Rust initialize class using reqwest and default headers

I am pretty new in Rust and I am trying to biuld a class to instantiate a client to will get info from an API. My class is like this:

use reqwest::Error;
use reqwest::header::{HeaderMap, HeaderValue, CONTENT_TYPE};
use reqwest::blocking::Client;
use reqwest::header;
use std::env;

struct GateClient {
    host: &'static str,
    prefix: &'static str,
    url: &'static str,
    key: String,
    secret: String,
    client: Client,
}

impl GateClient {
    fn new(key: &str, secret: &str) -> Self {
        let mut headers = header::HeaderMap::new();
        headers.insert(CONTENT_TYPE, HeaderValue::from_static("Accept=application/json"));
        headers.insert(CONTENT_TYPE, HeaderValue::from_static("Content-Type=application/json"));
    
        let client = Client::builder().default_headers(headers).build().unwrap();
        
        GateClient {
            host: "https://api.gateio.ws",
            prefix: "/api/v4",
            url: "/spot/currency_pairs/",
            key: key.to_string(),
            secret: secret.to_string(),
            client,
        }
    }

    fn get(&self, arg: &str) -> Result<String, reqwest::Error> {
        let url = format!("{}{}{}{}", self.host, self.prefix, self.url, arg);
        println!("{}", url);
        let response = self.client.get(&url).send()?;
        response.text()
    }
}

#[tokio::main]
async fn main() -> Result<(), Error> {
    env::set_var("RUST_BACKTRACE", "Full");

    let client = GateClient::new("a", "b");
    let response = client.get("ETH_USDT").unwrap();
    println!("{}", response);

    Ok(())
}

Although, it seems that I have an issue cause my program keeps crashing.

thread ‘main’ panicked at
/home/nicolas/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.36.0/src/runtime/blocking/shutdown.rs:51:21: Cannot drop a runtime in a context where blocking is not allowed. This
happens when a runtime is dropped from within an asynchronous context.
stack backtrace: 0: rust_begin_unwind

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Could someone tell me what’s my error please?

>Solution :

You are not allowed to use reqwest‘s blocking API (or really, any blocking API) inside asynchronous code. Either use all-blocking:

use reqwest::blocking::Client;
use reqwest::header;
use reqwest::header::{HeaderMap, HeaderValue, CONTENT_TYPE};
use reqwest::Error;
use std::env;

struct GateClient {
    host: &'static str,
    prefix: &'static str,
    url: &'static str,
    key: String,
    secret: String,
    client: Client,
}

impl GateClient {
    fn new(key: &str, secret: &str) -> Self {
        let mut headers = header::HeaderMap::new();
        headers.insert(
            CONTENT_TYPE,
            HeaderValue::from_static("Accept=application/json"),
        );
        headers.insert(
            CONTENT_TYPE,
            HeaderValue::from_static("Content-Type=application/json"),
        );

        let client = Client::builder().default_headers(headers).build().unwrap();

        GateClient {
            host: "https://api.gateio.ws",
            prefix: "/api/v4",
            url: "/spot/currency_pairs/",
            key: key.to_string(),
            secret: secret.to_string(),
            client,
        }
    }

    fn get(&self, arg: &str) -> Result<String, reqwest::Error> {
        let url = format!("{}{}{}{}", self.host, self.prefix, self.url, arg);
        println!("{}", url);
        let response = self.client.get(&url).send()?;
        response.text()
    }
}

fn main() -> Result<(), Error> {
    env::set_var("RUST_BACKTRACE", "Full");

    let client = GateClient::new("a", "b");
    let response = client.get("ETH_USDT").unwrap();
    println!("{}", response);

    Ok(())
}

Or all-async:

use reqwest::Client;
use reqwest::header;
use reqwest::header::{HeaderMap, HeaderValue, CONTENT_TYPE};
use reqwest::Error;
use std::env;

struct GateClient {
    host: &'static str,
    prefix: &'static str,
    url: &'static str,
    key: String,
    secret: String,
    client: Client,
}

impl GateClient {
    fn new(key: &str, secret: &str) -> Self {
        let mut headers = header::HeaderMap::new();
        headers.insert(
            CONTENT_TYPE,
            HeaderValue::from_static("Accept=application/json"),
        );
        headers.insert(
            CONTENT_TYPE,
            HeaderValue::from_static("Content-Type=application/json"),
        );

        let client = Client::builder().default_headers(headers).build().unwrap();

        GateClient {
            host: "https://api.gateio.ws",
            prefix: "/api/v4",
            url: "/spot/currency_pairs/",
            key: key.to_string(),
            secret: secret.to_string(),
            client,
        }
    }

    async fn get(&self, arg: &str) -> Result<String, reqwest::Error> {
        let url = format!("{}{}{}{}", self.host, self.prefix, self.url, arg);
        println!("{}", url);
        let response = self.client.get(&url).send().await?;
        response.text().await
    }
}

#[tokio::main]
async fn main() -> Result<(), Error> {
    env::set_var("RUST_BACKTRACE", "Full");

    let client = GateClient::new("a", "b");
    let response = client.get("ETH_USDT").await.unwrap();
    println!("{}", response);

    Ok(())
}