Hello, everyone I am using the ktor 1.6.3 client a...

# ktor

[Evgeny Berezovsky]

Hello, everyone
I am using the ktor 1.6.3 client and serialization to send requests
Before that, everything worked correctly, but now I need to send an image to the chat of the application that I am doing
For client settings, defaultRequest uses header(HttpHeaders.ContentType, ContentType.Application.Json)
When sending via submitFormWithBinaryData, it returns the error kotlinx. serialization. SerializationException: Serializer for class 'MultipartFormDataContent' is not found
I tried to change header for the request to send an image with contentType, but I get another error io.ktor. http.UnsafeHeaderException: Header(s) [Content-Type] are controlled by the engine and cannot be set explicitly
Judging by https://youtrack.jetbrains.com/issue/KTOR-620, I can't do this
Setting contentType for MultipartFormDataContent does not give anything

How can I send a request with a serializable class of type AddImageToMessage (val messageId: Int) and attach an image to this request?

[edenman]

need more code to diagnose, but in general, content type is supposed to be set by body

[edenman]

submitFormWithBinaryData looks like it sets the body for you, would need to see what your block is doing

[Evgeny Berezovsky]

if I use the code from the official website.
he doesn't work for me
because defaultRequest is set in header(HttpHeaders.ContentType, ContentType.Application.Json)
I get an error kotlinx. serialization. SerializationException: Serializer for class 'MultipartFormDataContent' is not found

client settings

fun getClient(): HttpClient {

        return HttpClient(CIO) {

            install(JsonFeature) {

                serializer = KotlinxSerializer(

                    Json {
                        prettyPrint = true
                        isLenient = true
                        ignoreUnknownKeys = true
                        coerceInputValues = true
                    }
                )
            }

            expectSuccess = false

            defaultRequest {

                host = BuildConfig.REST_API_ADDRESS
                url.protocol = URLProtocol.HTTPS

                header(HttpHeaders.ContentType, ContentType.Application.Json)
            }
        }
    }

request

suspend fun addImageToMessage(
        messageId: Int,
        path: String,
        image: File
    ) {

        client.submitFormWithBinaryData<Unit>(
            formData = formData {
                append(
                    "image", image.readBytes(), Headers.build {
                        append(HttpHeaders.ContentType, "image/png")
                        append(HttpHeaders.ContentDisposition, "filename=image.png")
                    }
                )
//                append("messageId", messageId)
            }
        ) {
            url.encodedPath = path
//            body = AddImageToMessage(messageId = messageId)
        }
    }

I would also like to add AddImageToMessage to this request
append("messageId", messageId) does not work in my case

[Aleksei Tirman [JB]]

The only thing I can suggest is to not put the application/json content-type in the defaultRequest because this header triggers content converter execution (UnsafeHeaderException is not thrown because because ContentNegotiation removes this header before the check).

[Aleksei Tirman [JB]]

So SerializationException is expectable and to avoid it you should not put the application/json content-type in the first place.

[Evgeny Berezovsky]

I tried this option, but I couldn't add the messageId parameter to the request body
as if I sent them through the serializable AddImageToMessage class
most likely, this should be added to the formData , but I do not know how

[Aleksei Tirman [JB]]

You can serialize it manually and append a string but I agree this is not convenient.

[Evgeny Berezovsky]

please tell me, what value I need to put for the key parameter?

suspend fun addImageToMessage(
        messageId: Int,
        path: String,
        image: File
    ) {

        client.submitFormWithBinaryData<Unit>(
            formData = formData {
                append(
                    "image", image.readBytes(), Headers.build {
                        append(HttpHeaders.ContentType, "image/png")
                        append(HttpHeaders.ContentDisposition, "filename=image.png")
                    }
                )

                val messageIdJson = JSONObject().apply {
                    put("messageId", messageId)
                }

                append(key = "?",value = messageIdJson.toString())
            }
        ) {
            url.encodedPath = path
        }
    }

[Aleksei Tirman [JB]]

@Evgeny Berezovsky, what HTTP request do you want to construct? The key is the name of a part.

[Evgeny Berezovsky]

for example, if I send just a messageId with ContentType=application/json without an attached image, then in the logs it will look like this
but when I attach an image and change ContentType=multipart/form-data, I do not know how to add information about the messageId so that the server sees it

[Evgeny Berezovsky]

an endpoint that I used for request, most likely does not work correctly
I tried another endpoint and it worked
append(key = "messageId",value = messageId) in formData works for me
thank you very much)