Trait for Responder<'_,'_> not satisfied

[aditya-mitra]

I am very new to Rust and I encountered this error while try to build a simple web server using Rocket.

I have the following code:

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

#[derive(Serialize,Deserialize)]
struct NotFound {
    success: bool,
    message: String,
}

#[get("/_/admin", format = "json")]
pub fn index() -> Json<NotFound> {
    Json(NotFound {
        success: false,
        message: String::from("Not Found Custom 404"),
    })
}

On compilation, it gives me the following error:

the trait bound rocket_contrib::json::Json<routes::index_route::NotFound>: rocket::response::Responder<'_, '_> is not satisfied

The dependencies in my cargo.toml are as follows:

[package]
name = "server"
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"
serde = { version = "1.0", features = ["derive"] }
serde_json = "1.0"

[dependencies.rocket_contrib]
version = "*"
default-features = false
features = ["json"]

Can somebody please help me with what mistake I am making?

[jebrosen]

This looks like a duplicate of #1779 and a few others. Please see the CHANGELOG, especially regarding the removal of rocket_contrib: https://github.com/SergioBenitez/Rocket/blob/v0.5-rc/CHANGELOG.md#contrib-graduation.

(Incidentally, version = "*" is rarely a good choice for Cargo.toml. Among other issues, it allows cargo update to either update or downgrade that dependency on a whim, likely breaking your code that uses it.)

[aditya-mitra]

Thanks a lot @jebrosen

I did not notice I had to use features = ["json"] and include the serde library as well in documentation example

Also thanks for the tip 🥇

I referred to many blogs and videos before posting this question. All the results which even appear on the top of search use rocket_contrib. They are outdated. I will write a blog post once I get a very good grasp of Rust. 😃

[JoshuaNitschke]

I found the documentation hard to follow as well, which is why I am here. I think an example Cargo.toml file showing what needs to be set up to successfully configure JSON would be helpful in the documentation.