Currently the following exists.

val apolloOkHttpBuilder = OkHttpClient.Builder()
   .connectTimeout(connectTimeout,TimeUnit.SECONDS)
   .writeTimeout(writeTimeout,TimeUnit.SECONDS)
   .readTimeout(readTimeout,TimeUnit.SECONDS)
   .addInterceptor(ErrorInterceptor(context))
   .addInterceptor(AuthorizationInterceptor())
   .addInterceptor(MetadataInterceptor())

…

val apolloClient = ApolloClient.Builder()
   .serverUrl(url)
   .normalizedCache(
       cacheFactory,
       cacheKeyGenerator = cacheKeyGenerator,
       cacheResolver = cacheKeyResolver,
   )
   .storePartialResponses(true)
   .fetchPolicy(FetchPolicy.CacheFirst)
   .okHttpClient(
       apolloOkHttpBuilder.build()
   )
   .interceptors(listOf(ApolloErrorInterceptor()))
   .build()

ErrorInterceptor is based off of https://stackoverflow.com/a/65469952/13215280 If an error exists, it returns an http status code 999 and adds a header with the content of it. It retrieves the msg in the ApolloErrorInterceptor

class ApolloErrorInterceptor: ApolloInterceptor {
   override fun <D : Operation.Data> intercept(
       request: ApolloRequest<D>,
       chain: ApolloInterceptorChain
   ): Flow<ApolloResponse<D>> {
       val response = chain.proceed(request)
       return response.catch { e ->
           when(e) {
               is ApolloHttpException -> {
                   val header = e.headers.find { it.name == EXCEPTION_HEADER_NAME }
                   header?.let { throw ApolloNetworkException(it.value) }
               }
           }
       }
   }
}

This currently allows us to get the error but for some reason the cache is now breaking and optimisticUpdates are failing to be applied. Specifically

java.lang.IllegalStateException: no cache configured

I found a similar thread but I don’t understand it completely. https://github.com/apollographql/apollo-kotlin/issues/2968 Is it possible to accomplish this? Any resources/docs/links? Many Thanks!

Oh! also currently using

apollo_version = '3.0.0'

which is awesome! I was able to perform a refactor and remove a ton of code.

.interceptors(listOf(ApolloErrorInterceptor()))

Looks like this is the issue. This is going to reset the ApolloCacheInterceptor that is internally set by

normalizedCache

Maybe we should hide

interceptors()

actually. This is a dangerous API 🤔

In all cases, use

addInterceptor()

instead of

interceptors()

and you should be good