Retrofit2: Modifying request body in OkHttp Interceptor

Question

I am using Retrofit 2 (2.0.0-beta3) with OkHttp client in Android application and so far everything going great. But currently I am facing issue with OkHttp Interceptor. The

Answer 1

I'll share my Kotlin implementation of @Fabian's answer using Dagger. I wanted origin=app added to the request url for GET requests, and added to the body for form-encoded POST requests

@Provides
@Singleton
fun providesRequestInterceptor() =
        Interceptor {
            val request = it.request()

            it.proceed(when (request.method()) {
                "GET" -> {
                    val url = request.url()
                    request.newBuilder()
                            .url(url.newBuilder()
                                    .addQueryParameter("origin", "app")
                                    .build())
                            .build()
                }
                "POST" -> {
                    val body = request.body()
                    request.newBuilder()
                            .post(RequestBody.create(body?.contentType(),
                                    body.bodyToString() + "&origin=app"))
                            .build()
                }
                else -> request
            })
        }

fun RequestBody?.bodyToString(): String {
    if (this == null) return ""
    val buffer = okio.Buffer()
    writeTo(buffer)
    return buffer.readUtf8()
}