Gatling how to send json body to avoid unmarshal error - scala

Question

I'm trying to send a JSON body to my API using Gatling, but I keep getting error 400 because it cannot unmarshal the body I'm sending:
private val authHeaders = Map(
"Accept" -> "application/json, text/javascript, */*; q=0.01",
"Authorization" -> "Bearer ${access_token}"
)
var requestBody: Body with (Expression[String]) =StringBody("{ \"productId\": " +
product1 + ", \"qty\": "+ 1 +" , \"storeId\": "+ storeId + "}")
var addToCart: ChainBuilder = exec(http("addToCart")
.post(addToCartUrl)
.headers(authHeaders)
.body(requestBody)
.check(bodyString.saveAs("body"))
)
In the Gatling logs I can read that I'm sending this kind of request:
HTTP request:
POST ....
headers:
Accept: application/json, text/javascript, */*; q=0.01
Authorization: Bearer ....
cookie: ROUTE=....
host: .....
content-length: 53
cookies:
ROUTE=...., path=/, secure, HTTPOnly, SameSite=None
body:StringChunksRequestBody{contentType='null', charset=UTF-8, content={ "productId": XXXX, "qty": 1 , "storeId": XXXX}}
I don't think I'm creating the correct body, Is there a way to send only
{ "productId": XXXXX, "qty": 1 , "storeId": XXXXXX} as body?
I might have put the contentType in the wrong way, what is the right order?.

Answer 1

Are you sure product1 and storeId are numbers and not Strings? Otherwise, they must be wrapped with double quotes, which they currently aren't.