[Question] How to use actions in `ros2_rust`?

[drewlwhitney]

Hey there!

I'm trying to write an action server in Rust, but it looks like some of the documentation is still in-progress. Could someone help me understand how we do this in Rust? This is what I have so far:

use motor_control_interfaces::action::TestAction;
use rclrs::*;
use std::time::Duration;


fn main() {
    // set up ROS
    let mut executor = Context::default_from_env()
        .expect("Failed to create ROS context")
        .create_basic_executor();
    let node = executor.create_node("test_node").expect("Failed to create node");

    // create action
    let _action = node
        .create_action_server("test_action", async |request: RequestedGoal<TestAction>| {
            let task = request.accept().execute();
            let number_of_prints = task.goal().number_of_prints;
            let terminated_goal = if let Err(_) = task.unless_cancel_requested((async || {
                // print and publish feedback
                for _ in 0..number_of_prints {
                    println!("Running!");
                    task.publish_feedback(?????);
                    tokio::time::sleep(Duration::from_secs(1));
                }
            })()).await {
                // I'm assuming that getting an `Err` means the task was cancelled. Is this correct?
                task.begin_cancelling().cancelled_with(?????)
            } else {
                // I'm assuming that if we got an `Ok`, we were not cancelled. Is that correct?
                task.succeeded_with(?????)
            };

            terminated_goal
        })
        .unwrap();

    println!("Running `test_node`...");

    executor.spin(SpinOptions::default()).first_error().unwrap();
}

Note that I have two closures: one for create_action_server() and one for unless_cancel_requested() (the second one is called immediately to create a future). How do I publish feedback, accept a cancellation, and publish the result? Basically, what do I need to replace the ?????s with in my example? I saw that the TestAction_Result and TestAction_Feedback structs were generated in addition to the TestAction struct. Do I need to construct these manually, or is there another method to create them?

Thanks!