I have a question regarding `multipart/form-data` in Ktor 3.0 :thread:

# ktor

[Jeff Hudson]

I have a question regarding multipart/form-data in Ktor 3.0 🧵

[Jeff Hudson]

In Ktor 2.0, I had the following code (kind of)

val fileProvider = getPart()?.provider
// later in the code
fileProvider?.invoke().readRemaining().readByteArray()

fun getPart(): PartData? = {
  call.receiveMultipart().forEachPart { part ->
    if (part is PartData.FileItem) return@getPart part
  }
  return null
}

This worked fine. But in Ktor 3.0 I get an empty byte array if I do this.

Is Ktor 3.0 doing some automatic cleanup of stream or provider before I get to reading the data?

[Aleksei Tirman [JB]]

Can you please share a complete code snippet?

[Aleksei Tirman [JB]]

The problem might be due to this change.

[Jeff Hudson]

Oh yeah, the addition of

previousPart?.dispose?.invoke()

looks like it would do it. We have a try/finally that does the dispose later on.

[Jeff Hudson]

I can add a more complete code snippet later today 🙂

[Aleksei Tirman [JB]]

Feel free to file an issue if you think it's a bug.

[Jeff Hudson]

will do! thanks

[Dieppa]

Hi @Aleksei Tirman [JB], I have filed an issue related to this self-clearing of PartData. There I explain a bit why this might not be a good idea. @Jeff Hudson You might also find it interesting. https://youtrack.jetbrains.com/issue/KTOR-8125/PartData-self-clearing