Struct gotham::pipeline::Pipeline

source · [−]

pub struct Pipeline<T> where
    T: NewMiddlewareChain,  { /* private fields */ }

Expand description

When using middleware, one or more Middleware are combined to form a Pipeline. Middleware are invoked strictly in the order they’re added to the Pipeline.

At Request dispatch time, the Middleware are created from the NewMiddleware values given to the PipelineBuilder, and combined with a Handler created from the NewHandler provided to Pipeline::call. These Middleware and Handler values are used for a single Request.

Examples

#[derive(StateData)]
struct MiddlewareData {
    vec: Vec<i32>
}

#[derive(NewMiddleware, Copy, Clone)]
struct MiddlewareOne;

impl Middleware for MiddlewareOne {
    // Implementation elided.
    // Appends `1` to `MiddlewareData.vec`
}

#[derive(NewMiddleware, Copy, Clone)]
struct MiddlewareTwo;

impl Middleware for MiddlewareTwo {
    // Implementation elided.
    // Appends `2` to `MiddlewareData.vec`
}

#[derive(NewMiddleware, Copy, Clone)]
struct MiddlewareThree;

impl Middleware for MiddlewareThree {
    // Implementation elided.
    // Appends `3` to `MiddlewareData.vec`
}

fn handler(state: State) -> (State, Response<Body>) {
    let body = {
       let data = state.borrow::<MiddlewareData>();
       format!("{:?}", data.vec)
    };

    let res = create_response(&state,
                              StatusCode::OK,
                              mime::TEXT_PLAIN,
                              body);

    (state, res)
}

fn main() {
    let (chain, pipelines) = single_pipeline(
        new_pipeline()
            .add(MiddlewareOne)
            .add(MiddlewareTwo)
            .add(MiddlewareThree)
            .build()
    );

    let router = build_router(chain, pipelines, |route| {
        route.get("/").to(handler);
    });

    let test_server = TestServer::new(router).unwrap();
    let response = test_server.client().get("http://example.com/").perform().unwrap();
    assert_eq!(response.status(), StatusCode::OK);
    assert_eq!(response.read_utf8_body().unwrap(), "[1, 2, 3]");
}