9ccb5afa9f
This commit introduces a new type-level combinator, `WithRoutingHeader`.
It modifies the behaviour of the following sub-API, such that all endpoint
of said API return an additional routing header in their response.
A routing header is a header that specifies which endpoint the
incoming request was routed to.
Endpoint are designated by their path, in which `Capture'` and
`CaptureAll` combinators are replaced by a capture hint.
This header can be used by downstream middlewares to gather
information about individual endpoints, since in most cases
a routing header uniquely identifies a single endpoint.
Example:
```haskell
type MyApi =
WithRoutingHeader :> "by-id" :> Capture "id" Int :> Get '[JSON] Foo
-- GET /by-id/1234 will return a response with the following header:
-- ("Servant-Routed-Path", "/by-id/<id::Int>")
```
To achieve this, two refactorings were necessary:
* Introduce a type `RouterEnv env` to encapsulate the `env` type
(as in `Router env a`), which contains a tuple-encoded list of url
pieces parsed from the incoming request.
This type makes it possible to pass more information throughout the
routing process, and the computation of the `Delayed env c` associated
with each request.
* Introduce a new kind of router, which only modifies the RouterEnv, and
doesn't affect the routing process otherwise.
`EnvRouter (RouterEnv env -> RouterEnv env) (Router' env a)`
This new router is used when encountering the `WithRoutingHeader`
combinator in an API, to notify the endpoints of the sub-API that they
must produce a routing header (this behaviour is disabled by default).
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| example | ||
| src | ||
| test | ||
| CHANGELOG.md | ||
| LICENSE | ||
| README.md | ||
| servant-server.cabal | ||
| Setup.hs | ||
servant-server
This library lets you implement an HTTP server with handlers for each endpoint of a servant API, handling most of the boilerplate for you.
Getting started
We've written a tutorial guide that introduces the core types and features of servant. After this article, you should be able to write your first servant webservices, learning the rest from the haddocks' examples.