Related
I am trying to use hyper to grab the content of an HTML page and would like to synchronously return the output of a future. I realized I could have picked a better example since synchronous HTTP requests already exist, but I am more interested in understanding whether we could return a value from an async calculation.
extern crate futures;
extern crate hyper;
extern crate hyper_tls;
extern crate tokio;
use futures::{future, Future, Stream};
use hyper::Client;
use hyper::Uri;
use hyper_tls::HttpsConnector;
use std::str;
fn scrap() -> Result<String, String> {
let scraped_content = future::lazy(|| {
let https = HttpsConnector::new(4).unwrap();
let client = Client::builder().build::<_, hyper::Body>(https);
client
.get("https://hyper.rs".parse::<Uri>().unwrap())
.and_then(|res| {
res.into_body().concat2().and_then(|body| {
let s_body: String = str::from_utf8(&body).unwrap().to_string();
futures::future::ok(s_body)
})
}).map_err(|err| format!("Error scraping web page: {:?}", &err))
});
scraped_content.wait()
}
fn read() {
let scraped_content = future::lazy(|| {
let https = HttpsConnector::new(4).unwrap();
let client = Client::builder().build::<_, hyper::Body>(https);
client
.get("https://hyper.rs".parse::<Uri>().unwrap())
.and_then(|res| {
res.into_body().concat2().and_then(|body| {
let s_body: String = str::from_utf8(&body).unwrap().to_string();
println!("Reading body: {}", s_body);
Ok(())
})
}).map_err(|err| {
println!("Error reading webpage: {:?}", &err);
})
});
tokio::run(scraped_content);
}
fn main() {
read();
let content = scrap();
println!("Content = {:?}", &content);
}
The example compiles and the call to read() succeeds, but the call to scrap() panics with the following error message:
Content = Err("Error scraping web page: Error { kind: Execute, cause: None }")
I understand that I failed to launch the task properly before calling .wait() on the future but I couldn't find how to properly do it, assuming it's even possible.
Standard library futures
Let's use this as our minimal, reproducible example:
async fn example() -> i32 {
42
}
Call executor::block_on:
use futures::executor; // 0.3.1
fn main() {
let v = executor::block_on(example());
println!("{}", v);
}
Tokio
Use the tokio::main attribute on any function (not just main!) to convert it from an asynchronous function to a synchronous one:
use tokio; // 0.3.5
#[tokio::main]
async fn main() {
let v = example().await;
println!("{}", v);
}
tokio::main is a macro that transforms this
#[tokio::main]
async fn main() {}
Into this:
fn main() {
tokio::runtime::Builder::new_multi_thread()
.enable_all()
.build()
.unwrap()
.block_on(async { {} })
}
This uses Runtime::block_on under the hood, so you can also write this as:
use tokio::runtime::Runtime; // 0.3.5
fn main() {
let v = Runtime::new().unwrap().block_on(example());
println!("{}", v);
}
For tests, you can use tokio::test.
async-std
Use the async_std::main attribute on the main function to convert it from an asynchronous function to a synchronous one:
use async_std; // 1.6.5, features = ["attributes"]
#[async_std::main]
async fn main() {
let v = example().await;
println!("{}", v);
}
For tests, you can use async_std::test.
Futures 0.1
Let's use this as our minimal, reproducible example:
use futures::{future, Future}; // 0.1.27
fn example() -> impl Future<Item = i32, Error = ()> {
future::ok(42)
}
For simple cases, you only need to call wait:
fn main() {
let s = example().wait();
println!("{:?}", s);
}
However, this comes with a pretty severe warning:
This method is not appropriate to call on event loops or similar I/O situations because it will prevent the event loop from making progress (this blocks the thread). This method should only be called when it's guaranteed that the blocking work associated with this future will be completed by another thread.
Tokio
If you are using Tokio 0.1, you should use Tokio's Runtime::block_on:
use tokio; // 0.1.21
fn main() {
let mut runtime = tokio::runtime::Runtime::new().expect("Unable to create a runtime");
let s = runtime.block_on(example());
println!("{:?}", s);
}
If you peek in the implementation of block_on, it actually sends the future's result down a channel and then calls wait on that channel! This is fine because Tokio guarantees to run the future to completion.
See also:
How can I efficiently extract the first element of a futures::Stream in a blocking manner?
As this is the top result that come up in search engines by the query "How to call async from sync in Rust", I decided to share my solution here. I think it might be useful.
As #Shepmaster mentioned, back in version 0.1 futures crate had beautiful method .wait() that could be used to call an async function from a sync one. This must-have method, however, was removed from later versions of the crate.
Luckily, it's not that hard to re-implement it:
trait Block {
fn wait(self) -> <Self as futures::Future>::Output
where Self: Sized, Self: futures::Future
{
futures::executor::block_on(self)
}
}
impl<F,T> Block for F
where F: futures::Future<Output = T>
{}
After that, you can just do following:
async fn example() -> i32 {
42
}
fn main() {
let s = example().wait();
println!("{:?}", s);
}
Beware that this comes with all the caveats of original .wait() explained in the #Shepmaster's answer.
This works for me using tokio:
tokio::runtime::Runtime::new()?.block_on(fooAsyncFunction())?;
How can I make an HTTP request from Rust? I can't seem to find anything in the core library.
I don't need to parse the output, just make a request and check the HTTP response code.
Bonus marks if someone can show me how to URL encode the query parameters on my URL!
The easiest way to make HTTP requests in Rust is with the reqwest crate:
use std::error::Error;
fn main() -> Result<(), Box<dyn Error>> {
let resp = reqwest::blocking::get("https://httpbin.org/ip")?.text()?;
println!("{:#?}", resp);
Ok(())
}
In Cargo.toml:
[dependencies]
reqwest = { version = "0.11", features = ["blocking"] }
Async
Reqwest also supports making asynchronous HTTP requests using Tokio:
use std::error::Error;
#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
let resp = reqwest::get("https://httpbin.org/ip")
.await?
.text()
.await?;
println!("{:#?}", resp);
Ok(())
}
In Cargo.toml:
[dependencies]
reqwest = "0.11"
tokio = { version = "1", features = ["full"] }
Hyper
Reqwest is an easy to use wrapper around Hyper, which is a popular HTTP library for Rust. You can use it directly if you need more control over managing connections. A Hyper-based example is below and is largely inspired by an example in its documentation:
use hyper::{body::HttpBody as _, Client, Uri};
use std::error::Error;
#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
let client = Client::new();
let res = client
.get(Uri::from_static("http://httpbin.org/ip"))
.await?;
println!("status: {}", res.status());
let buf = hyper::body::to_bytes(res).await?;
println!("body: {:?}", buf);
}
In Cargo.toml:
[dependencies]
hyper = { version = "0.14", features = ["full"] }
tokio = { version = "1", features = ["full"] }
Original answer (Rust 0.6)
I believe what you're looking for is in the standard library. now in rust-http and Chris Morgan's answer is the standard way in current Rust for the foreseeable future. I'm not sure how far I can take you (and hope I'm not taking you the wrong direction!), but you'll want something like:
// Rust 0.6 -- old code
extern mod std;
use std::net_ip;
use std::uv;
fn main() {
let iotask = uv::global_loop::get();
let result = net_ip::get_addr("www.duckduckgo.com", &iotask);
io::println(fmt!("%?", result));
}
As for encoding, there are some examples in the unit tests in src/libstd/net_url.rs.
Update: This answer refers to fairly ancient history. For the current best practices, please look at Isaac Aggrey's answer instead.
I've been working on rust-http, which has become the de facto HTTP library for Rust (Servo uses it); it's far from complete and very poorly documented at present. Here's an example of making a request and doing something with the status code:
extern mod http;
use http::client::RequestWriter;
use http::method::Get;
use http::status;
use std::os;
fn main() {
let request = RequestWriter::new(Get, FromStr::from_str(os::args()[1]).unwrap());
let response = match request.read_response() {
Ok(response) => response,
Err(_request) => unreachable!(), // Uncaught condition will have failed first
};
if response.status == status::Ok {
println!("Oh goodie, I got me a 200 OK response!");
} else {
println!("That URL ain't returning 200 OK, it returned {} instead", response.status);
}
}
Run this code with a URL as the sole command-line argument and it'll check the status code! (HTTP only; no HTTPS.)
Compare with src/examples/client/client.rs for an example that does a little more.
rust-http is tracking the master branch of rust. At present it'll work in the just-released Rust 0.8, but there are likely to be breaking changes soon. Actually, no version of rust-http works on Rust 0.8—there was a breaking change which can't be worked around in privacy rules just before the release, leaving something that rust-http depends on in extra::url inaccessible. This has since been fixed, but it leaves rust-http incompatible with Rust 0.8.
As for the query string encoding matter, at present that should be done with extra::url::Query (a typedef for ~[(~str, ~str)]). Appropriate functions for conversions:
extra::url::query_to_str
extra::url::query_from_str (sorry, can't use this just at present as it's private. PR to make it public about to come. In the mean time, this link actually shouldn't work, it's only available because of https://github.com/mozilla/rust/issues/7476.)
Using curl bindings. Stick this in your Cargo.toml:
[dependencies.curl]
git = "https://github.com/carllerche/curl-rust"
...and this in the src/main.rs:
extern crate curl;
use curl::http;
fn main(){
let resp = http::handle()
.post("http://localhost:3000/login", "username=dude&password=sikrit")
.exec().unwrap();
println!("code={}; headers={}; body={}",
resp.get_code(), resp.get_headers(), resp.get_body());
}
I prefer Crates with low dependency count, so I would recommend these:
MinReq (0 deps)
use minreq;
fn main() -> Result<(), minreq::Error> {
let o = minreq::get("https://speedtest.lax.hivelocity.net").send()?;
let s = o.as_str()?;
print!("{}", s);
Ok(())
}
HTTP_Req (35 deps)
use {http_req::error, http_req::request, std::io, std::io::Write};
fn main() -> Result<(), error::Error> {
let mut a = Vec::new();
request::get("https://speedtest.lax.hivelocity.net", &mut a)?;
io::stdout().write(&a)?;
Ok(())
}
To elaborate on Isaac Aggrey's answer, here's an example of making a POST request with query parameters using the reqwest library.
Cargo.toml
[package]
name = "play_async"
version = "0.1.0"
edition = "2018"
[dependencies]
reqwest = "0.10.4"
tokio = { version = "0.2.21", features = ["macros"] }
Code
use reqwest::Client;
type Error = Box<dyn std::error::Error>;
type Result<T, E = Error> = std::result::Result<T, E>;
async fn post_greeting() -> Result<()> {
let client = Client::new();
let req = client
// or use .post, etc.
.get("https://webhook.site/1dff66fd-07ff-4cb5-9a77-681efe863747")
.header("Accepts", "application/json")
.query(&[("hello", "1"), ("world", "ABCD")]);
let res = req.send().await?;
println!("{}", res.status());
let body = res.bytes().await?;
let v = body.to_vec();
let s = String::from_utf8_lossy(&v);
println!("response: {} ", s);
Ok(())
}
#[tokio::main]
async fn main() -> Result<()> {
post_greeting().await?;
Ok(())
}
Go to https://webhook.site and create your webhook link and change the code to match. You'll see the request was received on server in realtime.
This example was originally based on Bastian Gruber's example and has been updated for modern Rust syntax and newer crate versions.
Building upon Patrik Stas' answer, if you want to do an HTTP form URL-encoded POST, here is what you have to do. In this case, it's to get an OAuth client_credentials token.
Cargo.toml
[dependencies]
reqwest = "0.10.4"
tokio = { version = "0.2.21", features = ["macros"] }
Code
use reqwest::{Client, Method};
type Error = Box<dyn std::error::Error>;
type Result<T, E = Error> = std::result::Result<T, E>;
async fn print_access_token() -> Result<()> {
let client = Client::new();
let host = "login.microsoftonline.com";
let tenant = "TENANT";
let client_id = "CLIENT_ID";
let client_secret = "CLIENT_SECRET";
let scope = "https://graph.microsoft.com/.default";
let grant_type = "client_credentials";
let url_string = format!("https://{}/{}/oauth2/v2.0/token", host, tenant);
let body = format!(
"client_id={}&client_secret={}&scope={}&grant_type={}",
client_id, client_secret, scope, grant_type,
);
let req = client.request(Method::POST, &url_string).body(body);
let res = req.send().await?;
println!("{}", res.status());
let body = res.bytes().await?;
let v = body.to_vec();
let s = String::from_utf8_lossy(&v);
println!("response: {} ", s);
Ok(())
}
#[tokio::main]
async fn main() -> Result<()> {
print_access_token().await?;
Ok(())
}
This will print something like the following.
200 OK
response: {"token_type":"Bearer","expires_in":3599,"ext_expires_in":3599,"access_token":"ACCESS_TOKEN"}
Dropping a version here that uses the surf crate (dual to the tide crate):
let res = surf::get("https://httpbin.org/get").await?;
assert_eq!(res.status(), 200);
Using hyper "0.13"
Also using hyper-tls for HTTPS support.
File Cargo.toml
hyper = "0.13"
hyper-tls = "0.4.1"
tokio = { version = "0.2", features = ["full"] }
Code
extern crate hyper;
use hyper::Client;
use hyper::body::HttpBody as _;
use tokio::io::{stdout, AsyncWriteExt as _};
use hyper_tls::HttpsConnector;
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
// HTTP only
// let client = Client::new();
// http or https connections
let client = Client::builder().build::<_, hyper::Body>(HttpsConnector::new());
let mut resp = client.get("https://catfact.ninja/fact".parse()?).await?;
println!("Response: {}", resp.status());
while let Some(chunk) = resp.body_mut().data().await {
stdout().write_all(&chunk?).await?;
}
Ok(())
}
Adapted from https://hyper.rs/guides/client/basic/
Simple http request with this crate: wsd
fn test() {
wsd::http::get("https://docs.rs/", |data| {
println!("status = {}, data = {}", data.status(), data.text());
});
}
I'm trying to use async_std to receive UDP datagrams from the network.
There is a UdpSocket that implements async recv_from, this method returns a future but I need a async_std::stream::Stream that gives a stream of UDP datagrams because it is a better abstraction.
I've found tokio::net::UdpFramed that does exactly what I need but it is not available in current versions of tokio.
Generally speaking the question is how do I convert Futures from a given async function into a Stream?
For a single item, use FutureExt::into_stream:
use futures::prelude::*; // 0.3.1
fn outer() -> impl Stream<Item = i32> {
inner().into_stream()
}
async fn inner() -> i32 {
42
}
For a stream from a number of futures generated by a closure, use stream::unfold:
use futures::prelude::*; // 0.3.1
fn outer() -> impl Stream<Item = i32> {
stream::unfold((), |()| async { Some((inner().await, ())) })
}
async fn inner() -> i32 {
42
}
In your case, you can use stream::unfold:
use async_std::{io, net::UdpSocket}; // 1.4.0, features = ["attributes"]
use futures::prelude::*; // 0.3.1
fn read_many(s: UdpSocket) -> impl Stream<Item = io::Result<Vec<u8>>> {
stream::unfold(s, |s| {
async {
let data = read_one(&s).await;
Some((data, s))
}
})
}
async fn read_one(s: &UdpSocket) -> io::Result<Vec<u8>> {
let mut data = vec![0; 1024];
let (len, _) = s.recv_from(&mut data).await?;
data.truncate(len);
Ok(data)
}
#[async_std::main]
async fn main() -> io::Result<()> {
let s = UdpSocket::bind("0.0.0.0:9876").await?;
read_many(s)
.for_each(|d| {
async {
match d {
Ok(d) => match std::str::from_utf8(&d) {
Ok(s) => println!("{}", s),
Err(_) => println!("{:x?}", d),
},
Err(e) => eprintln!("Error: {}", e),
}
}
})
.await;
Ok(())
}
Generally speaking the question is how do I convert Futures from a given async function into a Stream?
There is FutureExt::into_stream, but don't let the name fool you; it is not a good fit for your situation.
There is a UdpSocket that implements async recv_from, this method returns a future but I need a async_std::stream::Stream that gives a stream of UDP datagrams because it is a better abstraction.
It is not necessarily a better abstraction here.
Specifically, async-std's UdpSocket::recv_from returns a future that has output type of (usize, SocketAddr) — the size of the data received and the peer address. If you were to use into_stream to convert it to a stream, it would give you just that, not the data received.
I've found tokio::net::UdpFramed that does exactly what I need but it is not available in current versions of tokio.
It has been moved to tokio-util crate. Unfortunately, you can't (easily) use that either. It requires a tokio::net::UdpSocket, which is not the same as async_std::net::UdpSocket.
You can, of course, use futures utility functions such as futures::stream::poll_fn or futures::stream::unfold to give UdpSocket::recv_from a futures::stream::Stream facade, but then what will you do with that? If you end up calling StreamExt::next to poll a value out of it, you could have used recv_from directly.
It is only necessary to reach for Stream if some API you are using requires a Stream input, such as rusoto:
Is it possible to create a Stream from a File rather than loading the file contents into memory?
I have a concept project where the client sends a server a number (PrimeClientRequest), the server computes if the value is prime or not, and returns a response (PrimeClientResponse). I want the client to be a simple CLI which prompts the user for a number, sends the request to the server, and displays the response. Ideally I want to do this using TcpClient from Tokio and Streams from Futures-Rs.
I've written a Tokio server using services and I want to reuse the same codec and proto for the client.
Part of the client is a function called read_prompt which returns a Stream. Essentially it is an infinite loop at which each iteration reads in some input from stdin.
Here's the relevant code:
main.rs
use futures::{Future, Stream};
use std::env;
use std::net::SocketAddr;
use tokio_core::reactor::Core;
use tokio_prime::protocol::PrimeClientProto;
use tokio_prime::request::PrimeRequest;
use tokio_proto::TcpClient;
use tokio_service::Service;
mod cli;
fn main() {
let mut core = Core::new().unwrap();
let handle = core.handle();
let addr_string = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
let remote_addr = addr_string.parse::<SocketAddr>().unwrap();
println!("Connecting on {}", remote_addr);
let tcp_client = TcpClient::new(PrimeClientProto).connect(&remote_addr, &handle);
core.run(tcp_client.and_then(|client| {
client
.call(PrimeRequest { number: Ok(0) })
.and_then(|response| {
println!("RESP = {:?}", response);
Ok(())
})
})).unwrap();
}
cli.rs
use futures::{Future, Sink, Stream};
use futures::sync::mpsc;
use std::{io, thread};
use std::io::{Stdin, Stdout};
use std::io::prelude::*;
pub fn read_prompt() -> impl Stream<Item = u64, Error = ()> {
let (tx, rx) = mpsc::channel(1);
thread::spawn(move || loop {
let thread_tx = tx.clone();
let input = prompt(io::stdout(), io::stdin()).unwrap();
let parsed_input = input
.parse::<u64>()
.map_err(|_| io::Error::new(io::ErrorKind::Other, "invalid u64"));
thread_tx.send(parsed_input.unwrap()).wait().unwrap();
});
rx
}
fn prompt(stdout: Stdout, stdin: Stdin) -> io::Result<String> {
let mut stdout_handle = stdout.lock();
stdout_handle.write(b"> ")?;
stdout_handle.flush()?;
let mut buf = String::new();
let mut stdin_handle = stdin.lock();
stdin_handle.read_line(&mut buf)?;
Ok(buf.trim().to_string())
}
With the code above, the client sends a single request to the server before the client terminates. I want to be able to use the stream generated from read_prompt to provide input to the TcpClient and make a request per item in the stream. How would I go about doing this?
The full code can be found at joshleeb/tokio-prime.
The solution I have come up with (so far) has been to use the LoopFn in the Future-Rs crate. It's not ideal as a new connection still has to be made but it is at least a step in the right direction.
main.rs
use futures::{future, Future};
use std::{env, io};
use std::net::SocketAddr;
use tokio_core::reactor::{Core, Handle};
use tokio_prime::protocol::PrimeClientProto;
use tokio_prime::request::PrimeRequest;
use tokio_proto::TcpClient;
use tokio_service::Service;
mod cli;
fn handler<'a>(
handle: &'a Handle, addr: &'a SocketAddr
) -> impl Future<Item = (), Error = ()> + 'a {
cli::prompt(io::stdin(), io::stdout())
.and_then(move |number| {
TcpClient::new(PrimeClientProto)
.connect(addr, handle)
.and_then(move |client| Ok((client, number)))
})
.and_then(|(client, number)| {
client
.call(PrimeRequest { number: Ok(number) })
.and_then(|response| {
println!("{:?}", response);
Ok(())
})
})
.or_else(|err| {
println!("! {}", err);
Ok(())
})
}
fn main() {
let mut core = Core::new().unwrap();
let handle = core.handle();
let addr_string = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
let remote_addr = addr_string.parse::<SocketAddr>().unwrap();
println!("Connecting on {}", remote_addr);
let client = future::loop_fn((), |_| {
handler(&handle, &remote_addr)
.map(|_| -> future::Loop<(), ()> { future::Loop::Continue(()) })
});
core.run(client).ok();
}
cli.rs
use futures::prelude::*;
use std::io;
use std::io::{Stdin, Stdout};
use std::io::prelude::*;
#[async]
pub fn prompt(stdin: Stdin, stdout: Stdout) -> io::Result<u64> {
let mut stdout_handle = stdout.lock();
stdout_handle.write(b"> ")?;
stdout_handle.flush()?;
let mut buf = String::new();
let mut stdin_handle = stdin.lock();
stdin_handle.read_line(&mut buf)?;
parse_input(buf.trim().to_string())
}
fn parse_input(s: String) -> io::Result<u64> {
s.parse::<u64>()
.map_err(|_| io::Error::new(io::ErrorKind::Other, "invalid u64"))
}
How can I make an HTTP request from Rust? I can't seem to find anything in the core library.
I don't need to parse the output, just make a request and check the HTTP response code.
Bonus marks if someone can show me how to URL encode the query parameters on my URL!
The easiest way to make HTTP requests in Rust is with the reqwest crate:
use std::error::Error;
fn main() -> Result<(), Box<dyn Error>> {
let resp = reqwest::blocking::get("https://httpbin.org/ip")?.text()?;
println!("{:#?}", resp);
Ok(())
}
In Cargo.toml:
[dependencies]
reqwest = { version = "0.11", features = ["blocking"] }
Async
Reqwest also supports making asynchronous HTTP requests using Tokio:
use std::error::Error;
#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
let resp = reqwest::get("https://httpbin.org/ip")
.await?
.text()
.await?;
println!("{:#?}", resp);
Ok(())
}
In Cargo.toml:
[dependencies]
reqwest = "0.11"
tokio = { version = "1", features = ["full"] }
Hyper
Reqwest is an easy to use wrapper around Hyper, which is a popular HTTP library for Rust. You can use it directly if you need more control over managing connections. A Hyper-based example is below and is largely inspired by an example in its documentation:
use hyper::{body::HttpBody as _, Client, Uri};
use std::error::Error;
#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
let client = Client::new();
let res = client
.get(Uri::from_static("http://httpbin.org/ip"))
.await?;
println!("status: {}", res.status());
let buf = hyper::body::to_bytes(res).await?;
println!("body: {:?}", buf);
}
In Cargo.toml:
[dependencies]
hyper = { version = "0.14", features = ["full"] }
tokio = { version = "1", features = ["full"] }
Original answer (Rust 0.6)
I believe what you're looking for is in the standard library. now in rust-http and Chris Morgan's answer is the standard way in current Rust for the foreseeable future. I'm not sure how far I can take you (and hope I'm not taking you the wrong direction!), but you'll want something like:
// Rust 0.6 -- old code
extern mod std;
use std::net_ip;
use std::uv;
fn main() {
let iotask = uv::global_loop::get();
let result = net_ip::get_addr("www.duckduckgo.com", &iotask);
io::println(fmt!("%?", result));
}
As for encoding, there are some examples in the unit tests in src/libstd/net_url.rs.
Update: This answer refers to fairly ancient history. For the current best practices, please look at Isaac Aggrey's answer instead.
I've been working on rust-http, which has become the de facto HTTP library for Rust (Servo uses it); it's far from complete and very poorly documented at present. Here's an example of making a request and doing something with the status code:
extern mod http;
use http::client::RequestWriter;
use http::method::Get;
use http::status;
use std::os;
fn main() {
let request = RequestWriter::new(Get, FromStr::from_str(os::args()[1]).unwrap());
let response = match request.read_response() {
Ok(response) => response,
Err(_request) => unreachable!(), // Uncaught condition will have failed first
};
if response.status == status::Ok {
println!("Oh goodie, I got me a 200 OK response!");
} else {
println!("That URL ain't returning 200 OK, it returned {} instead", response.status);
}
}
Run this code with a URL as the sole command-line argument and it'll check the status code! (HTTP only; no HTTPS.)
Compare with src/examples/client/client.rs for an example that does a little more.
rust-http is tracking the master branch of rust. At present it'll work in the just-released Rust 0.8, but there are likely to be breaking changes soon. Actually, no version of rust-http works on Rust 0.8—there was a breaking change which can't be worked around in privacy rules just before the release, leaving something that rust-http depends on in extra::url inaccessible. This has since been fixed, but it leaves rust-http incompatible with Rust 0.8.
As for the query string encoding matter, at present that should be done with extra::url::Query (a typedef for ~[(~str, ~str)]). Appropriate functions for conversions:
extra::url::query_to_str
extra::url::query_from_str (sorry, can't use this just at present as it's private. PR to make it public about to come. In the mean time, this link actually shouldn't work, it's only available because of https://github.com/mozilla/rust/issues/7476.)
Using curl bindings. Stick this in your Cargo.toml:
[dependencies.curl]
git = "https://github.com/carllerche/curl-rust"
...and this in the src/main.rs:
extern crate curl;
use curl::http;
fn main(){
let resp = http::handle()
.post("http://localhost:3000/login", "username=dude&password=sikrit")
.exec().unwrap();
println!("code={}; headers={}; body={}",
resp.get_code(), resp.get_headers(), resp.get_body());
}
I prefer Crates with low dependency count, so I would recommend these:
MinReq (0 deps)
use minreq;
fn main() -> Result<(), minreq::Error> {
let o = minreq::get("https://speedtest.lax.hivelocity.net").send()?;
let s = o.as_str()?;
print!("{}", s);
Ok(())
}
HTTP_Req (35 deps)
use {http_req::error, http_req::request, std::io, std::io::Write};
fn main() -> Result<(), error::Error> {
let mut a = Vec::new();
request::get("https://speedtest.lax.hivelocity.net", &mut a)?;
io::stdout().write(&a)?;
Ok(())
}
To elaborate on Isaac Aggrey's answer, here's an example of making a POST request with query parameters using the reqwest library.
Cargo.toml
[package]
name = "play_async"
version = "0.1.0"
edition = "2018"
[dependencies]
reqwest = "0.10.4"
tokio = { version = "0.2.21", features = ["macros"] }
Code
use reqwest::Client;
type Error = Box<dyn std::error::Error>;
type Result<T, E = Error> = std::result::Result<T, E>;
async fn post_greeting() -> Result<()> {
let client = Client::new();
let req = client
// or use .post, etc.
.get("https://webhook.site/1dff66fd-07ff-4cb5-9a77-681efe863747")
.header("Accepts", "application/json")
.query(&[("hello", "1"), ("world", "ABCD")]);
let res = req.send().await?;
println!("{}", res.status());
let body = res.bytes().await?;
let v = body.to_vec();
let s = String::from_utf8_lossy(&v);
println!("response: {} ", s);
Ok(())
}
#[tokio::main]
async fn main() -> Result<()> {
post_greeting().await?;
Ok(())
}
Go to https://webhook.site and create your webhook link and change the code to match. You'll see the request was received on server in realtime.
This example was originally based on Bastian Gruber's example and has been updated for modern Rust syntax and newer crate versions.
Building upon Patrik Stas' answer, if you want to do an HTTP form URL-encoded POST, here is what you have to do. In this case, it's to get an OAuth client_credentials token.
Cargo.toml
[dependencies]
reqwest = "0.10.4"
tokio = { version = "0.2.21", features = ["macros"] }
Code
use reqwest::{Client, Method};
type Error = Box<dyn std::error::Error>;
type Result<T, E = Error> = std::result::Result<T, E>;
async fn print_access_token() -> Result<()> {
let client = Client::new();
let host = "login.microsoftonline.com";
let tenant = "TENANT";
let client_id = "CLIENT_ID";
let client_secret = "CLIENT_SECRET";
let scope = "https://graph.microsoft.com/.default";
let grant_type = "client_credentials";
let url_string = format!("https://{}/{}/oauth2/v2.0/token", host, tenant);
let body = format!(
"client_id={}&client_secret={}&scope={}&grant_type={}",
client_id, client_secret, scope, grant_type,
);
let req = client.request(Method::POST, &url_string).body(body);
let res = req.send().await?;
println!("{}", res.status());
let body = res.bytes().await?;
let v = body.to_vec();
let s = String::from_utf8_lossy(&v);
println!("response: {} ", s);
Ok(())
}
#[tokio::main]
async fn main() -> Result<()> {
print_access_token().await?;
Ok(())
}
This will print something like the following.
200 OK
response: {"token_type":"Bearer","expires_in":3599,"ext_expires_in":3599,"access_token":"ACCESS_TOKEN"}
Dropping a version here that uses the surf crate (dual to the tide crate):
let res = surf::get("https://httpbin.org/get").await?;
assert_eq!(res.status(), 200);
Using hyper "0.13"
Also using hyper-tls for HTTPS support.
File Cargo.toml
hyper = "0.13"
hyper-tls = "0.4.1"
tokio = { version = "0.2", features = ["full"] }
Code
extern crate hyper;
use hyper::Client;
use hyper::body::HttpBody as _;
use tokio::io::{stdout, AsyncWriteExt as _};
use hyper_tls::HttpsConnector;
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
// HTTP only
// let client = Client::new();
// http or https connections
let client = Client::builder().build::<_, hyper::Body>(HttpsConnector::new());
let mut resp = client.get("https://catfact.ninja/fact".parse()?).await?;
println!("Response: {}", resp.status());
while let Some(chunk) = resp.body_mut().data().await {
stdout().write_all(&chunk?).await?;
}
Ok(())
}
Adapted from https://hyper.rs/guides/client/basic/
Simple http request with this crate: wsd
fn test() {
wsd::http::get("https://docs.rs/", |data| {
println!("status = {}, data = {}", data.status(), data.text());
});
}