[−][src]Trait warp::Filter
Composable request filters.
A Filter
can optionally extract some data from a request, combine
it with others, mutate it, and return back some value as a reply. The
power of Filter
s come from being able to isolate small subsets, and then
chain and reuse them in various parts of your app.
Extracting Tuples
You may notice that several of these filters extract some tuple, often times a tuple of just 1 item! Why?
If a filter extracts a (String,)
, that simply means that it
extracts a String
. If you were to map
the filter, the argument type
would be exactly that, just a String
.
What is it? It's just some type magic that allows for automatic combining
and flattening of tuples. Without it, combining two filters together with
and
, where one extracted ()
, and another String
, would mean the
map
would be given a single argument of ((), String,)
, which is just
no fun.
Provided methods
fn and<F>(self, other: F) -> And<Self, F> where
Self: Sized,
<Self::Extract as Tuple>::HList: Combine<<F::Extract as Tuple>::HList>,
F: Filter + Clone,
F::Error: CombineRejection<Self::Error>,
Self: Sized,
<Self::Extract as Tuple>::HList: Combine<<F::Extract as Tuple>::HList>,
F: Filter + Clone,
F::Error: CombineRejection<Self::Error>,
Composes a new Filter
that requires both this and the other to filter a request.
Additionally, this will join together the extracted values of both
filters, so that map
and and_then
receive them as separate arguments.
If a Filter
extracts nothing (so, ()
), combining with any other
filter will simply discard the ()
. If a Filter
extracts one or
more items, combining will mean it extracts the values of itself
combined with the other.
Example
use warp::Filter; // Match `/hello/:name`... warp::path("hello") .and(warp::path::param::<String>());
fn or<F>(self, other: F) -> Or<Self, F> where
Self: Filter<Error = Rejection> + Sized,
F: Filter,
F::Error: CombineRejection<Self::Error>,
Self: Filter<Error = Rejection> + Sized,
F: Filter,
F::Error: CombineRejection<Self::Error>,
Composes a new Filter
of either this or the other filter.
Example
use std::net::SocketAddr; use warp::Filter; // Match either `/:u32` or `/:socketaddr` warp::path::param::<u32>() .or(warp::path::param::<SocketAddr>());
fn map<F>(self, fun: F) -> Map<Self, F> where
Self: Sized,
F: Func<Self::Extract> + Clone,
Self: Sized,
F: Func<Self::Extract> + Clone,
Composes this Filter
with a function receiving the extracted value.
Example
use warp::Filter; // Map `/:id` warp::path::param().map(|id: u64| { format!("Hello #{}", id) });
Func
The generic Func
trait is implemented for any function that receives
the same arguments as this Filter
extracts. In practice, this
shouldn't ever bother you, and simply makes things feel more natural.
For example, if three Filter
s were combined together, suppose one
extracts nothing (so ()
), and the other two extract two integers,
a function that accepts exactly two integer arguments is allowed.
Specifically, any Fn(u32, u32)
.
Without Product
and Func
, this would be a lot messier. First of
all, the ()
s couldn't be discarded, and the tuples would be nested.
So, instead, you'd need to pass an Fn(((), (u32, u32)))
. That's just
a single argument. Bleck!
Even worse, the tuples would shuffle the types around depending on
the exact invocation of and
s. So, unit.and(int).and(int)
would
result in a different extracted type from unit.and(int.and(int)
,
or from int.and(unit).and(int)
. If you changed around the order
of filters, while still having them be semantically equivalent, you'd
need to update all your map
s as well.
Product
, HList
, and Func
do all the heavy work so that none of
this is a bother to you. What's more, the types are enforced at
compile-time, and tuple flattening is optimized away to nothing by
LLVM.
fn and_then<F>(self, fun: F) -> AndThen<Self, F> where
Self: Sized,
F: Func<Self::Extract> + Clone,
F::Output: TryFuture + Send,
<F::Output as TryFuture>::Error: CombineRejection<Self::Error>,
Self: Sized,
F: Func<Self::Extract> + Clone,
F::Output: TryFuture + Send,
<F::Output as TryFuture>::Error: CombineRejection<Self::Error>,
Composes this Filter
with a function receiving the extracted value.
The function should return some TryFuture
type.
The Error
type of the return Future
needs be a Rejection
, which
means most futures will need to have their error mapped into one.
Example
use warp::Filter; // Validate after `/:id` warp::path::param().and_then(|id: u64| async move { if id != 0 { Ok(format!("Hello #{}", id)) } else { Err(warp::reject::not_found()) } });
fn or_else<F>(self, fun: F) -> OrElse<Self, F> where
Self: Filter<Error = Rejection> + Sized,
F: Func<Rejection>,
F::Output: TryFuture<Ok = Self::Extract> + Send,
<F::Output as TryFuture>::Error: IsReject,
Self: Filter<Error = Rejection> + Sized,
F: Func<Rejection>,
F::Output: TryFuture<Ok = Self::Extract> + Send,
<F::Output as TryFuture>::Error: IsReject,
Compose this Filter
with a function receiving an error.
The function should return some TryFuture
type yielding the
same item and error types.
fn recover<F>(self, fun: F) -> Recover<Self, F> where
Self: Filter<Error = Rejection> + Sized,
F: Func<Rejection>,
F::Output: TryFuture + Send,
<F::Output as TryFuture>::Error: IsReject,
Self: Filter<Error = Rejection> + Sized,
F: Func<Rejection>,
F::Output: TryFuture + Send,
<F::Output as TryFuture>::Error: IsReject,
Compose this Filter
with a function receiving an error and
returning a new type, instead of the same type.
This is useful for "customizing" rejections into new response types. See also the rejections example.
fn unify<T>(self) -> Unify<Self> where
Self: Filter<Extract = (Either<T, T>,)> + Sized,
T: Tuple,
Self: Filter<Extract = (Either<T, T>,)> + Sized,
T: Tuple,
Unifies the extracted value of Filter
s composed with or
.
When a Filter
extracts some Either<T, T>
, where both sides
are the same type, this combinator can be used to grab the
inner value, regardless of which side of Either
it was. This
is useful for values that could be extracted from multiple parts
of a request, and the exact place isn't important.
Example
use std::net::SocketAddr; use warp::Filter; let client_ip = warp::header("x-real-ip") .or(warp::header("x-forwarded-for")) .unify() .map(|ip: SocketAddr| { // Get the IP from either header, // and unify into the inner type. });
fn untuple_one<T>(self) -> UntupleOne<Self> where
Self: Filter<Extract = (T,)> + Sized,
T: Tuple,
Self: Filter<Extract = (T,)> + Sized,
T: Tuple,
Convenience method to remove one layer of tupling.
This is useful for when things like map
don't return a new value,
but just ()
, since warp will wrap it up into a ((),)
.
Example
use warp::Filter; let route = warp::path::param() .map(|num: u64| { println!("just logging: {}", num); // returning "nothing" }) .untuple_one() .map(|| { println!("the ((),) was removed"); warp::reply() });
use warp::Filter; let route = warp::any() .map(|| { // wanting to return a tuple (true, 33) }) .untuple_one() .map(|is_enabled: bool, count: i32| { println!("untupled: ({}, {})", is_enabled, count); });
fn with<W>(self, wrapper: W) -> W::Wrapped where
Self: Sized,
W: Wrap<Self>,
Self: Sized,
W: Wrap<Self>,
Wraps the current filter with some wrapper.
The wrapper may do some preparation work before starting this filter, and may do post-processing after the filter completes.
Example
use warp::Filter; let route = warp::any() .map(warp::reply); // Wrap the route with a log wrapper. let route = route.with(warp::log("example"));
fn boxed(self) -> BoxedFilter<Self::Extract> where
Self: Sized + Send + Sync + 'static,
Self::Extract: Send,
Self::Error: Into<Rejection>,
Self: Sized + Send + Sync + 'static,
Self::Extract: Send,
Self::Error: Into<Rejection>,
Boxes this filter into a trait object, making it easier to name the type.
Example
use warp::Filter; fn impl_reply() -> warp::filters::BoxedFilter<(impl warp::Reply,)> { warp::any() .map(warp::reply) .boxed() } fn named_i32() -> warp::filters::BoxedFilter<(i32,)> { warp::path::param::<i32>() .boxed() } fn named_and() -> warp::filters::BoxedFilter<(i32, String)> { warp::path::param::<i32>() .and(warp::header::<String>("host")) .boxed() }