Can you point me to some good examples and or clear document

Question

Can you point me to some good examples and or clear documentation on how to deserialize parameters when using Ktor s `ContentNegotiation` feature I ve been banging my head against the wall for ours and it is still not working for me I have parameter classes with the ` Searializable` annotation ``` Serializable data class ShowPostURL val date String val titleSlug String override val redirectTo String = null ``` and no matter what I do `call receive ` won t work I m getting `HTTP 415` errors and Ktor doesn t even log anything I ve added the serialization support as well ```install ContentNegotiation json ``` How do I fix this This is how I m trying to use it ```accept ContentType Any get operation route val input = call receive ShowPostURL class call respondText foo ```

e5l · Answer

addamsson · Answer

I ve already been there it doesn t help

addamsson · Answer

and what you linked says that it is deprecated the `serialization ` part

addamsson · Answer

and the docs don t say how to use this with `receive`

addamsson · Answer

I m supposed to see results for basically anything if I use `ContentType Any`

addamsson · Answer

this class is not received as json though

addamsson · Answer

i m trying to deserialize form the path like this

addamsson · Answer

``` foo date titleSlug redirectTo=bar```

e5l · Answer

``` install ContentNegotiation json ```

addamsson · Answer

is this even possible with `receive `

e5l · Answer

Could you try adding ` ` after json

addamsson · Answer

i tried it says it doesn t have an invoke method

addamsson · Answer

but i m not trying to deserialize form `json`

addamsson · Answer

but form path query parameters

e5l · Answer

Strange it works for me Could you share the imports you re using

addamsson · Answer

```import io ktor application call import io ktor http ContentType import io ktor request receive import io ktor response respondText import io ktor routing Routing import io ktor routing accept import io ktor routing get```

e5l · Answer

`import io ktor serialization ` could you add that one

addamsson · Answer

i added it but intellij says it is unused

addamsson · Answer

and i get 415 disappointed

e5l · Answer

I m lost Could you file an issue with snippet Let s figure out what s happening

addamsson · Answer

this is a MWE

addamsson · Answer

```import io ktor application Application import io ktor application call import io ktor application install import io ktor features ContentNegotiation import io ktor http ContentType import io ktor request receive import io ktor response respondText import io ktor routing accept import io ktor routing get import io ktor routing routing import io ktor serialization json import io ktor server engine applicationEngineEnvironment import io ktor server engine connector import io ktor server engine embeddedServer import io ktor server netty Netty import kotlinx serialization Serializable fun main args Array lt String gt val env = applicationEngineEnvironment module example connector port = 8080 host = 0 0 0 0 embeddedServer Netty env apply start wait = true Serializable data class PostURL val date String val titleSlug String val redirectTo String = null fun Application example install ContentNegotiation json routing accept ContentType Any get foo date titleSlug val input = call receive PostURL class println $input was received call respondText foo ```

addamsson · Answer

run it and call it with `<http localhost 8080 foo 2018 10 21 wtf is this html>`

addamsson · Answer

you ll get 415

addamsson · Answer

addamsson · Answer

< e5l> I put this in a `try catch` and this is what i m getting

addamsson · Answer

```io ktor features UnsupportedMediaTypeException Content type is not supported at io ktor features ContentNegotiation$Feature$install$3 invokeSuspend ContentNegotiation kt 167 at io ktor features ContentNegotiation$Feature$install$3 invoke ContentNegotiation kt at io ktor util pipeline SuspendFunctionGun loop PipelineContext kt 318 at io ktor util pipeline SuspendFunctionGun proceed PipelineContext kt 163 at io ktor util pipeline SuspendFunctionGun execute PipelineContext kt 183 at io ktor util pipeline Pipeline execute Pipeline kt 27 at io ktor request ApplicationReceiveFunctionsKt receive ApplicationReceiveFunctions kt 110 at io ktor request ApplicationReceiveFunctionsKt receive ApplicationReceiveFunctions kt 90 at org agorahq agora delivery ExampleKt$example$2$2$1 invokeSuspend Example kt 54 at org agorahq agora delivery ExampleKt$example$2$2$1 invoke Example kt at io ktor util pipeline SuspendFunctionGun loop PipelineContext kt 318 at io ktor util pipeline SuspendFunctionGun proceed PipelineContext kt 163 at io ktor util pipeline SuspendFunctionGun execute PipelineContext kt 183 at io ktor util pipeline Pipeline execute Pipeline kt 27 at io ktor routing Routing executeResult Routing kt 147 at io ktor routing Routing interceptor Routing kt 34 at io ktor routing Routing$Feature$install$1 invokeSuspend Routing kt 99 at io ktor routing Routing$Feature$install$1 invoke Routing kt at io ktor util pipeline SuspendFunctionGun loop PipelineContext kt 318 at io ktor util pipeline SuspendFunctionGun proceed PipelineContext kt 163 at io ktor features ContentNegotiation$Feature$install$1 invokeSuspend ContentNegotiation kt 107 at io ktor features ContentNegotiation$Feature$install$1 invoke ContentNegotiation kt at io ktor util pipeline SuspendFunctionGun loop PipelineContext kt 318 at io ktor util pipeline SuspendFunctionGun proceed PipelineContext kt 163 at io ktor util pipeline SuspendFunctionGun execute PipelineContext kt 183 at io ktor util pipeline Pipeline execute Pipeline kt 27 at io ktor server engine DefaultEnginePipelineKt$defaultEnginePipeline$2 invokeSuspend DefaultEnginePipeline kt 120 at io ktor server engine DefaultEnginePipelineKt$defaultEnginePipeline$2 invoke DefaultEnginePipeline kt at io ktor util pipeline SuspendFunctionGun loop PipelineContext kt 318 at io ktor util pipeline SuspendFunctionGun proceed PipelineContext kt 163 at io ktor util pipeline SuspendFunctionGun execute PipelineContext kt 183 at io ktor util pipeline Pipeline execute Pipeline kt 27 at io ktor server netty NettyApplicationCallHandler$handleRequest$1 invokeSuspend NettyApplicationCallHandler kt 40 at io ktor server netty NettyApplicationCallHandler$handleRequest$1 invoke NettyApplicationCallHandler kt at kotlinx coroutines intrinsics UndispatchedKt startCoroutineUndispatched Undispatched kt 55 at kotlinx coroutines CoroutineStart invoke CoroutineStart kt 111 at kotlinx coroutines AbstractCoroutine start AbstractCoroutine kt 158 at kotlinx coroutines BuildersKt Builders commonKt launch Builders common kt 54 at kotlinx coroutines BuildersKt launch Unknown Source at io ktor server netty NettyApplicationCallHandler handleRequest NettyApplicationCallHandler kt 30 at io ktor server netty NettyApplicationCallHandler channelRead NettyApplicationCallHandler kt 24 at io netty channel AbstractChannelHandlerContext invokeChannelRead AbstractChannelHandlerContext java 377 at io netty channel AbstractChannelHandlerContext access$600 AbstractChannelHandlerContext java 59 at io netty channel AbstractChannelHandlerContext$7 run AbstractChannelHandlerContext java 368 at io netty util concurrent AbstractEventExecutor safeExecute AbstractEventExecutor java 164 at io netty util concurrent SingleThreadEventExecutor runAllTasks SingleThreadEventExecutor java 472 at io netty channel nio NioEventLoop run NioEventLoop java 500 at io netty util concurrent SingleThreadEventExecutor$4 run SingleThreadEventExecutor java 989 at io netty util internal ThreadExecutorMap$2 run ThreadExecutorMap java 74 at io netty util concurrent FastThreadLocalRunnable run FastThreadLocalRunnable java 30 at java lang Thread run Thread java 748 ```

addamsson · Answer

it seems that i need to add support for this somehow

addamsson · Answer

but it is not in the docs how to do that

e5l · Answer

It looks like we don t support patterns in matcher

addamsson · Answer

is there no way to deserialize an url into a class open mouth

e5l · Answer

You can try using `Location` for that

addamsson · Answer

is it stable enough

e5l · Answer

addamsson · Answer

the docs say it is an experimental api

addamsson · Answer

apart from that I don t want to pollute my business logic with Ktor annotations

addamsson · Answer

that s one of the primary reasons why i m not using Spring

e5l · Answer

Yep but we re not going to break it

addamsson · Answer

is there an alternative

e5l · Answer

Yep fair point

addamsson · Answer

my business modules don t know about Ktor disappointed

e5l · Answer

Let me thing a bit

addamsson · Answer

thanks thumbsup

nschulzke · Answer

I ran into this same problem including not wanting to risk using the experimental Location API I ended up writing a short function to deserialize the parameters

addamsson · Answer

what s the difference between `call parameters` and `call receiveParameters ` It is not clear from the docs

nschulzke · Answer

`receiveParameters` gets the request body as a `Parameters` object `call parameters` is what comes in in the URL Not great naming

addamsson · Answer

oh so `receiveParameters ` is the alternative for `receive ` if you re not doing ContentNegotiation

addamsson · Answer

thx

nschulzke · Answer

In practice it seems to deserialize form data as sent by HTML forms

nschulzke · Answer

So yeah

addamsson · Answer

can i use `ContentNegotiation` with forms

addamsson · Answer

`call parameters` seems to include query parameters as well

nschulzke · Answer

Yes it does

nschulzke · Answer

A year ago I couldn t get ContentNegotiation to work with forms

addamsson · Answer

this is a bummer

addamsson · Answer

i m using forms as a fallback method if javascript doesn t work for some reason disappointed

nschulzke · Answer

I ended up using an extension function on the StringValues class to do both form deserialization and url parameters serialization

nschulzke · Answer

Since `receiveParameters` and `parameters` have the same type you can deserialize both the same way once you have a way to do one

addamsson · Answer

makes sense

addamsson · Answer

thanks

addamsson · Answer

< e5l> do you have plans for fixing this

e5l · Answer

Yep I filed an issue about the names And wrote notes about forms with `ContentNegotations` compatibility

e5l · Answer

Great thanks for the investigation

addamsson · Answer

thanks < e5l>

addamsson · Answer

i m gonna write a `receiveAs ` method for the time being on the `Parameters` class

addamsson · Answer

so is there something I can do if I want to enable receiving data structures as json and as form data as well

addamsson · Answer

what i m trying ot do is to have regular forms

addamsson · Answer

which are enhanced if javascript is present

addamsson · Answer

to API calls

nschulzke · Answer

Yeah I was doing something similar I check the content type If it s application json I deserialize with the normal `receive` method if it s not I deserialize with `receiveParameters` and my extension

addamsson · Answer

but right now i can t use the same receiving logic for both

nschulzke · Answer

All that is behind an extension function on `PipelineContext lt Unit ApplicationCall gt ` so you don t have to have the checks everywhere

addamsson · Answer

what do you mean

addamsson · Answer

can you post an example

nschulzke · Answer

Not the actual code but close ```PipelineContext lt Unit ApplicationCall gt myReceive type KClass lt T gt if request contentType match ContentType Application Json receive type else receiveParameters myDeserialize type ``` So if it s JSON the extension acts as though it s just the `receive` method Otherwise it uses the custom deserialization

nschulzke · Answer

It doesn t save any overhead on the checks but it means you don t have to think about them when actually writing route code

nschulzke · Answer

<https ktor io servers features content negotiation html> It looks like you could also write your own ContentConverter that handles it for you and register it I m not sure why I didn t find this last year maybe the docs on this are new but this actually looks like a better way if it works

nschulzke · Answer

So form data may not be natively supported but once you have a way to deserialize you could use the native `receive` method and just register a new `ContentConverter`

addamsson · Answer

thanks this is great