Develop Reference

Spotify API returns string as callback result instead of json

I am using Spotify API to login user to the app. this is the interface i wrote per documentation:
interface API {
#GET("/authorize")
fun login(#Query("client_id") client_id:String,
#Query("response_type") response_type:String,
#Query("redirect_uri")redirect_uri:String,
#Query("scope") scope:String
):Call<LoginResult>
This is the response result data class:
data class LoginResult(
val code: String
)
And this is the login function:
fun login() {
val BASE_URL = "https://accounts.spotify.com"
val CLIENT_ID = "c6c23e3e2f604f9aa1780fe7504e73c6"
val REDIRECT_URI = "com.example.myapp://callback"
val retrofit: Retrofit = Retrofit.Builder().baseUrl(BASE_URL)
.addConverterFactory(GsonConverterFactory.create()).build()
val service: API = retrofit.create(API::class.java)
val listCall: Call<LoginResult> =
service.login(CLIENT_ID, "code", REDIRECT_URI, "user-top-read")
listCall.enqueue(object : Callback<LoginResult> {
override fun onResponse(response: Response<LoginResult>?, retrofit: Retrofit?) {
if (response?.body() != null) {
Log.i("result!", response.body().code)
}
if(response?.body() == null){
Log.i("Code" , response!!.code().toString())
Log.i("Response! ", "null response body")
}
}
override fun onFailure(t: Throwable?) {
Log.e("Here", "it is")
Log.e("Error", t!!.message.toString())
}
})
}
But I am getting this error:
E/Here: it is
E/Error: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 2 column 1 path $
There are a lot of questions here about this particular error and I read all of them and tried to implement the suggested solutions, but none worked.
Any help would be appreciated.
[this is the mentioned documentation link]
(https://developer.spotify.com/documentation/general/guides/authorization/code-flow/)

403 Forbidden. The request signature we calculated does not match signature you provided. Check your key and signing method from Android to Amazon S3

I am trying to call get api using an AWS signing method but not able to get the response.
Below is my code.
val secretkey = "E+t5/nDf6/NKNJBjbsdjv"
val accesskey = "DJKSBDKSBNKFGNBFG"
val credentials: AWSCredentials = BasicAWSCredentials(accesskey, secretkey)
val API_GATEWAY_SERVICE_NAME = "s3"
val requestAws: Request<*> = DefaultRequest<Any?>(API_GATEWAY_SERVICE_NAME)
val uri = URI.create("https://s3.us-west-2.amazonaws.com/..../../sample")
requestAws.endpoint = uri
requestAws.resourcePath = "https://s3.us-west-2.amazonaws.com/..../../sample"
requestAws.httpMethod = HttpMethodName.GET
val signer = AWS4Signer() signer . setServiceName (API_GATEWAY_SERVICE_NAME)
signer.setRegionName("us-west-2")
signer.sign(requestAws, credentials)
val headers = requestAws.headers
val key: MutableList<String> = ArrayList()
val value: MutableList<String> = ArrayList()
for ((key1, value1) in headers)
{
key.add(key1) value . add (value1)
}
val httpClient = OkHttpClient()
val request: okhttp3.Request = okhttp3.Request.Builder()
.url("https://s3.us-west-2.amazonaws.com/..../../sample")
.addHeader(key[0], value[0])
.addHeader(key[1], value[1])
.addHeader(key[2], value[2])
.addHeader("X-Amz-Content-Sha256",
"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855")
.build()
val response: okhttp3.Response = httpClient.newCall(request).execute()
Log.i("LOG", response.body.toString())
Not able to figure out, what I am doing mistake.
Please help me out with this issue.

If you want to create an Android app written in Kotlin and invokes AWS Services, use the AWS SDK for Kotlin.
This SDK has strongly typed Service Clients that you can use in an Android Studio project that lets you invoke a given service. (as opposed to using okhttp3.Request, etc)
For example, here is Kotlin code that invoke SNS using a Strongly typed service client named SnsClient.
// Get all subscriptions.
fun getSubs(view: View) = runBlocking {
val subList = mutableListOf<String>()
val snsClient: SnsClient = getClient()
try {
val request = ListSubscriptionsByTopicRequest {
topicArn = topicArnVal
}
val response = snsClient.listSubscriptionsByTopic(request)
response.subscriptions?.forEach { sub ->
subList.add(sub.endpoint.toString())
}
val listString = java.lang.String.join(", ", subList)
showToast(listString)
} catch (e: SnsException) {
println(e.message)
snsClient.close()
}
}
fun getClient() : SnsClient{
val staticCredentials = StaticCredentialsProvider {
accessKeyId = "<Enter key>"
secretAccessKey = "<Enter key>"
}
val snsClient = SnsClient{
region = "us-west-2"
credentialsProvider = staticCredentials
}
return snsClient
}
TO learn how to use the AWS SDK for Kotlin, see
AWS SDK for Kotlin Developer Guide

How to use refershToken in ktor

Hey I am working in kotlin multiplatform moblie. I want to ask that if api returns 401 status, I want to call refresh api. I am reading the doc to configure ktor but unable to understand this. Can someone guide me on this. I tried some code in my side, Can some one guide me any proper example how to achieve in my solution.
commonMain
expect fun httpClient(config: HttpClientConfig<*>.() -> Unit = {}): HttpClient
iOSMain
actual class Platform actual constructor() {
actual val versionCode =
platform.Foundation.NSBundle.mainBundle.infoDictionary?.get("CFBundleVersion").toString()
actual val accessToken = ""
}
androidMain
actual fun httpClient(config: HttpClientConfig<*>.() -> Unit) = HttpClient(OkHttp) {
config(this)
install(ContentNegotiation) {
json(Json {
prettyPrint = true
ignoreUnknownKeys = true
explicitNulls = false
})
}
engine {
config {
retryOnConnectionFailure(true)
connectTimeout(30, TimeUnit.SECONDS)
readTimeout(40, TimeUnit.SECONDS)
}
}
defaultRequest {
header("Client-Version", Platform().versionCode)
}
HttpResponseValidator {
validateResponse { response ->
when (response.status.value) {
401 -> {
}
}
}
}
install(Auth) {
bearer {
loadTokens {
BearerTokens(tokenProvider.accessToken, "")
}
}
}
}
Platform.kt
package com.example.kotlinmultiplatformsharedmodule
lateinit var provider: VersionAndroidProvider
lateinit var tokenProvider: AndroidToken
actual class Platform actual constructor() {
actual val versionCode get() = provider.version
actual val accessToken: String
get() = tokenProvider.accessToken
}
interface VersionAndroidProvider {
val version: String
}
interface AndroidToken {
val accessToken: String
}
I need to call api, if api returns 401 status, I need to call refershToken api. After getting new accessToken from refreshToken api, I need to send this to api call.
If refreshToken is giving 401 then I need to infrom my application to logout.

If you use the Bearer provider in Ktor’s Authentication plugin then the refreshTokens lambda will be called when a server returns 401. For more information read the documentation. Here is an incomplete example for your use case:
val client = HttpClient(Apache) {
install(Auth) {
bearer {
loadTokens {
BearerTokens("initial_access_token", "initial_refresh_token")
}
refreshTokens {
val response = client.get("https://example.com/get_token")
if (response.status == HttpStatusCode.Unauthorized) {
// logout
null
} else {
// get token from a response
BearerTokens("new_access_token", "new_refresh_token")
}
}
}
}
}

How to setup AWS SNS Push Notification in Android

Trying to create Endpoints using ARN and device token.
For generating the endpoints I have used the below class in Android Application.
I am not receiving notification from AWS SNS, is there anything that I'm missing to add in the code?
To generate device token I have added this line.
var token = FirebaseInstanceId.getInstance().token
class EndpointRegistration {
companion object {
var client = AmazonSNSClient() //provide credentials here
val awsCredentials: AWSCredentials = BasicAWSCredentials(BuildConfig.AWS_ACCESS, BuildConfig.AWS_SECRET_KEY)
var arnStorage: String? = null
fun registerWithSNS(userToken: String, context: Context) {
var endpointArn: String? = retrieveEndpointArn()
val token = userToken
var updateNeeded = false
var createNeeded = null == endpointArn
if (createNeeded) {
// No platform endpoint ARN is stored; need to call createEndpoint.
endpointArn = createEndpoint(context, token)
createNeeded = false
}
println("Retrieving platform endpoint data...")
// Look up the platform endpoint and make sure the data in it is current, even if
// it was just created.
try {
val geaReq = GetEndpointAttributesRequest()
.withEndpointArn(endpointArn)
val geaRes: GetEndpointAttributesResult = client.getEndpointAttributes(geaReq)
updateNeeded = (geaRes.attributes["Token"] != token
|| !geaRes.attributes["Enabled"].equals("true", ignoreCase = true))
} catch (nfe: NotFoundException) {
// We had a stored ARN, but the platform endpoint associated with it
// disappeared. Recreate it.
createNeeded = true
}
if (createNeeded) {
createEndpoint(context, token)
}
println("updateNeeded = $updateNeeded")
if (updateNeeded) {
// The platform endpoint is out of sync with the current data;
// update the token and enable it.
println("Updating platform endpoint $endpointArn")
val attribs: MutableMap<String, String> = HashMap()
attribs["Token"] = token
attribs["Enabled"] = "true"
val saeReq = SetEndpointAttributesRequest()
.withEndpointArn(endpointArn)
.withAttributes(attribs)
client.setEndpointAttributes(saeReq)
Log.d("Updatingd", "=" + client.endpointPrefix)
}
}
private fun createEndpoint(context: Context, token: String): String? {
var endpointArn: String? = null
endpointArn = try {
println("Creating platform endpoint with token $token")
client = AmazonSNSClient(awsCredentials)
client.setRegion(Region.getRegion(Regions.EU_WEST_1));
val cpeReq = CreatePlatformEndpointRequest()
.withPlatformApplicationArn(BuildConfig.PLATFORM_ARN)
.withToken(token)
val cpeRes: CreatePlatformEndpointResult = client
.createPlatformEndpoint(cpeReq)
cpeRes.endpointArn
} catch (ipe: InvalidParameterException) {
val message: String = ipe.getErrorMessage()
println("Exception message: $message")
val p: Pattern = Pattern
.compile(".*Endpoint (arn:aws:sns[^ ]+) already exists " +
"with the same [Tt]oken.*")
val m: Matcher = p.matcher(message)
if (m.matches()) {
// The platform endpoint already exists for this token, but with
// additional custom data that
// createEndpoint doesn't want to overwrite. Just use the
// existing platform endpoint.
m.group(1)
} else {
// Rethrow the exception, the input is actually bad.
throw ipe
}
}
storeEndpointArn(endpointArn!!)
return endpointArn
}
/**
* #return the ARN the app was registered under previously, or null if no
* platform endpoint ARN is stored.
*/
private fun retrieveEndpointArn(): String? {
// Retrieve the platform endpoint ARN from permanent storage,
// or return null if null is stored.
return arnStorage
}
/**
* Stores the platform endpoint ARN in permanent storage for lookup next time.
*/
private fun storeEndpointArn(endpointArn: String) {
// Write the platform endpoint ARN to permanent storage.
arnStorage = endpointArn
}
}
}

Using Coroutine runblock with the Authenticator to handle 401 response from retrofit

I am trying to use the Authenticator to handle 401 response. What I have done is
fun provideAccessTokenAuthenticator(
mainApiServiceHolder: MainApiServiceHolder,
preferences: SharedPreferences
) = object : Authenticator {
override fun authenticate(route: Route?, response: Response): Request? {
val accessToken = preferences.getString(ACCESS_TOKEN, null)
if (!isRequestWithAccessToken(response) || accessToken == null) {
return null
}
synchronized(this) {
val newAccessToken = preferences.getString(ACCESS_TOKEN, null)!!
// Access token is refreshed in another thread.
if (accessToken != newAccessToken) {
return newRequestWithAccessToken(response.request, newAccessToken)
}
// Need to refresh an access token
val refreshTokenResponse = runBlocking {
Log.d("zzzzzzzzzz", "refresh token is running")
mainApiServiceHolder.mainApiService?.refreshToken(
"refresh_token",
preferences.getString(REFRESH_TOKEN, null)!!,
AuthRepository.CLIENT_ID,
AuthRepository.CLIENT_SECRET
)
}
Log.d("zzzzzzzzzz", refreshTokenResponse?.body()?.access_token!!)
return if (refreshTokenResponse?.isSuccessful!!) {
Log.d("zzzzzzzzzz", "refresh token is successful")
newRequestWithAccessToken(
response.request,
refreshTokenResponse.body()?.access_token!!
)
} else {
Log.d("zzzzzzzzzz", "refresh token is unsuccessful")
response.request.newBuilder().header("Content-Type", "application/json").build()
}
}
}
Now, it gets called when there is a 401 response. The refresh token call is also fired (from Log). However, it never gets the result in the refreshTokenResponse and nothing happens after that. I think its a wrong way of using runBlock. The api is
#FormUrlEncoded
#POST("/api/auth/token/")
suspend fun refreshToken(
#Field("grant_type") grant_type: String,
#Field("refresh_token") refresh_token: String,
#Field("client_id") client_id: String,
#Field("client_secret") client_secret: String
): Response<LoginResponse>
Any help would be really appreciated. Thanks

In the Retrofit API, consider replacing your async runBlocking{} suspend fun with a synchronous Call. I had the most luck avoiding the use of coroutines inside the Authenticator.
I was having the same problem. The token request went straight into a black hole. The app froze. The request was never seen again. No error, no nothing.
But everywhere else in the app, the suspend fun came back just fine. From ViewModels, from WorkManager, it worked every time. But from the Authenticator, never. What was wrong with the Authenticator? What was special about the Authenticator that made it act this way?
Then I replaced the runBlocking{} coroutine with a straightforward Call. This time, the request came back and the token arrived without a fuss.
The way I got the API to work looked like this:
#FormUrlEncoded
#POST("token")
fun refreshTokenSync(
#Field("refresh_token") refreshToken: String,
): Call<RefreshMyTokenResponse>
Then, in the Authenticator:
val call = API.refreshTokenSync(refreshToken)
val response = call.execute().body()
I hope this helps someone else who ran into the same issue. You may receive a warning from Android Studio that this is an inappropriate blocking call. Ignore it.

Refresh token only once for multiple requests
Log out user if refreshToken failed
Log out if user gets an error after first refreshing
Queue all requests while token is being refreshed
https://github.com/hoc081098/Refresh-Token-Sample/blob/master/app/src/main/java/com/hoc081098/refreshtokensample/data/remote/interceptor/AuthInterceptor.kt
class AuthInterceptor #Inject constructor(
private val userLocalSource: UserLocalSource,
private val apiService: Provider<ApiService>,
) : Interceptor {
private val mutex = Mutex()
override fun intercept(chain: Interceptor.Chain): Response {
val req = chain.request().also { Timber.d("[1] $it") }
if (NO_AUTH in req.headers.values(CUSTOM_HEADER)) {
return chain.proceedWithToken(req, null)
}
val token =
runBlocking { userLocalSource.user().first() }?.token.also { Timber.d("[2] $req $it") }
val res = chain.proceedWithToken(req, token)
if (res.code != HTTP_UNAUTHORIZED || token == null) {
return res
}
Timber.d("[3] $req")
val newToken: String? = runBlocking {
mutex.withLock {
val user =
userLocalSource.user().first().also { Timber.d("[4] $req $it") }
val maybeUpdatedToken = user?.token
when {
user == null || maybeUpdatedToken == null -> null.also { Timber.d("[5-1] $req") } // already logged out!
maybeUpdatedToken != token -> maybeUpdatedToken.also { Timber.d("[5-2] $req") } // refreshed by another request
else -> {
Timber.d("[5-3] $req")
val refreshTokenRes =
apiService.get().refreshToken(RefreshTokenBody(user.refreshToken, user.username))
.also {
Timber.d("[6] $req $it")
}
val code = refreshTokenRes.code()
if (code == HTTP_OK) {
refreshTokenRes.body()?.token?.also {
Timber.d("[7-1] $req")
userLocalSource.save(
user.toBuilder()
.setToken(it)
.build()
)
}
} else if (code == HTTP_UNAUTHORIZED) {
Timber.d("[7-2] $req")
userLocalSource.save(null)
null
} else {
Timber.d("[7-3] $req")
null
}
}
}
}
}
return if (newToken !== null) chain.proceedWithToken(req, newToken) else res
}
private fun Interceptor.Chain.proceedWithToken(req: Request, token: String?): Response =
req.newBuilder()
.apply {
if (token !== null) {
addHeader("Authorization", "Bearer $token")
}
}
.removeHeader(CUSTOM_HEADER)
.build()
.let(::proceed)
}