Hi people, kinda new here... was wondering how can I accept a JSON payload in Ktor tried `call.recei...

# ktor

[John Pali]

Hi people, kinda new here... was wondering how can I accept a JSON payload in Ktor
tried call.receiveText() but it gets is to a string - had a look on the docs about serialization, but got quite confused there.

[Big Chungus]

call.receive<MyType>()

[Big Chungus]

e.g. call.receive<JsonObject>()

[Matteo Mirk]

that’s the wrong function, it just reads the request as text. First you have to install content negotiation feature:

import io.ktor.features.*
// ...
fun main() {
    embeddedServer(Netty, port = 8080) {
        install(ContentNegotiation)
        // ...
    }.start(wait = true)
}

then register a converter, for example Jackson
https://ktor.io/docs/jackson.html#register_jackson_converter. Then you execute what Martynas wrote above, yeah ⬆️

[Matteo Mirk]

to receive data you ask for a given type of your choice and Ktor will perform deserialization for you
https://ktor.io/docs/jackson.html#register_jackson_converter

[Aleksei Tirman [JB]]

Please read the docs about content negotiation and serialization

[John Pali]

I have ContentNegotiation installed.. but when I call call.receive<Entity>() I get error that some values are not provided...

[Big Chungus]

Does your json match data class? Is data class annotated as serializable?

[John Pali]

The situation is that my Entity has computed values

Entity:
id: Int,
user: User,
value: String,
computedValue: String

and Entity is a DAO for an EntityTable

The problem is that calling call.recieve<Entity>() yells that I didn't provide id, user, computedValue in the payload

[Big Chungus]

Annotate computed values with @JsonIgnore

[John Pali]

Didnt know about @JsonIgnore.

[John Pali]

Thanks!

[John Pali]

Should also the id (auto incremented) should be annotiated?

[Big Chungus]

Pretty much any serialization framework has something like that as it's a pretty standard problem 😄

[John Pali]

First time using Exposed/Ktor 🙂
Coming from a Python/NodeJS world