Cannot specify a dynamic URL for http queries.

In the simple example, one can specify the following: state.asyn().http().get("https://bevyengine.org")

but not

state.asyn().http().get(url) if url is defined in the outer scope or if it depends on anything in the outer scope.

The error is:

examples/simple.rs:25:15
   |
25 |           .then(asyn!(state => {
   |  _______________^
26 | |             info!("How large is is the Bevy main web page?");
27 | |             state.asyn().http().get(url)
28 | |         }))
   | |__________^ expected fn pointer, found closure
   |
   = note: expected fn pointer `for<'a, 'b> fn(In<(PromiseState<f32>, ())>, StaticSystemParam<'a, 'b, ()>) -> StatefulRequest<f32>

If you wanted to do a REST query where you have to specify some dynamic parameters, this would not compile. Is there any workaround?

Oh. Sorry, missed this one.

You can

use send() method on request that return promise
create higher lever methods for invoking rest api

This is how you can bypass arguments from your systems to url with send():

fn make_rest_call(mut commands: Commands) {
    // you can get query args from events, resources, whatever you want
    let q = "jkbo";
    let url = format!("https://api.github.com/search/users?q={q}");
    commands.add(asyn::http::get(url).send().then(asyn!(|_, r| {
        match r {
            Ok(r) => info!("{0}", r.text().unwrap()),
            Err(e) => error!("{e}")
        }
    })));
}

There is how it is possible to create higher level methods for calling rest api:

use bevy::prelude::*;
use pecs::prelude::*;
use serde::Deserialize;
use serde_json;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_plugins(PecsPlugin)
        .add_systems(Startup, make_rest_call)
        .run();
}

#[derive(Deserialize)]
struct FoundUsers {
    items: Vec<User>,
}

#[derive(Deserialize)]
struct User {
    id: usize,
    login: String,
}

// make search users request to GitHub, return promise resolved 
// with found Users
fn find_github_users(q: &'static str) -> Promise<(), Result<Vec<User>, String>> {
    let url = format!("https://api.github.com/search/users?q={q}");
    asyn::http::get(url).send().then(asyn!(_, result => {
        Promise::resolve(result.and_then(|resp| {
            let text = resp.text().unwrap();
            if !resp.ok {
                Err(format!("[{} {}] {text}", resp.status, resp.status_text))
            } else {
                serde_json::from_str::<FoundUsers>(text)
                    .map_err(|e| e.to_string())
                    .map(|found| found.items)
            }
        }))
    }))
}

fn make_rest_call(mut commands: Commands) {
    commands.add(find_github_users("jkbo").then(asyn!(_, resp => {
        match resp {
            Err(e) => error!("{e}"),
            Ok(items) => for user in items.iter() {
                info!("{} # {}", user.id, user.login)
            }
        }
        asyn::app::exit()
    })));
}

jkb0o / pecs

Cannot specify a dynamic URL for http queries. #6