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Getting error "Suspension functions can be called only within coroutine body" in Kotlin

I've written one function with Flow collector which is as shown below,
private fun callSocket(
eventEmmit: String,
eventOn: String,
request: JSONObject
): Flow<SocketCallback<JSONObject>> =
flow {
try {
if (socket.connected()) {
var response = JSONObject()
Log.e("EMIT", JSONObject(Gson().toJson(request)).toString())
socket.on(
eventOn
) { args ->
response = args[0] as JSONObject
Log.e("ON", response.toString())
**this.emit(SocketCallback.OnSuccess(response))**
}.emit(
eventEmmit,
request
)
emit(SocketCallback.OnSuccess(response))
} else {
Log.e("SOCKET_ERROR", "Socket connection failed")
emit(SocketCallback.OnError("Socket connection failed"))
}
} catch (e: SocketException) {
emit(SocketCallback.OnError(e.toString()))
}
}.flowOn(Dispatchers.IO)
But when I write this.emit(SocketCallback.OnSuccess(response))(enclosed in ** in code) in on method it shows me the error "Suspension functions can be called only within coroutine body".
Any solution for this?
Thanks in advance.

You are trying to emit events to flow outside of coroutineScope. socket.on() function probably has signature:
fun on(ev: String, block: (args: String) -> Unit) {
}
in that case, inside lambda block: (args: String) -> Unit) you are outside of scope and you can not invoke suspending functions.
You have only 2 solutions:
Every time new event approach - create new coroutine with coroutine builder launch:
socket.on(
eventOn
) { args ->
response = args[0] as JSONObject
Log.e("ON", response.toString())
launch {
emit(SocketCallback.OnSuccess(response))
}
}.emit(
eventEmmit,
request
)
Use callbackFlow to avoid creation of new coroutine on each event. Please check especially this post.

Here's how I solved it by using the CallBackFlow
private fun callOnSocket(
eventOn: String
): Flow<SocketCallback<JSONObject>> =
callbackFlow<SocketCallback<JSONObject>> {
try {
if (socket.connected()) {
Log.e("ON", "Started")
var response = JSONObject()
socket.on(
eventOn
) {
response = it[0] as JSONObject
Log.e("ON", response.toString())
trySend(SocketCallback.OnSuccess(response))
}
} else {
Log.e("SOCKET_ERROR", "Socket connection failed")
trySend(SocketCallback.OnError("Socket connection failed"))
}
} catch (e: SocketException) {
trySend(SocketCallback.OnError("Socket connection failed"))
}
awaitClose { cancel() }
}.flowOn(Dispatchers.IO)

No exception/error when no internet coroutine + retrofit

I have the following setup
Service
// ItunesService
suspend fun searchItunesPodcast(#Query("term") term: String): Response<PodcastResponse>
Repository
// ItunesRepo
override suspend fun searchByTerm(term: String) = withContext(ioDispatcher) {
return#withContext itunesService.searchItunesPodcast(term)
}
ViewModel
fun searchPodcasts(term: String) {
viewModelScope.launch {
_res.value = Result.loading()
try {
val response = itunesRepo.searchByTerm(term)
if (response.isSuccessful) { // Nothing from here when no internet
_res.value = Result.success(response.body())
} else {
_res.value = Result.error(response.errorBody().toString())
}
} catch (e: Exception) {
_res.value = Result.exception(e)
}
}
}
Everything works great until i turn off mobile data/internet on my testing device. _res value stuck on Loading state. I have tried adding break point at if (response.isSuccessful) when there is no internet and it seams like val response = itunesRepo.searchByTerm(term) never returns how can I fix this

I switched to using Flow api on my Repository
override suspend fun searchPodcasts(term: String) = flow {
emit(Result.Loading)
try {
val res = itunesService.searchItunesPodcast(term)
if (res.isSuccessful)
emit(Result.Success(res.body()))
else
emit(Result.Error("Generic error: ${res.code()}"))
} catch (e: Exception) {
emit(Result.Error("Unexpected error", e))
}
}.flowOn(ioDispatcher)
Then collect the results on my ViewModels

Live Data return old response then New response always in toast in User Registration using Retrofit

PROBLEM STATEMENT
: When i press register button for register new user it show register success response in toast from live data, but when i tried to do same button trigger it show again register success response message from API & then also show phone number exist response from API in toast. It means old response return by live data too. So how can i solve this recursive live data response return issue?
HERE is the problem video link to understand issue
Check here https://drive.google.com/file/d/1-hKGQh9k0EIYJcbInwjD5dB33LXV5GEn/view?usp=sharing
NEED ARGENT HELP
My Api Interface
interface ApiServices {
/*
* USER LOGIN (GENERAL USER)
* */
#POST("authentication.php")
suspend fun loginUser(#Body requestBody: RequestBody): Response<BaseResponse>
}
My Repository Class
class AuthenticationRepository {
var apiServices: ApiServices = ApiClient.client!!.create(ApiServices::class.java)
suspend fun UserLogin(requestBody: RequestBody) = apiServices.loginUser(requestBody)
}
My View Model Class
class RegistrationViewModel : BaseViewModel() {
val respository: AuthenticationRepository = AuthenticationRepository()
private val _registerResponse = MutableLiveData<BaseResponse>()
val registerResponse: LiveData<BaseResponse> get() = _registerResponse
/*
* USER REGISTRATION [GENERAL USER]
* */
internal fun performUserLogin(requestBody: RequestBody, onSuccess: () -> Unit) {
ioScope.launch {
isLoading.postValue(true)
tryCatch({
val response = respository.UserLogin(requestBody)
if (response.isSuccessful) {
mainScope.launch {
onSuccess.invoke()
isLoading.postValue(false)
_registerResponse.postValue(response.body())
}
} else {
isLoading.postValue(false)
}
}, {
isLoading.postValue(false)
hasError.postValue(it)
})
}
}
}
My Registration Activity
class RegistrationActivity : BaseActivity<ActivityRegistrationBinding>() {
override val layoutRes: Int
get() = R.layout.activity_registration
private val viewModel: RegistrationViewModel by viewModels()
override fun onCreated(savedInstance: Bundle?) {
toolbarController()
viewModel.isLoading.observe(this, {
if (it) showLoading(true) else showLoading(false)
})
viewModel.hasError.observe(this, {
showLoading(false)
showMessage(it.message.toString())
})
binding.registerbutton.setOnClickListener {
if (binding.registerCheckbox.isChecked) {
try {
val jsonObject = JSONObject()
jsonObject.put("type", "user_signup")
jsonObject.put("user_name", binding.registerName.text.toString())
jsonObject.put("user_phone", binding.registerPhone.text.toString())
jsonObject.put("user_password", binding.registerPassword.text.toString())
val requestBody = jsonObject.toString()
.toRequestBody("application/json; charset=utf-8".toMediaTypeOrNull())
viewModel.performUserLogin(requestBody) {
viewModel.registerResponse.observe(this){
showMessage(it.message.toString())
//return old reponse here then also new reponse multiple time
}
}
} catch (e: JSONException) {
e.printStackTrace()
}
} else {
showMessage("Please Accept Our Terms & Conditions")
}
}
}
override fun toolbarController() {
binding.backactiontoolbar.menutitletoolbar.text = "Registration"
binding.backactiontoolbar.menuicontoolbar.setOnClickListener { onBackPressed() }
}
override fun processIntentData(data: Uri) {}
}

your registerResponse live data observe inside button click listener, so that's why it's observing two times! your registerResponse live data should observe data out side of button Click listener -
override fun onCreated(savedInstance: Bundle?) {
toolbarController()
viewModel.isLoading.observe(this, {
if (it) showLoading(true) else showLoading(false)
})
viewModel.registerResponse.observe(this){
showMessage(it.message.toString())
}
viewModel.hasError.observe(this, {
showLoading(false)
showMessage(it.message.toString())
})
binding.registerbutton.setOnClickListener {
if (binding.registerCheckbox.isChecked) {
try {
val jsonObject = JSONObject()
jsonObject.put("type", "user_signup")
jsonObject.put("user_name", binding.registerName.text.toString())
jsonObject.put("user_phone", binding.registerPhone.text.toString())
jsonObject.put("user_password", binding.registerPassword.text.toString())
val requestBody = jsonObject.toString()
.toRequestBody("application/json; charset=utf-8".toMediaTypeOrNull())
viewModel.performUserLogin(requestBody) {
}
} catch (e: JSONException) {
e.printStackTrace()
}
} else {
showMessage("Please Accept Our Terms & Conditions")
}
}
}

LiveData is a state holder, it's not really meant to be used as an event stream. There is a number of articles however about the topic like this one which describe the possible solutions, including SingleLiveEvent implementation taken from google samples.
But as of now kotlin coroutines library provides better solutions. In particular, channels are very useful for event streams, because they implement fan-out behaviour, so you can have multiple event consumers, but each event will be handled only once. Channel.receiveAsFlow can be very convenient to expose the stream as flow. Otherwise, SharedFlow is a good candidate for event bus implementation. Just be careful with replay and extraBufferCapacity parameters.

how to handle network exception using coroutine?

I try handling exception using coroutine. I wrote code like this, but didn't work. I can't see any log except for using try-catch. I do not want to use try catch at all function, but want to make clean code handling exception. what should I do for this?
viewmodel
private val handler = CoroutineExceptionHandler { _, exception ->
when (exception) {
is UnknownHostException -> {
showLog("login UnknownHostException : " +exception.message)
}
else -> {
}
}
}
fun login(mobile:String){
viewModelScope.launch(handler) {
try{
var login = apiRepository.login(mobile)
_isLogin.value = login
}catch(e:Exception){
}
}
}
repository
override suspend fun login(mobile: String): LoginResultData {
var result =LoginResultData()
withContext(ioDispatcher){
val request = apiServerModel.login(mobile)
val response = request.await()
result = response
}
return result
}

fun login(mobile:String){
viewModelScope.launch(handler) {
val login = apiRepository.login(mobile)
_isLogin.value = login
}
}

How To Testing (Unit and Instrumented) of Okhttp

I'm doing self-learning of android (mostly), and I'm can't grasp a concept about Testing. I tried googling and youtube but still don't get it, so I really need a sample to test my code below
Could anyone show me how to create unit test request data to server from this code?
fun fetchJSON() {
val url =baseurl + prevnext + idliga
val request = Request.Builder().url(url).build()
val client = OkHttpClient()
client.newCall(request).enqueue(object: Callback {
override fun onFailure(call: Call, e: IOException) {
}
override fun onResponse(call: Call, response: Response) {
val body = response.body()?.string()
val gson = GsonBuilder().create()
val DataMatch= gson.fromJson(body, DataPertandingan::class.java)
runOnUiThread {
rvPrevMatch.adapter= PrevAdapter(DataMatch)
}
}
})
}
And about the instrumented test, how do I test adding something to SQLite.
here is my activity code of adding data to SQLite.
private fun addToFavorite() {
try {
database.use {
insert(
Favorite.DATA_FAVORITE,
Favorite.ID_EVENT to id_event,
Favorite.DATE to tanggaltandingdet.text,
// home team
Favorite.HOME_ID to idhome,
Favorite.HOME_TEAM to timkandangdet.text,
Favorite.HOME_SCORE to skorkandangdet.text,
Favorite.HOME_GOAL_DETAILS to cetakgolkandang.text,
Favorite.HOME_LINEUP_GOALKEEPER to kiperkandang.text,
Favorite.HOME_LINEUP_DEFENSE to bekkandang.text,
Favorite.HOME_LINEUP_MIDFIELD to midkandang.text,
Favorite.HOME_LINEUP_FORWARD to strikerkandang.text,
Favorite.HOME_LINEUP_SUBSTITUTES to cadangankandang.text,
// Favorite.HOME_TEAM_BADGE to urllogokandang.text,
// away team
Favorite.AWAY_ID to idaway,
Favorite.AWAY_TEAM to timtandangdet.text,
Favorite.AWAY_SCORE to skortandangdet.text,
Favorite.AWAY_GOAL_DETAILS to cetakgoltandang.text,
Favorite.AWAY_LINEUP_GOALKEEPER to kipertandang.text,
Favorite.AWAY_LINEUP_DEFENSE to bektandang.text,
Favorite.AWAY_LINEUP_MIDFIELD to midtandang.text,
Favorite.AWAY_LINEUP_FORWARD to strikertandang.text,
Favorite.AWAY_LINEUP_SUBSTITUTES to cadangantandang.text
// Favorite.AWAY_TEAM_BADGE to urllogotandang.text
)
}
toast ("Data Telah Di Simpan" )
} catch (e: SQLiteConstraintException) {
toast("Error: ${e.message}")
}
}