How to get error body returned by server when using Retrofit + Coroutine

user_1597489 0
Viewed 1384

When using Coroutine with Retrofit in order to call network apis, in case the server returns an error (response code != 200) we will get an Exception. My question is how to find/read the error body (in Json) sent by the server through the Exception?

try{
     apiService.login()
}catch(exception:Exception){
     //How to read error body from exception
     //Error body example: {"ok":false,"error":"Incorrect username or password."}
}
retrofit kotlin-coroutines error-handling android exception
2 Answers

You will just need to do this:

(exception as? HttpException)?.response()?.errorBody()?.string()

This will return the error body in Json format.

user_15974890

For handling the error with coroutine and retrofit you have to create a Sealed class, follow the steps...

1: StateHandle Class

sealed class NetworkState {
  data class Success(val data : CharactersResponseModel) : NetworkState()
  object InvalidData : NetworkState()
  data class Error(val error : String) : NetworkState()
  data class NetworkException(val error : String) : NetworkState()
  sealed class HttpErrors : NetworkState() {
    data class ResourceForbidden(val exception: String) : HttpErrors()
    data class ResourceNotFound(val exception: String) : HttpErrors()
    data class InternalServerError(val exception: String) : HttpErrors()
    data class BadGateWay(val exception: String) : HttpErrors()
    data class ResourceRemoved(val exception: String) : HttpErrors()
    data class RemovedResourceFound(val exception: String) : HttpErrors()
  }
}

  1. Handle error or success API call

     private suspend fun fetchCharacters() : NetworkState {
 return try {
   val response = apiService.getCharacters()
   if (response.isSuccessful) {
     if (response != null) {
       NetworkState.Success(response.body()!!)
     } else {
       NetworkState.InvalidData
     }
   } else {
     when(response.code()) {
       403 -> NetworkState.HttpErrors.ResourceForbidden(response.message())
       404 -> NetworkState.HttpErrors.ResourceNotFound(response.message())
       500 -> NetworkState.HttpErrors.InternalServerError(response.message())
       502 -> NetworkState.HttpErrors.BadGateWay(response.message())
       301 -> NetworkState.HttpErrors.ResourceRemoved(response.message())
       302 -> NetworkState.HttpErrors.RemovedResourceFound(response.message())
       else -> NetworkState.Error(response.message())
     }
   }

 } catch (error : IOException) {
   NetworkState.NetworkException(error.message!!)
 }

    }

  2. Make liveData or flow to Observer the neworkState in your UI

user_90760560
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