sending a post request to an external API and extracting data

Question

I wish to mimic the following post request in my code :

curl -v -H "Accept: application/json" \
        -H "Content-type: application/json" \
        -H "App-id: $APP_ID" \
        -H "Secret: $SECRET" \
        -X POST \
        -d "{ \
              \"data\": { \
                \"identifier\": \"test1\" \
              } \
            }" \
        https://www.sampleurl.com/createuser

Ideally the JSON response i would get would be like this

{ "data": { "id": "111", "identifier": "test1", "secret": "SECRET" } }

I am trying to use WebClient to build such a request

WebClient req = WebClient.builder().baseUrl("https://www.sampleurl.com").build();
        String data = "{" + "\n" + "\t" + "\"data\": { \n";
        data += "\t" + "\t" + "\"identifier\": \"" + username + "\"\n";
        data += "\t" + "}" + "\n" + "}";
        body.setIdentifier(username);
        String t = req.post().uri("/createuser")
                      .contentType(MediaType.APPLICATION_JSON)
                      .accept(MediaType.APPLICATION_JSON)
                      .header("App-id", APPID)
                      .header("Secret", SECRET)
                      .body(BodyInserters.fromPublisher(Mono.just(data), String.class))
                      .retrieve()
                      .bodyToMono(String.class)
                      .doOnNext(myString -> {System.out.println(myString);})
                      .block(); 

I am getting the error

org.springframework.web.reactive.function.client.WebClientResponseException$BadRequest: 400 Bad Request

on doing this... Where am I going wrong? Also is there a more efficient way of sending such a request? I am not able to understand how to use Mono properly.

Answer 1

Create the entity class and send that as an object

class RequestPayloadData {
    private String identifier;

    //..getters and setters (or lombok annotation on the class)
}

class RequestPayload {
    private RequestPayloadData data;

    //..getters and setters (or lombok annotation on the class)
}

WebClient req = WebClient.builder().baseUrl("https://www.sampleurl.com").build();
RequestPayload data = new RequestPayload();
data.setData(new RequestPayloadData("test1"));

String t = req.post().uri("/createuser")
              .contentType(MediaType.APPLICATION_JSON)
              .accept(MediaType.APPLICATION_JSON)
              .header("App-id", APPID)
              .header("Secret", SECRET)
              .body(BodyInserters.fromPublisher(Mono.just(data), RequestPayload.class))
              .retrieve()
              .bodyToMono(String.class)
              .doOnNext(myString -> {System.out.println(myString);})
              .block();