Code for the article: "Uploading a file with progress in Kotlin"

AttachmentUploader.kt

fun uploadAttachment(
    filename: String, file: File, mimeType: String
): Observable<AttachmentUploadRemoteResult> {
    val progressEmitter = PublishSubject.create<Double>()
    val uploadRequest = createUploadRequest(
        filename, file, mimeType, progressEmitter
    )

    val uploadResult = uploadRequest
        .map<AttachmentUploadRemoteResult> { 
            CountingRequestResult.Completed(it.result) 
        }
        .toObservable()

    val progressResult = progressEmitter
        .map<AttachmentUploadRemoteResult> { 
            CountingRequestResult.Progress(it) 
        }

    return progressResult.mergeWith(uploadResult)
}

typealias AttachmentUploadRemoteResult = 
    CountingRequestResult<AttachmentUploadedRemoteDto>