How to send JSON String with POST using ktor kotlin? - json

Question

How to add JSON String in the POST request using kotlin and ktor?
Printing it out the Json string read from file or even constructed string with Kotlin in the client, the content looks like JSON.
Still, the server cannot recognize the string as JSON, and when I print it in the server, each double quota is back slashed.
The client obviously adds the back slashes, thus the request is not formatted as it should.
Client Kotlin - Ktor code:
import com.google.gson.*
import io.ktor.client.*
import io.ktor.http.*
...
val client = HttpClient(OkHttp) {
install(JsonFeature) {
serializer = GsonSerializer()
}
}
val fileContent = MyClass::class.java.getResource("myfile").readText()
println("fileContent string = $fileContent")
val out = client.post<String> {
url(url)
contentType(ContentType.Application.Json)
body = fileContent
}
the print out looks like this :
{ "name": "myname", "value": "myvalue" }
but the server (I use hookbin by the way to really print out the data without Jackson conversions) prints out:
{ \"name\": \"myname\", \"value\": \"myvalue\" }

Answer 1

The solution is to pass to the HTTP POST request a JSON object not a String object. They look the same when you print them, but of course they are not equally interpreted by the JVM. So, we have just to parse the string. I use the GSON library.
Add the JsonParser -> parseString method and use its object in the client:
import com.google.gson.JsonParser
val fileContent = MyClass::class.java.getResource("myfile").readText()
println("fileContent string = $fileContent")
var bodyAsJsonObject = JsonParser.parseString(fileContent).asJsonObject
println("bodyAsJsonObject = $bodyAsJsonObject")
val out = client.post<String> {
url(url)
contentType(ContentType.Application.Json)
body = bodyAsJsonObject
}