){
return mGqlRetrofitService.getUserDetails(queryUserDetails);
}
}
//GqlRetrofitService.java
public interface GqlRetrofitService{
#POST("/api/graph.json")
Call<UserDetails> getUserDetails(#Body GqlQueryRequest body);
}
In your manifest to add
<uses-permission android:name="android.permission.INTERNET"/>
Your dependencies
// Kotlin Coroutines
implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.3.4'
//OkHttp
implementation ("com.squareup.okhttp3:okhttp:3.12.12"){
force = true //API 19 support
}
implementation 'com.squareup.okhttp3:logging-interceptor:3.12.12'
//retrofit
implementation "com.squareup.retrofit2:retrofit:2.7.1"
implementation "com.squareup.retrofit2:converter-scalars:$2.7.1"
Also Java 8 compatibility
android {
...
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8
}
kotlinOptions {
jvmTarget = "1.8"
}
}
With the service
import retrofit2.Response
import retrofit2.http.Body
import retrofit2.http.Headers
import retrofit2.http.POST
interface GraphQLService {
#Headers("Content-Type: application/json")
#POST("/")
suspend fun postDynamicQuery(#Body body: String): Response<String>
}
you can create a object
import retrofit2.Retrofit
import retrofit2.converter.scalars.ScalarsConverterFactory
object GraphQLInstance {
private const val BASE_URL: String = "http://192.155.1.55:2000/"
val graphQLService: GraphQLService by lazy {
Retrofit
.Builder()
.baseUrl(BASE_URL)
.addConverterFactory(ScalarsConverterFactory.create())
.build().create(GraphQLService::class.java)
}
}
In the activity you can create this method
private fun post(userId: String){
val retrofit = GraphQLInstance.graphQLService
val paramObject = JSONObject()
paramObject.put("query", "query {users(userid:$userId){username}}")
GlobalScope.launch {
try {
val response = retrofit.postDynamicQuery(paramObject.toString())
Log.e("response", response.body().toString())
}catch (e: java.lang.Exception){
e.printStackTrace()
}
}
}
You can check the example in GitHub and my post
Note: if you need a mutation should be to change this line
paramObject.put("query", "query {users(userid:$userId){username}}")
to
paramObject.put("query", "mutation {users(userid:$userId){username}}")
personally I use Retrofit and I took this Link Credits
and changed some things.
This is the code:
In File "GraphQLConverter.java":
public class GraphQLConverter extends Converter.Factory {
private static final MediaType MEDIA_TYPE = MediaType.parse("application/json; charset=UTF-8");
private GraphQueryProcessor graphProcessor;
private final Gson mGson;
private GraphQLConverter(Context context) {
graphProcessor = new GraphQueryProcessor(context);
mGson = new GsonBuilder()
.enableComplexMapKeySerialization()
.setLenient()
.create();
}
public static GraphQLConverter create(Context context) {
return new GraphQLConverter(context);
}
/** Override Converter.Factory Methods **/
#Override
public Converter<ResponseBody, ?> responseBodyConverter(Type type, Annotation[] annotations, Retrofit retrofit) {
return null;
}
#Override
public Converter<?, RequestBody> requestBodyConverter(Type type, Annotation[] parameterAnnotations, Annotation[] methodAnnotations, Retrofit retrofit) {
if(type == QueryContainerBuilder.class){
return new GraphRequestConverter(methodAnnotations);
} else {
return null;
}
}
/** RequestConverter Class **/
private class GraphRequestConverter implements Converter<QueryContainerBuilder, RequestBody> {
private Annotation[] mAnnotations;
private GraphRequestConverter(Annotation[] annotations) {
mAnnotations = annotations;
}
#Override
public RequestBody convert(#NonNull QueryContainerBuilder containerBuilder) {
QueryContainerBuilder.QueryContainer queryContainer = containerBuilder
.setQuery(graphProcessor.getQuery(mAnnotations))
.build();
return RequestBody.create(MEDIA_TYPE, mGson.toJson(queryContainer).getBytes());
}
}
}
In File "GraphQuery.java":
#Target(ElementType.METHOD)
#Retention(RetentionPolicy.RUNTIME)
public #interface GraphQuery {
String value() default "";
}
In File "GraphQueryProcessor.java":
class GraphQueryProcessor {
private static final String TAG = GraphQueryProcessor.class.getSimpleName();
// GraphQl Constants
private static final String EXT_GRAPHQL = ".graphql";
private static final String ROOT_FOLDER_GRAPHQL = "graphql";
private final Map<String, String> mGraphQueries;
private Context mContext;
GraphQueryProcessor(Context context) {
mGraphQueries = new WeakHashMap<>();
mContext = context;
populateGraphQueries(ROOT_FOLDER_GRAPHQL);
}
/** Package-Private Methods **/
String getQuery(Annotation[] annotations) {
if(mGraphQueries == null || mGraphQueries.isEmpty()){
populateGraphQueries(ROOT_FOLDER_GRAPHQL);
}
GraphQuery graphQuery = null;
for (Annotation annotation : annotations) {
if (annotation instanceof GraphQuery) {
graphQuery = (GraphQuery) annotation;
break;
}
}
if (graphQuery != null) {
String fileName = String.format("%s%s", graphQuery.value(), EXT_GRAPHQL);
if (mGraphQueries != null && mGraphQueries.containsKey(fileName)) {
return mGraphQueries.get(fileName);
}
}
return null;
}
/** Private Methods **/
private void populateGraphQueries(#NonNull String path) {
try {
String[] paths = mContext.getAssets().list(path);
if (paths != null && paths.length > 0x0) {
for (String item : paths) {
String absolute = path + "/" + item;
if (!item.endsWith(EXT_GRAPHQL)) {
populateGraphQueries(absolute);
} else {
mGraphQueries.put(item, getFileContents(mContext.getAssets().open(absolute)));
}
}
}
} catch (IOException ioE) {
BaseEnvironment.onExceptionLevelLow(TAG, ioE);
}
}
private String getFileContents(InputStream inputStream) {
StringBuilder queryBuffer = new StringBuilder();
try {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
for (String line; (line = bufferedReader.readLine()) != null; )
queryBuffer.append(line);
inputStreamReader.close();
bufferedReader.close();
} catch (IOException e) {
e.printStackTrace();
}
return queryBuffer.toString();
}
}
In File "QueryContainerBuilder.java":
public class QueryContainerBuilder {
// Mask Types
private static final byte MASK_REPLACE_QUERY_ARGUMENTS = 0b1; // Invece di inviare il json con le variabili va a inserirle nella query i valori sostituendo i tipi degli argomenti.
private static final byte MASK_REPLACE_EXPLICIT_QUOTES = MASK_REPLACE_QUERY_ARGUMENTS << 0b1; // Alle stringhe non vengono automaticamente messe le virgolette ma devono essere aggiunte nei valori passati per le variabili.
private static final byte MASK_REPLACE_WITH_PLACEHOLDERS = MASK_REPLACE_EXPLICIT_QUOTES << 0b1; // Va a sostituire i placeholders "<key_var_name>" presenti nella query con i valori delle variabili.
private QueryContainer mQueryContainer;
private byte mMask;
public QueryContainerBuilder() {
mQueryContainer = new QueryContainer();
}
/** Setter Methods **/
public QueryContainerBuilder setQuery(String query) {
mQueryContainer.setQuery(query);
return this;
}
public QueryContainerBuilder setReplaceQueryArguments(){
mMask = MASK_REPLACE_QUERY_ARGUMENTS;
return this;
}
public QueryContainerBuilder setReplaceExplicitQuotes(){
mMask = MASK_REPLACE_QUERY_ARGUMENTS | MASK_REPLACE_EXPLICIT_QUOTES;
return this;
}
public QueryContainerBuilder setReplaceWithPlaceholders(){
mMask = MASK_REPLACE_QUERY_ARGUMENTS | MASK_REPLACE_WITH_PLACEHOLDERS;
return this;
}
/** Public Methods **/
public QueryContainerBuilder putVariable(String key, Object value) {
mQueryContainer.putVariable(key, value);
return this;
}
public boolean containsVariable(String key) {
return mQueryContainer.containsVariable(key);
}
/** Builder Methods **/
public QueryContainer build() {
if((mMask & MASK_REPLACE_QUERY_ARGUMENTS) != 0x0){
if((mMask & MASK_REPLACE_WITH_PLACEHOLDERS) != 0x0){
mQueryContainer.replaceVariablesPlaceholdersInQuery();
} else {
mQueryContainer.replaceVariablesInQuery(mQueryContainer.mVariables, 0x0);
}
mQueryContainer.mVariables = null;
}
return mQueryContainer;
}
/** Public Static Classes **/
public class QueryContainer {
#SerializedName("variables")
private LinkedHashMap<String, Object> mVariables;
#SerializedName("query")
private String mQuery;
QueryContainer() {
mVariables = new LinkedHashMap<>();
}
/** Private Methods **/
private void setQuery(String query) {
mQuery = query;
}
private void putVariable(String key, Object value) {
mVariables.put(key, value);
}
private boolean containsVariable(String key) {
return mVariables != null && mVariables.containsKey(key);
}
private void replaceVariablesInQuery(LinkedHashMap<String, Object> map, int index){
if(!TextUtils.isEmpty(mQuery) && map.size() > 0x0){
List<String> keys = new ArrayList<>(map.keySet());
for(String key : keys){
Object value = map.get(key);
if(value instanceof LinkedHashMap){
replaceVariablesInQuery((LinkedHashMap<String, Object>) value, index);
} else {
int i = mQuery.indexOf(key + ":", index) + key.length() + 0x1;
int z;
if(keys.indexOf(key) < keys.size() - 0x1){
z = mQuery.indexOf(",", i);
} else {
z = mQuery.indexOf(")", i);
int x = mQuery.substring(i, z).indexOf('}');
if(x != -0x1){
if(mQuery.substring(i, i + 0x4).contains("{")){
x++;
}
z -= ((z - i) - x);
}
}
String replace;
if((mMask & MASK_REPLACE_EXPLICIT_QUOTES) != 0x0){
replace = String.valueOf(value);
} else {
replace = value instanceof String ?
"\"" + value.toString() + "\"" : String.valueOf(value);
}
String sub = mQuery.substring(i, z)
.replaceAll("[\\\\]?\\[", "\\\\\\[").replaceAll("[\\\\]?\\]", "\\\\\\]")
.replaceAll("[\\\\]?\\{", "\\\\\\{").replaceAll("[\\\\]?\\}", "\\\\\\}");
mQuery = mQuery.replaceFirst(sub.contains("{}") ? sub.replace("{}", "").trim() : sub.trim(), replace);
index = z + 0x1;
}
}
}
}
private void replaceVariablesPlaceholdersInQuery(){
if(!TextUtils.isEmpty(mQuery) && mVariables.size() > 0x0){
for(String key : mVariables.keySet()){
mQuery = mQuery.replaceFirst("\\<" + key + "\\>", mVariables.get(key) != null ? mVariables.get(key).toString() : "null");
}
mVariables = null;
}
}
}
}
Put your queries in a "graphql" directory in the "assets" folder with the ".graphql" extension for your query files. You can change the extension or the folder by changing the "EXT_GRAPHQL" or "ROOT_FOLDER_GRAPHQL" constants in "GraphQueryProcessor". You can use these formats for the queries:
query {
myQuery(param1: <myParam1>) {
....
}
}
If you use this format you need to use "MASK_REPLACE_WITH_PLACEHOLDERS" in your QueryContainerBuilder. Also you need to pass as the HashMap key the name of the placeholder without the "<...>", so in this case "myParam1".
The others format are just common GraphQL queries, like:
query ($p1: String!) {
muQuery(p1: $id) {
...
}
}
With this format you can use normal QueryContainerBuilder behaviour (no mask applyed, so it will pass and generate the "variables" json object.) or the "MASK_REPLACE_QUERY_ARGUMENTS" which will remove the "$id" and place the value.
When you init Retrofit add the "GraphQLConverter". Take care about the "ConvertFactories" order! You can put more ConvertFactory, but they consume the input so if in this case you put "Gson" before "GraphQL" the "GsonConverted" will consume the input data:
new Retrofit.Builder()
.baseUrl(mBaseUrl)
.addConverterFactory(GraphQLConverter.create(context))
.addConverterFactory(GsonConverterFactory.create(gson))
.client(getBaseHttpClient(interceptor))
.build();
In your Retrofit API:
#POST(AppConstants.SERVICE_GQL)
#GraphQuery(AppConstants.MY_GRAPHQL_QUERY_FILENAME)
fun callMyGraphQlQuery(#Body query: QueryContainerBuilder): Call<MyGraphQlResponse>
Call examples:
val query = QueryContainerBuilder()
.putVariable("myParam1", myValue)
.setReplaceWithPlaceholders()
createService(API::class.java).callMyGraphQlQuery(query)
val query = QueryContainerBuilder()
.putVariable("p1", myValue)
.setReplaceQueryArguments()
createService(API::class.java).callMyGraphQlQuery(query)
val query = QueryContainerBuilder()
.putVariable("p1", myValue)
createService(API::class.java).callMyGraphQlQuery(query)
Idk if the "MASK_REPLACE_QUERY_ARGUMENTS" works right, I used it only 2/3 times and then the back-end was changed and wrote better.
I did those cases (masks) to process the queries because I had this 3 case of queries with the back-end I was calling.
You can just add others query processing behavior just by adding another mask and the code in the "QueryContainerBuilder".
If anyone use this code and change it making it better, please write me the changes so I will change the code in my library too.
Thanks you,
have a nice coding and day :D
Bye!
I got tired using this library, this is my first time using it and made a lot of success ways, but i'm a bit confused in getting the following Json :
{
"Guides":
{
"English": {"ArabicSony":"Test1","ArabicNexus":"Test2","ArabicSamsung":"Test3","ArabicHTC":"Test4"}
,"Arabic": {"EnglishSony":"Test1","EnglishNexus":"Test2","EnglishSamsung":"Test3","EnglishHTC":"Test4"}
}
}
Googled and saw a lot of guides and answered, and made my List like this :
public class PostItem {
List<PostItemArabic> Arabic;
List<PostItemEnglish> English;
}
class PostItemArabic{
private String ArabicSony;
private String ArabicNexus;
private String ArabicSamsung;
private String ArabicHTC;
public String getArabicSony() {
return ArabicSony;
}
public void setArabicSony(String arabicSony) {
ArabicSony = arabicSony;
}
public String getArabicNexus() {
return ArabicNexus;
}
public void setArabicNexus(String arabicNexus) {
ArabicNexus = arabicNexus;
}
public String getArabicSamsung() {
return ArabicSamsung;
}
public void setArabicSamsung(String arabicSamsung) {
ArabicSamsung = arabicSamsung;
}
public String getArabicHTC() {
return ArabicHTC;
}
public void setArabicHTC(String arabicHTC) {
ArabicHTC = arabicHTC;
}
}
class PostItemEnglish{
private String EnglishSony;
private String EnglishNexus;
private String EnglishSamsung;
private String EnglishHTC;
public String getEnglishSony() {
return EnglishSony;
}
public void setEnglishSony(String englishSony) {
EnglishSony = englishSony;
}
public String getEnglishNexus() {
return EnglishNexus;
}
public void setEnglishNexus(String englishNexus) {
EnglishNexus = englishNexus;
}
public String getEnglishSamsung() {
return EnglishSamsung;
}
public void setEnglishSamsung(String englishSamsung) {
EnglishSamsung = englishSamsung;
}
public String getEnglishHTC() {
return EnglishHTC;
}
public void setEnglishHTC(String englishHTC) {
EnglishHTC = englishHTC;
}
}
My Model :
private class Model {
private List<PostItem> Guides;
public List<PostItem> getGuides() {
return Guides;
}
public void setGuides(List<PostItem> roms_center) {
this.Guides = roms_center;
}
}
And printing the result like this :
List<PostItem> Guides = response.body().getGuides();
for(int i = 0 ; i < Guides.size() ; i ++ ) {
for (int b = 0; b < Guides.get(i).English.size() ; b++){
Log.LogInfo("English Result Is: " + Guides.get(i).English.get(i).getEnglishHTC());
Log.LogInfo("English Result Is: " + Guides.get(i).English.get(i).getEnglishNexus());
Log.LogInfo("English Result Is: " + Guides.get(i).English.get(i).getEnglishSamsung());
Log.LogInfo("English Result Is: " + Guides.get(i).English.get(i).getEnglishSony());
}
for (int b = 0; b < Guides.get(i).Arabic.size() ; b++){
Log.LogInfo("Arabic Result Is: " + Guides.get(i).Arabic.get(i).getArabicHTC());
Log.LogInfo("Arabic Result Is: " + Guides.get(i).Arabic.get(i).getArabicNexus());
Log.LogInfo("Arabic Result Is: " + Guides.get(i).Arabic.get(i).getArabicSamsung());
Log.LogInfo("Arabic Result Is: " + Guides.get(i).Arabic.get(i).getArabicSony());
}
}
My work isn't correct, and getting a lot of errors,
Here's the last error i got :
`Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 3 column 18 path $.Guides
What's the way to make it correct ? `
Based on your models when you try to get the guides list your telling retrofit to populate an array. Retrofit is then getting the data and finding that it is a single object and not array. So you need to update your model to reflect the data returned. For example:
class PostItem {
List<Language> mLanguages;
}
class Language{
String mLanguageTitle; //for example english
List<String> mData; //for this is your list of data
}
Then in your activity instead of getting guides you would get just a post item for example:
response.body().getPostItem();
Hope it helps !
First of all, you can use the retrofit Gson library.
You can handle this in two ways:
Option 1: reformat your languages in your json to be an array like Doug says.
{
"Guides":
[
{"Lang":"English","ArabicSony":"Test1","ArabicNexus":"Test2","ArabicSamsung":"Test3","ArabicHTC":"Test4"}
, {"Lang":"Arabic","EnglishSony":"Test1","EnglishNexus":"Test2","EnglishSamsung":"Test3","EnglishHTC":"Test4"}
]
}
Then you will need to redesign your class to reflect this structure.
Like Doug sayd:
class PostItem {
List<Language> mLanguages;
}
Option 2: Create a custom json desirializer in your class. this will take the Json and break it down into whatever structure you want it to be.
public class PostItem implements JsonDeserializer
#Override
public MyDesirializer deserialize(JsonElement json, Type type,
JsonDeserializationContext context) throws JsonParseException {
JsonObject jarabic = (JsonObject) json.get("Arabic");
//whatever manipulations you want to do (fill with your own code)
PostItem item = new PostItem();
item.arabic = jarabic;
...
...
return item;
}
We are currently working on setting up Retrofit for an XML API - unfortunately each request can return a response with one of two different root elements.
Normally, each response looks like this (of course, the actual elements contained within the <response> tag vary with each request):
<?xml version="1.0" encoding="UTF-8"?>
<response>
<SomeInfo>Some Info</SomeInfo>
<MoreInfo>More Info</MoreInfo>
</response>
And each error looks like this (the structure here is the same for each response):
<?xml version="1.0" encoding="UTF-8"?>
<error>
<code>125002</code>
<message></message>
</error>
Now, the only way we've found so far to get this work in a somewhat generic way is the following:
public interface Api {
#GET("/api/sessionToken")
Observable<ResponseBody> requestSessionToken();
#GET("/api/pinStatus")
Observable<ResponseBody> requestPinStatus();
}
public class RestClient {
public RestClient() {
// ...
mApiService = retrofit.create(Api.class);
}
public Observable<PinStatusResponse> requestPinStatus() {
return mApiService.requestPinStatus()
.flatMap(foo(PinStatusResponse.class, PinStatusResponseData.class));
}
public Observable<SessionTokenResponse> requestSessionToken() {
return mApiService.requestSessionToken()
.flatMap(foo(SessionTokenResponse.class, SessionTokenResponseData.class));
}
private final <O extends MyResponse, I> Func1<ResponseBody, Observable<T>> foo(final Class<O> outerCls, final Class<I> innerCls) {
return new Func1<ResponseBody, Observable<O>>() {
#Override
public Observable<O> call(ResponseBody responseBody) {
try {
final String xmlString = responseBody.string();
final XmlPullParser parser = Xml.newPullParser();
parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false);
parser.setInput(new ByteArrayInputStream(xmlString.getBytes(Charset.forName("UTF-8"))), null);
parser.nextTag();
final String rootTag = parser.getName();
final Serializer serializer = new Persister();
if (TextUtils.equals(rootTag, "error")) {
final MyError myError = serializer.read(MyError.class, xmlString);
return Observable.just((O) outerCls.getConstructor(MyError.class, innerCls).newInstance(myError, null));
} else if (TextUtils.equals(rootTag, "response")) {
final I data = serializer.read(innerCls, xmlString);
return Observable.just((T) outerCls.getConstructor(MyError.class, innerCls).newInstance(null, data));
}
} catch (XmlPullParserException e) {
return Observable.error(e);
} catch (IOException e) {
return Observable.error(e);
} catch (Exception e) {
return Observable.error(e);
}
return Observable.error(new Exception("Should not be reached..."));
}
};
}
}
Where the Response classes look like this:
public abstract class MyResponse<T> {
public final MyError error;
public final T data;
protected MyResponse(MyError error, T data) {
this.error = error;
this.data = data;
}
}
and:
public final class PinStatusResponse extends MyResponse<PinStatusResponseData> {
public PinStatusResponse(MyError error, PinStatusResponseData data) {
super(error, data);
}
}
And all the *Data classes correspond directly to the (non-error) XML responses.
Now, my question is: Is there really no easier way to solve this? (And if so, is this a sign of bad API design?).
This is what the #ElementUnion annotation is for. You could probably work it out using pure Retrofit+SimpleXML API by using an annotated object like so:
#Root
public class ResponseBody {
public interface IApiResponse {
}
#Root
public static class ValidResponse implements IApiResponse {
#Element(name="SomeInfo") String someInfo;
#Element(name="MoreInfo") String moreInfo;
}
#Root
public static class ErrorResponse implements IApiResponse {
#Element(name="code") int code;
#Element(name="message") String message;
}
#ElementUnion({
#Element(name="response", type=ValidResponse.class),
#Element(name="error", type=ErrorResponse.class)
})
IApiResponse apiResponse;
}
* Concrete structure of 'ValidResponse' and 'ErrorReponse' would have to be altered according to the real XML structure you have. You might also wish to consider adding 'strict=false' in their #Root.
As for your 'Api' interface, it would then have to look like this (note I've slipped in the usage of Retrofit's Call class):
public interface Api {
#GET("/api/sessionToken")
Call<ResponseBody> requestSessionToken();
#GET("/api/pinStatus")
Call<ResponseBody> requestPinStatus();
}
And finally, the call itself (to e.g. requestPinStatus()) should be worked out according to this skeletal implementation:
Call<ResponseBody> result = mApiService.requestPinStatus();
result.enqueue(new Callback<ResponseBody>() {
#Override
public void onResponse(Response<ResponseBody> response, Retrofit retrofit) {
// ...
if (response.body().apiResponse instanceof ValidResponse) {
// ...
} else if (response.body().apiResponse instanceof ErrorResponse) {
// ...
}
}
#Override
public void onFailure(Throwable t) {
// ...
}
});
For more info on ElementUnion and Simple-XML annotations, refer to this guide.
Dearest Stackoverflowers,
I was wondering if anyone knows how to solve this the best way;
I'm talking to an api which returns a json object like this:
{
"field1": "value1",
"field2": "value2",
"details": {
"nested1": 1,
"nested2": 1
}
In java I have an object (entity) which for example, would have all these fields, but with the details as loose fields, so:
field1, field2, nested1, nested2.
This because It's an android project and I can't just go saving a class with info into my entity since I'm bound to ormlite.
Is there any way to convert the fields flat into my object using GSON? note that I'm using a generic class to convert these right now straight from the API. And I want to store these fields (which contain information as an int). In the same entity.
You can write a custom type adapter to map json value to your pojo.
Define a pojo:
public class DataHolder {
public List<String> fieldList;
public List<Integer> detailList;
}
Write a custom typeAdapter:
public class CustomTypeAdapter extends TypeAdapter<DataHolder> {
public DataHolder read(JsonReader in) throws IOException {
final DataHolder dataHolder = new DataHolder();
in.beginObject();
while (in.hasNext()) {
String name = in.nextName();
if (name.startsWith("field")) {
if (dataHolder.fieldList == null) {
dataHolder.fieldList = new ArrayList<String>();
}
dataHolder.fieldList.add(in.nextString());
} else if (name.equals("details")) {
in.beginObject();
dataHolder.detailList = new ArrayList<Integer>();
} else if (name.startsWith("nested")) {
dataHolder.detailList.add(in.nextInt());
}
}
if(dataHolder.detailList != null) {
in.endObject();
}
in.endObject();
return dataHolder;
}
public void write(JsonWriter writer, DataHolder value) throws IOException {
throw new RuntimeException("CustomTypeAdapter's write method not implemented!");
}
}
Test:
String json = "{\"field1\":\"value1\",\"field2\":\"value2\",\"details\":{\"nested1\":1,\"nested2\":1}}";
GsonBuilder builder = new GsonBuilder();
builder.registerTypeAdapter(DataHolder.class, new CustomTypeAdapter());
Gson gson = builder.create();
DataHolder dataHolder = gson.fromJson(json, DataHolder.class);
Output:
About TypeAdapter:
https://google-gson.googlecode.com/svn/trunk/gson/docs/javadocs/com/google/gson/TypeAdapter.html
http://www.javacreed.com/gson-typeadapter-example/
Do custom persisters work on Android? I was trying to write one for an entity, and was having no luck in having it run when the entity gets written by the DAO. So, I tried to use the "MyDatePersister" from the examples and I am not able to get that working either.
The persister is nearly identical to the example one -> https://github.com/j256/ormlite-jdbc/blob/master/src/test/java/com/j256/ormlite/examples/datapersister/MyDatePersister.java
In my entity, I have
#DatabaseTable
public class ClickCount implements Serializable {
// other declarations
#DatabaseField(columnName = DATE_FIELD_NAME, persisterClass = MyDatePersister.class)
private Date lastClickDate;
// more code
}
Here is a link to the whole project in Bitbucket -> https://bitbucket.org/adstro/android-sandbox. It's basically one of the ORMLite Android examples with the custom persister example added.
Any feedback would be greatly appreciated.
Thanks
First off, what is the error result you're getting?
I got my custom persister to work just fine, though I didn't try to extend the DateType. Below is a JSONArrayPersister I found the need for. The confusing part is in the naming of the methods, but once they're setup properly, it should be ok.
package com.example.acme.persister;
import com.j256.ormlite.field.FieldType;
import com.j256.ormlite.field.SqlType;
import com.j256.ormlite.field.types.BaseDataType;
import com.j256.ormlite.support.DatabaseResults;
import org.json.JSONArray;
import org.json.JSONException;
import java.sql.SQLException;
public class JSONArrayPersister extends BaseDataType {
public static int DEFAULT_WIDTH = 1024;
private static final JSONArrayPersister singleTon = new JSONArrayPersister();
public static JSONArrayPersister getSingleton() {
return singleTon;
}
private JSONArrayPersister() {
super(SqlType.STRING, new Class<?>[] { String.class });
}
protected JSONArrayPersister(SqlType sqlType, Class<?>[] classes) {
super(sqlType, classes);
}
#Override
public Object parseDefaultString(FieldType fieldType, String defaultStr) {
try {
return new JSONArray(defaultStr);
} catch (JSONException ex)
{
return new JSONArray();
}
}
#Override
public Object resultToSqlArg(FieldType fieldType, DatabaseResults results, int columnPos) throws SQLException {
try {
return new JSONArray( results.getString(columnPos) );
} catch (JSONException ex)
{
return new JSONArray();
}
}
#Override
public Object resultStringToJava(FieldType fieldType, String stringValue, int columnPos) throws SQLException {
return parseDefaultString(fieldType, stringValue);
}
#Override
public int getDefaultWidth() {
return DEFAULT_WIDTH;
}
}
Then in your entity:
#DatabaseField(persisterClass = JSONArrayPersister.class)
private JSONArray something;