Attribute Macro mendes_macros::handler

source ·

#[handler]

Expand description

Implement a request handler wrapper for the annotated function

The attribute takes allowed methods as its arguments:

/// This handler will immediately return a `405 Method not allowed`
/// error for all request methods other than `GET`
#[handler(GET)]
fn hello(_: &App) -> Result<Response<String>, Error> {
    Ok(Response::builder()
        .status(StatusCode::OK)
        .body("Hello, world".into())
        .unwrap())
}

The first argument of the function must be a reference to an implementer of the Application trait (the implementor may also be wrapped in an Arc). All unannotated arguments must be of types that implement the FromContext trait for the Application type used in the first argument. This includes &http::request::Parts, the Request’s headers and any number of types that can represent a path component from the URI:

&[u8] for the bytes representation of the path component
Cow<'_, str>
String
Numeric types (i8, u8, i16, u16, …, isize, usize, f32, f64)
bool and char
If the hyper feature is enabled, hyper::body::Body (only if Application::RequestBody is also Body)

Each of these types can be wrapped in Option for optional path components. Additionally, there are two attributes that may be used on handler arguments:

#[rest]: a &str representing the part of the request path not yet consumed by routing
#[query]: a type that implements Deserialize, and will be used to deserialize the URI query

This macro will generate a module that contains a call() function mirroring the original function, and you may rely on this behavior (for example, for testing).

mod hello {
   use super::*;
   /// ... some internals hidden ...
   pub(super) async fn call(_: &App) -> Result<Response<Body>, Error> {
       Ok(Response::builder()
           .status(StatusCode::OK)
           .body("Hello, world".into())
           .unwrap())
   }
}