hey is there an easy way to change how the top-lev...

# apollo-kotlin

[agrosner]

hey is there an easy way to change how the top-level response is handled . Context: I want to rewrite the response:
a server graphql endpoint (non-federated) returns data like:

{
	"summary": {
		....
	},
	"response": {
		"data": {

vs the expected:

{
	"errors": ...,
	"data": {

[agrosner]

use-case - i want the apollo client, with code generation etc, but the response shape is a little different.

I tried using an Httpinterceptor but it never reaches that interceptor, and didnt know how to convert the stream to a subset of json

[mbonnin]

That's highly unusual for a GraphQL server so I'd recommend fixing that in the backend if possible (you can put "summary" in an "extensions" field IIRC)

[mbonnin]

But if you have no control over hte backend, I was going to suggest HttpInterceptor indeed

[mbonnin]

Let me check quickly

[agrosner]

yeah its unusual haha. its a legacy graphql api, that we cannot move off of right away. (lots of uses in our company for it, but the move to federation is in progress).

[agrosner]

sure, thank you! all i want to be able to do is skip to the response . which will follow similiar format as regular graphql responses

[mbonnin]

val mockServer = MockServer()
    val apolloClient = ApolloClient.Builder()
        .serverUrl(mockServer.url())
        .addHttpInterceptor(object: HttpInterceptor {
          override suspend fun intercept(request: HttpRequest, chain: HttpInterceptorChain): HttpResponse {
            val response = chain.proceed(request)

            val json = AnyAdapter.fromJson(response.body!!.jsonReader(), CustomScalarAdapters.Empty) as Map<String, Any?>

            val jsonString = buildJsonString {
              writeAny(json["response"])
            }

            return HttpResponse.Builder(response.statusCode)
                .body(jsonString.encodeUtf8())
                .headers(response.headers)
                .build()
          }
        })
        .build()

    mockServer.enqueue("""
      {
        "summary": "something something",
        "response": {
          "data": {
            "hero": {
              "__typename": "Droid",
              "name": "R2-D2"
            }
          }
        }
      }
    """.trimIndent())

    val data = apolloClient.query(EpisodeHeroNameQuery(Episode.NEWHOPE)).execute().data

[mbonnin]

That's a very crude working example

[mbonnin]

A better implementation would stream the Json

[mbonnin]

(instead of converting everything to a Map in both direction like here)

[agrosner]

ah interesting. i had this to test:

.addHttpInterceptor(object: HttpInterceptor {
    override suspend fun intercept(request: HttpRequest, chain: HttpInterceptorChain): HttpResponse {
        val response = chain.proceed(request)
        val body = response.body!!
        return response.newBuilder()
            .body(body)
            .build()
    }
})

obviously doesnt actually do anything but it wasnt even hitting this breakpoint. im going to try again

[mbonnin]

response.newBuilder().body(body)

this fails on "impossible to set body twice"

[mbonnin]

This is a bit weird. We could close the previously existing source silently but that's a bit awkward

[mbonnin]

We should certainly take a look at what OkHttp is doing, pretty sure they have solved this issue

[mbonnin]

BTW, if you're Android-only, you can use OkHttp interceptors for this

[agrosner]

thanks! yeah I searched for okhttp samples, but nothing looked good.

[agrosner]

ill try your sample first, and try to get it working with streaming

[agrosner]

that worked! thank you.

[mbonnin]

Sure thing!

[agrosner]

@Suppress("BlockingMethodInNonBlockingContext")
    override suspend fun intercept(request: HttpRequest, chain: HttpInterceptorChain): HttpResponse {
        val response = chain.proceed(request)

        val bodySource = extractNestedResponse(response)
        return HttpResponse.Builder(response.statusCode)
            .body(bodySource)
            .headers(response.headers)
            .build()
    }

    private fun extractNestedResponse(response: HttpResponse) =
        Buffer().apply {
            @Suppress("UNCHECKED_CAST")
            val json = AnyAdapter.fromJson(response.body!!.jsonReader(), CustomScalarAdapters.Empty) as Map<String, Any?>
            BufferedSinkJsonWriter(this, null).writeAny(json["response"])
        }

bit more efficient, as we just use a buffer directly rather than turn it into string and encode utf8 back again.