Output based on input?

rleibman · January 8, 2024, 6:16pm

Hi!
So, depending on a field of my input object (json), I want to either respond with a method that will return a ZIO[R,E,Something] or ZStream[R, E, Something]. I’m not sure how to code that?.
It seems like what I want is somewhat like oneOf, but I’m not sure how to do this properly:

val myEndpoint = endpoint.post
    .name("report")
    .description("Runs a report, returning a json stream if requested")
    .in("a" / "report")
    .in(jsonBody[MyRequest])
    .out(
      oneOf(
        oneOfVariant(jsonBody[MyResponse]), //Do this if request.doStream = false 
        oneOfVariant(streamBody(ZioStreams)(Schema.schemaForString, CodecFormat.TextPlain()).toEndpointIO) // Do this if request.doStream = true
      )
    )

and obviously my impl would be something like:

    val myEndopintImpl = myEndpoint.zServerLogic[Any] { (req: MyRequest) =>
      if(req.doStream)
        reports.streamIt() //returns ZStream[A, Nothing, String]
      else
        reports.doIt() // which returns ZIO[A, B, MyResponse]
    }

adamw · January 9, 2024, 11:32am

You can try oneOf bodies, see here. That’s not an entirely dynamic solution, as you’ll need different data types for both branches, but I think might do the trick.

rleibman · January 9, 2024, 4:42pm

I tried oneOfBody but I got an error about erasure, I don’t know how to get past that, in the examples it’s all about the status error, which is different from my case.
Thanks for the help.

adamw · January 9, 2024, 6:08pm

Hm maybe you can share some code or a simplified example, which would show the problem? Then we might be able to help

rleibman · January 9, 2024, 6:51pm

I did
So… given the following implementation:

val myEndopintImpl = myEndpoint.zServerLogic[Any] { (req: MyRequest) =>
      if(req.doStream)
        reports.streamIt() //returns ZStream[A, Nothing, String]
      else
        reports.doIt() // which returns ZIO[A, B, MyResponse]
    }

What would be the declaration of myEndpoint?

adamw · January 10, 2024, 10:18am

So the error message suggests what might be the fix - you can’t use generic types in oneOfVariant, as run-time checks which variant to use are unreliable then.

One option is to use oneOfDefaultVariant:

val myEndpoint = endpoint.get
    .in(query[Boolean]("stream"))
    .out(
      oneOf(
        oneOfVariant(jsonBody[MyResponse]),
        oneOfDefaultVariant(streamBody(ZioStreams)(Schema.schemaForString, CodecFormat.TextPlain()).toEndpointIO)
      )
    )

Or a class matcher:

val myEndpoint = endpoint.get
    .in(query[Boolean]("stream"))
    .out(
      oneOf(
        oneOfVariant(jsonBody[MyResponse]),
        oneOfVariantClassMatcher(
          streamBody(ZioStreams)(Schema.schemaForString, CodecFormat.TextPlain()).toEndpointIO,
          classOf[ZStream[_, _, _]]
        )
      )
    )

However, I can’t test this using zio-http, as I’m getting an exception when trying the streaming branch:

timestamp=2024-01-10T10:17:25.469592Z level=WARN thread=#zio-fiber-39 message="Fatal exception in Netty" cause="Exception in thread "zio-fiber-" io.netty.handler.codec.EncoderException: java.lang.IllegalStateException: unexpected message type: DefaultFullHttpResponse, state: 2
	at io.netty.handler.codec.http.HttpObjectEncoder.write(HttpObjectEncoder.java:108)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:881)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:863)
	at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:968)
	at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:856)
	at io.netty.channel.ChannelDuplexHandler.write(ChannelDuplexHandler.java:115)
	at io.netty.handler.codec.http.HttpServerKeepAliveHandler.write(HttpServerKeepAliveHandler.java:87)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:879)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:863)
	at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:968)
	at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:856)
	at io.netty.channel.ChannelDuplexHandler.write(ChannelDuplexHandler.java:115)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:879)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:940)
	at io.netty.channel.AbstractChannelHandlerContext$WriteTask.run(AbstractChannelHandlerContext.java:1247)
	at io.netty.util.concurrent.AbstractEventExecutor.runTask(AbstractEventExecutor.java:173)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:166)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:470)
	at io.netty.channel.kqueue.KQueueEventLoop.run(KQueueEventLoop.java:300)
	at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997)
	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.base/java.lang.Thread.run(Thread.java:833)
	Suppressed: java.lang.IllegalStateException: unexpected message type: DefaultFullHttpResponse, state: 2
		at io.netty.handler.codec.http.HttpObjectEncoder.throwUnexpectedMessageTypeEx(HttpObjectEncoder.java:348)
		at io.netty.handler.codec.http.HttpObjectEncoder.encodeFullHttpMessage(HttpObjectEncoder.java:305)
		at io.netty.handler.codec.http.HttpObjectEncoder.encode(HttpObjectEncoder.java:162)
		at io.netty.handler.codec.http.HttpObjectEncoder.write(HttpObjectEncoder.java:97)
		at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:881)
		at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:863)
		at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:968)
		at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:856)
		at io.netty.channel.ChannelDuplexHandler.write(ChannelDuplexHandler.java:115)
		at io.netty.handler.codec.http.HttpServerKeepAliveHandler.write(HttpServerKeepAliveHandler.java:87)
		at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:879)
		at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:863)
		at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:968)
		at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:856)
		at io.netty.channel.ChannelDuplexHandler.write(ChannelDuplexHandler.java:115)
		at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:879)
		at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:940)
		at io.netty.channel.AbstractChannelHandlerContext$WriteTask.run(AbstractChannelHandlerContext.java:1247)
		at io.netty.util.concurrent.AbstractEventExecutor.runTask(AbstractEventExecutor.java:173)
		at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:166)
		at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:470)
		at io.netty.channel.kqueue.KQueueEventLoop.run(KQueueEventLoop.java:300)
		at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997)
		at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
		at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
		at java.base/java.lang.Thread.run(Thread.java:833)"

Does it work for you?

adamw · January 10, 2024, 10:56am

It seems this occurs when I’m using too short bodies, see "unexpected message type: DefaultFullHttpResponse" with certain response streams · Issue #2608 · zio/zio-http · GitHub

With longer/async bodies things work fine

rleibman · January 10, 2024, 2:58pm

Awesome, thanks, I’ll give that a try, it’ll be a bit before all my refactoring to use tapir is done for me to try running it.

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Output based on input?

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