Getting error Responder trait not implemented

[sagarnayak]

My Code -

#[macro_use]
extern crate rocket;
extern crate rocket_contrib;

use rand::Rng;
use rocket_contrib::json::Json;
use serde::{Deserialize, Serialize};

#[derive(Serialize, Deserialize)]
pub struct User {
	pub name: String,
}

#[derive(Serialize, Deserialize)]
pub struct StatusMessage {
	pub code: i32,
	pub message: String,
}

#[get("/getJsonResponse")]
fn get_json_response() -> Result<Json<User>, Json<StatusMessage>> {
	let random_result_to_send = rand::thread_rng().gen_bool(1.5);

	if random_result_to_send {
		Ok(
			Json(
				User {
					name: "User name".to_string()
				}
			)
		)
	} else {
		Err(
			Json(
				StatusMessage {
					code: 400,
					message: "got an error".to_string(),
				}
			)
		)
	}
}

#[launch]
fn rocket() -> _ {
	let routes = routes![
		get_json_response
	];
	rocket::build()
		.mount("/", routes)
}

roml -

[package]
name = "web_service"
version = "0.1.0"
edition = "2018"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
rocket = "0.5.0-rc.1"
rand = "0.8.4"
serde = { version = "1.0.64", features = ["derive"] }
serde_json = "1.0.64"
[dependencies.rocket_contrib]
version = "0.4.10"
default-features = false
features = ["json"]

Error -

error[E0277]: the trait bound `rocket_contrib::json::Json<User>: Responder<'_, '_>` is not satisfied
  --> src\main.rs:21:27
   |
21 | fn get_json_response() -> Result<Json<User>, Json<StatusMessage>> {
   |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Responder<'_, '_>` is not implemented for `rocket_contrib::json::Json<User>`
   |
   = note: required because of the requirements on the impl of `Responder<'_, '_>` for `Result<rocket_contrib::json::Json<User>, rocket_contrib::json::Json<StatusMessage>>`
   = note: required by `route::handler::<impl Outcome<rocket::Response<'o>, Status, rocket::Data<'o>>>::from`

error[E0277]: the trait bound `rocket_contrib::json::Json<StatusMessage>: Responder<'_, '_>` is not satisfied
  --> src\main.rs:21:27
   |
21 | fn get_json_response() -> Result<Json<User>, Json<StatusMessage>> {
   |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Responder<'_, '_>` is not implemented for `rocket_contrib::json::Json<StatusMessage>`
   |
   = note: required because of the requirements on the impl of `Responder<'_, '_>` for `Result<rocket_contrib::json::Json<User>, rocket_contrib::json::Json<StatusMessage>>`
   = note: required by `route::handler::<impl Outcome<rocket::Response<'o>, Status, rocket::Data<'o>>>::from`

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0277`.
error: could not compile `web_service`

Do I have to implement the responder my self or I am missing something?

[SergioBenitez]

There is no contrib in 0.5. Please read the CHANGELOG.

[sagarnayak]

This is what i have changed.

[dependencies]
rocket = { version = "0.5.0-rc.1", features = ["json"] }
rand = "0.8.4"
serde = { version = "1.0.64", features = ["derive"] }
serde_json = "1.0.64"

Imports -

#[macro_use]
extern crate rocket;

use rand::Rng;
use serde::{Deserialize, Serialize};
use rocket::serde::json::Json;

Thanks @SergioBenitez its fixed.

[SergioBenitez]

You don't need to depend on serde_json directly. You also don't need to depend on serde at all if you add the following to structs where you derive Serialize or deserialize:

#[serde(crate = "rocket::serde")]

[sagarnayak]

Do you mean I can write like this -

#[serde(crate = "rocket::serde")]
struct User {
	name: String,
}

and i can remote the serde_json = "1.0.64"

[SergioBenitez]

These are independent things. You can remove serde_json full-stop without doing anything else. To remove serde, however, you need to add that attribute wherever you derive Serialize or Deserialize.