Custom Handling of HEAD, OPTIONS, and TRACE Methods

Implementing HTTP methods such as HEAD, OPTIONS, and TRACE with the Volga can be streamlined using well-defined steps. This guide presents effective ways to handle these methods in your Volga application.

HEAD Method

By default, when you map a handler to the GET method, Volga also maps it to the HEAD method. The HEAD method will return the headers without the body.

To customize the behavior for the HEAD method, explicitly define it using the map_head method:

use volga::{App, ok};

#[tokio::main]
async fn main() -> std::io::Result<()> {
    let mut app = App::new();

    // HEAD /resource
    app.map_head("/resource", || async {
        ok!([
            ("x-custom-header", "some-value-get")
        ])
    });

    // GET /resource
    app.map_get("/resource", || async {
        ok!("Hello World!", [
            ("x-custom-header", "some-value-get")
        ])
    });

    app.run().await
}

Here, the HEAD method returns headers without a body, often mirroring the headers that a GET request would have returned.

OPTIONS Method

For specifically handling OPTIONS requests, use the map_options method to map this HTTP method:

use volga::{App, ok};

#[tokio::main]
async fn main() -> std::io::Result<()> {
    let mut app = App::new();

    // OPTIONS /resource
    app.map_options("/resource", || async {
        ok!([
            ("Allow", "GET, OPTIONS")
        ])
    });

    // GET /resource
    app.map_get("/resource", || async {
        ok!("Hello World!")
    });

    app.run().await
}

The example above includes the Allow header to indicate supported HTTP methods for the resource. The response body is optional, based on the specific needs of your API.

TRACE Method

The TRACE method is useful for debugging, as it enables tracing the request path to the server and returns the request message for diagnostic purposes:

use volga::{App, HttpRequest, stream};

#[tokio::main]
async fn main() -> std::io::Result<()> {
    let mut app = App::new();

    // TRACE /
    app.map_trace("/", |req: HttpRequest| async move {
        let boxed_body = req.into_boxed_body();
        stream!(boxed_body, [
            ("content-type", "message/http")
        ])
    });

    app.run().await
}

This handler captures the incoming request and sends it back in the response with the appropriate content type.

You can check th examples here:

• HEAD
• OPTIONS
• TRACE