How to pass a json object in OkHttp RequestBody for calling external Apis

@Test
public void whenSendPostRequest_thenCorrect() 
 throws IOException {
    RequestBody formBody = new FormBody.Builder()
        .add("username", "test")
        .add("password", "test")
        .build();

    Request request = new Request.Builder()
        .url(BASE_URL + "/users")
        .post(formBody)
        .build();
    Call call = client.newCall(request);
    Response response = call.execute();
    
    assertThat(response.code(), equalTo(200));
}

Reference - https://www.baeldung.com/guide-to-okhttp

I am trying to execute this type of request where while forming formBody i have to do something like this to have .add("something", json_object) but it accepts a string value and I can't pass json string how to solve this issue

Also json_object is very large so can't just have many .add statements for each key value pair

Suggest you to create a model/pojo class which has the fields same as that in the json string. Then have an object of that class type added to the FormBody class. You can have a json to object mapper to convert the input json to an object of new model class.

So you need the Integration test here. I am using something like this:

TestDto testDto = new TestDto(); //  you need to set the field variables here

given()
	.header(HttpHeaders.AUTHORIZATION, createJwtToken(ADMIN_ID))
	.header(HttpHeaders.ACCEPT, MediaType.APPLICATION_JSON_VALUE)
	.header(HttpHeaders.ACCEPT_LANGUAGE, LANG_EN)
	.contentType(ContentType.JSON)
	.body(objectMapper.writeValueAsString(testDto))
	.when()
		.log().all()
		.post(CONTROLLER_ENDPOINT)
	.then()
		.log().all()
		.statusCode(HttpStatus.CREATED.value())
	.extract()
		.body().as(TestDto.class);

given() will be found in rest-assured.

ObjectMapper is a class that can be found in a jackson library: jackson-databind. createJwtToken() is responsible to give a JWT with the ADADMIN_ID.

Hope, it will help.

After some exploration I found out that we can convert json_string to requestbody json using okhttp Requestbody class create method which takes json mediatype and json_string as parameter and then this body can be passes to .post method of the request builder.

MediaType JSON = MediaType.parse("application/json; charset=utf-8");
RequestBody body = RequestBody.create(JSON, json_string);