Hi ! I would like to know how can I check if there is a response body before reading it For example,...

# ktor

[Distractic]

Hi !
I would like to know how can I check if there is a response body before reading it
For example, from an API, I have this response:

COMMON HEADERS
-> Cache-Control: no-store
-> Content-Length: 0
-> Content-Type: application/json
-> Date: Tue, 21 Nov 2023 21:40:39 GMT
-> Strict-Transport-Security: max-age=31536000; includeSubDomains
BODY Content-Type: application/json
BODY START

BODY END

The body is empty, so when I try to read it, my code throws an exception and I would like to avoid that.

Do you know how can I check if the response has a body or not ?

[Berkay Özkan]

Maybe you can check

call.receiveNullable

[Distractic]

I'm using Ktor as a client and not server.
Also, I'm using a HttpResponseValidator

HttpResponseValidator {
                validateResponse { response ->
                    if (!response.status.isSuccess()) {
                        // Get body here
                    }
                }
            }

[Distractic]

A try catch works of course, but I don't know if there is a better approach

[Berkay Özkan]

Oh sorry i read as request.
is response always null? or depends on condition status code etc

[MV]

capture your response in a Result and check the result

example

suspend fun getNodeInfo(instance: String): Result<NodeInfo> = runCatching {
        lenientKtor
            .get("${constructBaseUrl(instance)}/nodeinfo/2.0.json")
            .body<NodeInfo>()
    }

suspend fun someOther(){
   val node = getNodeInfo(instance)
   if(node.isSuccess) { ... }
}

[Distractic]

The response is arbitrary. With always a different format so that's a bit annoying

Well according to the MV response, I'm supposing that Result / try catch is the only solution

[MV]

It certianly isnt the only solution

With always a different format so that's a bit annoying

what do you mean with that?
Do you mean you always get unkown json structure? You can read the body as a generic JsonObject and parse that

[Distractic]

Exactly, for the moment, I detected three type of response body:
• Nothing (my current question)
•

{data:{error: <message>}}

•

{errors: [list of message]}

[Aleksei Tirman [JB]]

Unfortunately, you cannot determine whether response empty or not without reading it.

[Distractic]

I'm agree with that, but in this case, maybe the bodyAsText should returns empty string instead of throw an illegalStateException 🤔

[Aleksei Tirman [JB]]

Can you share the exception message and stack trace?

[Distractic]

OK I will send that during the day 👍

[Distractic]

Aaah no .. finally I have an empty string .. Well I don't know why yesterday I had an IllegalState