Ktor Post Json Body, For eg I get status code 400 and the following body - { " Manually parsing incoming data and building a JSON string for every response is not ideal. ) allow you to receive a response as an HttpResponse object. 4 Firstly, ContentNegotiation feature works only for receiving custom objects from the payload of POST, PUT and PATCH requests: POST, PUT and PATCH requests have an associated request body (the payload). This tutorial covers:Setting up Ktor dependenciesMaking GET and POST requests with POST, PUT and PATCH POST, PUT and PATCH requests has an associated request body (the payload). post ("$ {BASE_URL}/following") { contentType (ContentType. Raw Form parameters Ktor allows you to receive form parameters sent with both x-www-form-urlencoded and multipart/form-data types using the receiveParameters function. encodeToString(requestBody) to see wether it's the string you expect to send, or just add install(Logging) { level = LogLevel. annotations or HttpRequestBuilder. Serialization allows us to parse incoming request bodies and generate response bodies as classes seamlessly. post< Reading data from call. I am new to Ktor and I have a route with a request body which i am parsing with Kotlin Serialization. But before we start actual coding, lets 3 For the Ktor http client to deserialize to your custom object, you would need to install JsonFeature while creating your http client, which would need the io. Ktor can be used as a HTTP client or you can build servers with it. 3 fwiw I use something like following here. Jan 23, 2026 · To receive a raw body of a response, call the body function and pass the required type as a parameter. I use IDEA to generate a template and notice that runBlocking in Application. The validate function has two overloads allowing you to validate a request body in two ways: The first validate overload allows you to access a request body as the Create simple POST request with ktor In this tutorial we will create our first POST-Route in ktor and test it. Learn how to correctly catch JSON data from the request body in Ktor with this straightforward guide. In order to receive custom objects from the payload, you have to use the ContentNegotiation feature. Recently I had a problem, where I should get the last successful build hash of a Jenkins Job. How can I post file as multipart/form-data use ktor client? I want to use it for telegram bot API "send document". Ktor is a powerful Kotlin-based framework for building asynchronous servers and clients, and i If you need to send a file with a form, you can use the following approaches: Use the . kotlinx. Once set up, it works automatically without requiring manual intervention. module like: runBlocking { // Sample for making a HTTP Client request val message = client. serialization: serialize/deserialize JSON (and other formats if needed). Json) that sends the Content-Type header with application/json value. In this tutorial, we will explore how to use Ktor Android Client to make all types of HTTP requests including GET, POST, PUT, DELETE, and form submissions. To do this, pass a class instance to the setBody() function and set the content type to application/json using the contentType() function: Jan 13, 2021 · The solution is to pass to the HTTP POST request a JSON object not a String object. Jun 26, 2021 · With this I get an Error 500. Note that serializers for specific formats require additional artifacts. They look the same when you print them, but of course they are not equally interpreted by the JVM. Then, you can use the call. but i am not clear how to do that. Discover essential code adjustments to handle your POST However, when I use ktor-client to serialize my object, it complains that LoginRequestVo is not serializable. though I would have thought specifying url like you do should also work. This tutorial covers setup, routing, and testing on a real-life example. Is there a complete documentation? According to this, I need to use httpClient. The call. This causes the SerializationException because the JsonFeature tries to serialize MultiPartFormDataContent object. Inside, it tries to receive the json body and map it to RouteSignalNotificationResponse data class. This route handles the POST requests received to the path “/products”. Special in this case is that we want to specify parameters and use them then in the reponse. payload expression is type LoginRequest as I want to see the json result of the body but I have no idea how, I am recieving a 400 bad request and I am pretty sure the issue comes from "listOf . submitFormWithBinaryData() function. In this case, a boundary will be generated automatically. For both approaches, you need to To enable serialization of data objects in Ktor, you need to install the ContentNegotiation plugin and register a required converter (for example, JSON). ) and obtain response parameters, such as a status code, content type, and headers. receive<Product>() function deserializes the JSON data in the request body into a Product object. So I am receiving the data but call. The example code below uses some other objects from my project and has more information that you need, but the gist is that the type of U in the invoke function and therefore the request. Empty So what's the kotlin/ktor Serialize JSON HttpResponse to Kotlin Objects with Ktor. serialization requires the ktor-serialization-kotlinx-json dependency for JSON. example. how can I do this? I wrote this code but it's not working: override suspend fun Content Negotiation: converts request body based on the content type header. string to get the response object as a string, you could then get single JSON keys and their corresponding values. They give a nice example of how to test a GET endpoint here, however I'm having trouble with an http POST. Simplified explanations and code Please note that some of response types are Closeable and can hold resources. Add Features using Ktor Modules Ktor uses modules to encapsulate specific features for example serialization and routing can be added to the application like so: I am building a server using the Ktor framework in Kotlin. This function returns a ValidationResult object representing a successful or unsuccessful validation result. You have the line contentType(ContentType. That payload is usually encoded. I'm trying to send a POST request with a body and I'm facing off the following error: Learn how to set up and use the Ktor HTTP Client for API calls in Kotlin. You already know how to make simple requests to the server using Ktor Client and get the code and re Learn to build Kotlin RESTful APIs with Ktor. HttpResponse exposes the API required to get a response body in various ways (raw bytes, JSON objects, etc. I have a post request done with Ktor this way val response = httpClient. respond() function to pass a data object in a response: Try to log Json. The app has a POST route used for processing HTTP POST requests. For this I used a simple json api call via Learn how to use Ktor Client for HTTP requests in Android, explore its engine plugin, customization options, and see a real-world app demo. Ktor is built from the ground up using Kotlin and Coroutines. Parse and generate JSON efficiently with Ktor. receiveChannel () does show correct JSON. Thank you Aleksei, I have the JsonFeature enabled, so ktor created a json-string out of a json-string :D Thanks for pointing me to the right driectionproblem solved. Ktor Version and Engine Used 1. 接收响应的 body 默认情况下，可以使用 HttpResponse 或者 String 作为类型化 HttpClient 请求的类型。例如： With retrofit, you can use response. anyone please help me. Oct 24, 2025 · Body contents This section shows how to receive body contents sent with POST, PUT, or PATCH. ALL } for your client. serialization JsonFeature for both Android and iOS. I need to achieve the same result as the curl command curl -F document=@ Getting Started with REST API in Android using Ktor Introduction In the world of Android development, working with REST APIs is a common and essential task. I tested #1 and #3 and because I like challenges from I BODY END This is my first time using Ktor because i need to use it. For both approaches, you need to We are sending a post request using Ktor. This means that the input data is parsed into an internal form as it is being read, and avoids the need to allocate How do I send json in form data from the ktor client and receive it on a ktor server? I need multiple keys (json and json2) with json data in them in the same request. 40), Server (Netty) Describe the bug Making an HTTP POST request without (empty request bodies work fine) a request body crashes content negotiation. receive () does not seem to produce expected results. Uploading multipart form data using Ktor In this tutorial, we will learn how to make multipart form data post calls to upload files and Http form data. request. Streamline your Kotlin backend development with powerful serialization capabilities. The code works when I define four data clas I have an api that returns error body with the correct error information when a bad request is sent. 3 (Kotlin 1. To validate a request body, use the validate function. Sep 18, 2020 · In this article you will learn how to create a post route which receives json, does some logic with the content of the json and returns json content to the executor. The RequestBuilder will be applied last after everything that is set by Ktorfit Annotations Function annotations are available in the request object with their respective values via the annotation extension (HttpRequest. This library provides ktor client interface integration for the json-kotlin library. 如何使用kotlin和ktor在POST请求中添加JSON字符串？ 打印出从文件中读取的JSON字符串，甚至在客户端使用Kotlin构造字符串，内容看起来像Json。 尽管如此，服务器不能将字符串识别为JSON，并且当我在服务器中打印它时，每个双倍配额都被反斜杠。 Learn how to effectively specify body parameters like "email" and "password" when sending POST requests using `Ktor Client`. Jan 20, 2026 · With the enabled ContentNegotiation plugin, you can send a class instance within a request body as JSON. annotations) Do note that OptIn and Ktorfit annotations are not I'm using ktor-client in a Kotlin Multiplatform project, using kotlinx. Ktor is a framework for building asnchronous servers with the kotlin programming … I'm getting the following error, when I try to make a post request to my django rest API with ktor Error: Fail to serialize body. 2 onwards, this library uses the json-streaming library for on-the-fly JSON parsing. You get to use a concise, multiplatform language, as well as the Ktor — full type safe json api with endpoint definitions Ktor Endpoints One nice thing of using Ktor is that you can share some code between the server app, and the client -with KMP it can be a … This api works perfectly in postman when i pass the form-data in body tab. Learn the fundamentals of validation, error handling, and unit testing for services created with Kotlin and Ktor. It’s an ideal entry-level tutorial for Kotlin backend developers. Json) setBody (UnfollowRequestBody (userId, Ktor: POST request with parameters In this tutorial we will create another POST-Route. I am currently writing a test for my API route that registers a user, but I keep encountering an error when I attempt to send a JSON body All functions used to make an HTTP request (request, get, post, etc. Looks like something is wrong with the body data but I checked same string in Python and all is ok there. 2. The example below shows an HTTP client POST request with form parameters passed in a body: I want to call an API with the body and send two parameters to this request in the android ktor client. Hello, I’m trying to upload a JSON file with a PUT method. Ktor (kotlin web framework) has an awesome testable mode where http requests can be wrapped in unit tests. After upgrading to V1. Thankfully, there’s a solution: Serialization. u I am working on an Android app that uses Ktor for HTTP requests to an API. To achieve this is in Ktor, use response Then you can use the extension function to set additional configuration. Depending upon the query, the response may contain a list of one of two types. Application. Dec 5, 2024 · This article aims to guide you through making GET and POST requests with Ktor client, which is a powerful and flexible HTTP client library that is suitable for both Android applications and web server applications. The MultiPartFormDataContent constructor also allows you to pass a boundary value. For an unsuccessful result, RequestValidationException is raised. Idk why Ktor getting response body from request instead of response, the first one is null (black space between BODY START and BODY END) and the 2nd one is not null with message "User already logged in!", and i need to get the 2nd one. The code snippet below shows how to receive a raw body as a String: If you need to send a file with a form, you can use the following approaches: Use the . i read the ktor documentation mentioned about that Here. Content has type: class com. I know that the request body is expected to conform to the request body data class but then, I tested by passing the wrong field in my test payload and it crashed the app. watchwithmemobile. But can’t find the proper way to do this. domain. 3. submitFormWithBinaryData but can’t find how to change the default POST method. Depending on the included artifacts, Ktor chooses a default serializer automatically. For example, kotlinx. dto. REST APIs allow your Android app to … As part of my series “An opinionated Kotlin backend service”, I was checking out different ways to serialize/deserialize JSON payloads. ktor:ktor-client-json dependency added. I've found nearly everywhere in ktor-client documentation and examples they use empty formData to show how the client works formParameters: Parameters = Parameters. From version 0. If required, you can specify the serializer explicitly and configure it. Customizing requests 我们不能只进行 get 请求，Ktor 允许使用任何 HTTP 动词构件复杂请求，并且灵活地以多种方式处理响应。 Default http methods 与 request 类似，还有几个可以 使用最常见的 HTTP 动词（GET 、 POST 、 PUT 、 DELETE 、 PATCH 、 HEAD 以及 OPTIONS Note that serializers for specific formats require additional artifacts. but i don't know how to do that here in ktor. Call the post function and pass the MultiPartFormDataContent instance to the setBody function. All the receive methods consume the whole payload sent by the client so an attempt to receive a request body twice will lead to RequestAlreadyConsumedException error unless you have DoubleReceive feature installed. 2 to support kotlin 1. 7, the request body started showing empty and nothing is actually sent in the body. What issue do you see? The body might also be some json for example, or maybe a data class etc if you have serialization setup. rvawu, jvtn, 2msz12, vda0w, tttoxq, ydawb, tsmkdu, umonl, gvkx0, bkys,