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Rust: How to Make a Network Request

Add this to your Cargo.toml file

[dependencies]
reqwest = { version = "0.11.13", features = ["json"] }
serde_json = "1.0"

If you need to make a synchronous request, use the blocking feature and create a blocking client. JSON is useful when you need to parse a JSON response with something like serde_json::Value or a Struct with the Deserialize derivation.

You should design your code to reuse clients as much as possible. In this code the

use serde_json::Value;
use reqwest;
use reqwest::Client;

// when making requests, try to use an existing client instead of creating a client or using the get method
async fn make_request(client: &Client) &rarr; Result<Value, reqwest::Error> {
    let url = "https://api.sampleapis.com/coffee/hot";
    let response = client.get(url).send().await?;
    let hot_coffees = response.json::<Value>().await;
    hot_coffees
}

// build a client with a user-agent since Client::new does not add a user-agent by default
// use a more sophisticated user-agent if you want to mimic a browser
let client = Client::builder().user_agent("reqwest").build().unwrap();

Making Reqwest Within Rocket Backend

If you want to make outgoing requests while processing an incoming request in Rocket, you may want to use State. Here is an example.

Cargo.toml 
[dependencies]
rocket = { version = "0.5.0-rc.2", features = ["json"] }
reqwest = { version = "0.11.13", features = ["json"] }

use serde_json::Value;
use rocket::State;
use rocket::response::status::NotFound;
use reqwest;
use reqwest::Client;

#[get("/")]
async fn index(client: &State<Client>) &rarr; Result<Value, NotFound<String>> {
    let url = "https://api.sampleapis.com/coffee/hot";
    let response = client.get(url).send().await.map_err(|e| Status::NotFound(e.to_string()))?;
    response.json::<Value>().await.map_err(|e| Status::NotFound(e.to_string()))
    // `result.map_err` is for E &rarr; F whereas `result.or_else` can turn an error into an ok
}

#[launch]
fn rocket() &rarr; _ {
    let client = reqwest::Client::builder().user_agent("reqwest").build().unwrap();
    rocket::build()
        .manage(client)
        .mount("/", routes![index])
}

I also recommend reading json manipulation in Rust.

https://blog.elijahlopez.ca/posts/rust-how-to-make-a-request/ Elijah Lopez