[−][src]Trait actix_service::Transform
The Transform
trait defines the interface of a service factory that wraps inner service
during construction.
Transform(middleware) wraps inner service and runs during inbound and/or outbound processing in the request/response lifecycle. It may modify request and/or response.
For example, timeout transform:
pub struct Timeout<S> { service: S, timeout: Duration, } impl<S> Service for Timeout<S> where S: Service, { type Request = S::Request; type Response = S::Response; type Error = TimeoutError<S::Error>; type Future = TimeoutServiceResponse<S>; fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> { ready!(self.service.poll_ready(cx)).map_err(TimeoutError::Service) } fn call(&mut self, req: S::Request) -> Self::Future { TimeoutServiceResponse { fut: self.service.call(req), sleep: Delay::new(clock::now() + self.timeout), } } }
Timeout service in above example is decoupled from underlying service implementation and could be applied to any service.
The Transform
trait defines the interface of a Service factory. Transform
is often implemented for middleware, defining how to construct a
middleware Service. A Service that is constructed by the factory takes
the Service that follows it during execution as a parameter, assuming
ownership of the next Service.
Factory for Timeout
middleware from the above example could look like this:
pub struct TimeoutTransform { timeout: Duration, } impl<S> Transform<S> for TimeoutTransform<E> where S: Service, { type Request = S::Request; type Response = S::Response; type Error = TimeoutError<S::Error>; type InitError = S::Error; type Transform = Timeout<S>; type Future = Ready<Result<Self::Transform, Self::InitError>>; fn new_transform(&self, service: S) -> Self::Future { ok(TimeoutService { service, timeout: self.timeout, }) } }
Associated Types
type Request
Requests handled by the service.
type Response
Responses given by the service.
type Error
Errors produced by the service.
type Transform: Service<Request = Self::Request, Response = Self::Response, Error = Self::Error>
The TransformService
value created by this factory
type InitError
Errors produced while building a transform service.
type Future: Future<Output = Result<Self::Transform, Self::InitError>>
The future response value.
Required methods
fn new_transform(&self, service: S) -> Self::Future
Creates and returns a new Transform component, asynchronously
Provided methods
fn map_init_err<F, E>(self, f: F) -> TransformMapInitErr<Self, S, F, E> where
Self: Sized,
F: Fn(Self::InitError) -> E + Clone,
Self: Sized,
F: Fn(Self::InitError) -> E + Clone,
Map this transforms's factory error to a different error, returning a new transform service factory.
Implementations on Foreign Types
impl<T, S> Transform<S> for Rc<T> where
T: Transform<S>,
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T: Transform<S>,
type Request = T::Request
type Response = T::Response
type Error = T::Error
type InitError = T::InitError
type Transform = T::Transform
type Future = T::Future
fn new_transform(&self, service: S) -> T::Future
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impl<T, S> Transform<S> for Arc<T> where
T: Transform<S>,
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T: Transform<S>,
type Request = T::Request
type Response = T::Response
type Error = T::Error
type InitError = T::InitError
type Transform = T::Transform
type Future = T::Future
fn new_transform(&self, service: S) -> T::Future
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Implementors
impl<T, S, F, E> Transform<S> for TransformMapInitErr<T, S, F, E> where
T: Transform<S>,
F: Fn(T::InitError) -> E + Clone,
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T: Transform<S>,
F: Fn(T::InitError) -> E + Clone,