Multipart Support

note

This help topic is in development and will be updated in the future.

Ktor supports handling HTTP Uploads. As well as receiving any other kind of content.

note

You can check out the Youkube example for a full example of this in action.

Receiving files using multipart

val multipart = call.receiveMultipart()
multipart.forEachPart { part ->
    when (part) {
        is PartData.FormItem -> {
            if (part.name == "title") {
                title = part.value
            }
        }
        is PartData.FileItem -> {
            val ext = File(part.originalFileName).extension
            val file = File(uploadDir, "upload-${System.currentTimeMillis()}-${session.userId.hashCode()}-${title.hashCode()}.$ext")
            part.streamProvider().use { input -> file.outputStream().buffered().use { output -> input.copyToSuspend(output) } }
            videoFile = file
        }
    }
    part.dispose()
}
suspend fun InputStream.copyToSuspend(
    out: OutputStream,
    bufferSize: Int = DEFAULT_BUFFER_SIZE,
    yieldSize: Int = 4 * 1024 * 1024,
    dispatcher: CoroutineDispatcher = Dispatchers.IO
): Long {
    return withContext(dispatcher) {
        val buffer = ByteArray(bufferSize)
        var bytesCopied = 0L
        var bytesAfterYield = 0L
        while (true) {
            val bytes = read(buffer).takeIf { it >= 0 } ?: break
            out.write(buffer, 0, bytes)
            if (bytesAfterYield >= yieldSize) {
                yield()
                bytesAfterYield %= yieldSize
            }
            bytesCopied += bytes
            bytesAfterYield += bytes
        }
        return@withContext bytesCopied
    }
}