Update vertx Json config file during http request

Question

I have VertX application with a config.json file. I want to edit one of the properties in the file during an HTTP request.

Is it possible?

Json Config:

{
  "REQUEST_OPTIONS": {
    "dataFilter": [
      {
        "name": "xxx",
        "values": [1, 2, 3] -> want to edit this specific field!
      },
      {
        "name": "yyy",
        "values": [4, 5, 6]
      }
    ]
  }
}

Start method:

@Override
public void start(Promise<Void> startPromise) {
    CompositeFuture.all(
            //Some other Futures ,
            Future.future(ConfigRetriever.create(vertx)::getConfig)
                    .flatMap(config -> storeData(config)
                            .compose(maybeStoreData -> CompositeFuture.all(
                                    matcherVerticle(subject).apply(maybeStoreData),
                                    http(sharedData, maybeStoreData).apply(config)
                            ))))
            .<Void>mapEmpty()
            .onComplete(startPromise);

Router code:

router.get("/api/action").handler(performAction(configJson));

Action request:

private Handler<RoutingContext> performAction(JsonObject config) {
    return routingContext -> Try.of(() -> Json.decodeValue(routingContext.getBody(), RequestDto.class))
            .onFailure(ex -> log.warn("Failed to process the RequestDto: ", ex))
            .andThen(requestDto -> ???UPDATE CONFIG FILE according to requestDto ???)
            .onFailure(ex -> log.warn("Failed to save request: ", ex))
            .onFailure(ex -> routingContext.response().setStatusCode(HttpResponseStatus.INTERNAL_SERVER_ERROR.code()))
            .onSuccess(handler -> routingContext.response().setStatusCode(HttpResponseStatus.OK.code()));
}

Answer 1

Given that you have your JsonObject already, you can write it to disk using fileSystem().writeFile().

Here's a full example:

Vertx vertx = Vertx.vertx();

var json = new JsonObject("{\n" +
        "  \"REQUEST_OPTIONS\": {\n" +
        "    \"dataFilter\": [\n" +
        "      {\n" +
        "        \"name\": \"xxx\",\n" +
        "        \"values\": [1, 2, 3]" +
        "      },\n" +
        "      {\n" +
        "        \"name\": \"yyy\",\n" +
        "        \"values\": [4, 5, 6]\n" +
        "      }\n" +
        "    ]\n" +
        "  }\n" +
        "}");

json.copy()
    .getJsonObject("REQUEST_OPTIONS")
    // Accessing the dataFilter array
    .getJsonArray("dataFilter")
    // Getting the first element of dataFilter array
    .getJsonObject(0)
    // Accessing the values array
    .getJsonArray("values")
    .add(4);

vertx.fileSystem().writeFile("./new.json", json.toBuffer());