Anyone experienced with http4k? I'm trying to add ...

# http4k

[roby]

Anyone experienced with http4k? I'm trying to add routes with documentation but for somereason the routes are not getting registered?

kt
    val contract = contract {
        renderer = OpenApi3(ApiInfo("Tasks API", "v0.1.0"), Argo)
        descriptionPath = "/docs"

        routes += UserRouter(userService).routes // these dont work
        routes += "/ping" bindContract Method.GET to { _ -> Response(Status.OK).body("pong") } // this works
    }

    val handler = routes("/api" bind contract)
    handler.asServer(Jetty(port)).start() ..

//....

class UserRouter(private val services: UserService) {

    val routes: List<ContractRoute> = listOf(
                "/users/{id}" meta {
            summary = "Get user details"
            returning(
                Status.BAD_REQUEST to "Invalid id",
                Status.NOT_FOUND to "User not found"
            )
        } bindContract GET to ::getUser,

[Andrew O'Hara]

Defining a ContractRoute with a path parameter would typically look like

"/users" / idLens meta {
  ...
} bindContract GET to { id ->
  { req ->
    ...
  }
}

I'm not entirely sure if the contract router is unable to route for non-contract path parameters, but fixing that would be the first thing to try.

[Andrew O'Hara]

You can also try adding another route inside the contract that doesn't have a path parameter, as a quick sanity check

[roby]

ok i was able to do it like this:

"/users" / <http://Path.int|Path.int>().of("id") meta {
            summary = "Get user details"
            returning(
                Status.BAD_REQUEST to "Invalid id",
                Status.NOT_FOUND to "User not found"
            )
        } bindContract GET to { id ->
            {
                getUser(id)
            }
        },

// ...

    private fun getUser(userId: Int): Response = errorHandler {
        val res = services.getUser(userId)

        Response(Status.OK)
            .header("content-type", "application/json")
            .body(Json.encodeToString(res))
    }

[roby]

Isnt there any possible way to still make the lambda receive request parameter?

[roby]

or do i have to getUser(id, it)

[roby]

"/users" / <http://Path.int|Path.int>().of("id") meta {
            summary = "Get user details"
            returning(
                Status.BAD_REQUEST to "Invalid id",
                Status.NOT_FOUND to "User not found"
            )
        } bindContract GET to { id -> { req ->
                getUser(req, id)
            }
        },

idk, this looks a bit awful

[Andrew O'Hara]

Does this give you what you need?

bindContract GET to { id ->
  { req ->
    getUser(id)
  }
}

[roby]

yes, it just looks weird, another problem i am having is for example defining this route:
users/{id}/boards

[roby]

image.png

[roby]

adding / "boards" after the path... id thing is throwing error at the whole code

[roby]

val test = "/users" / <http://Path.int|Path.int>().of("id") / "boards" meta {
        summary = "Get the list with all user available boards"
        returning(
            Status.OK to "User boards",
            Status.BAD_REQUEST to "Invalid id",
            Status.NOT_FOUND to "User not found"
        )
    } bindContract GET to ::getUserBoards

[roby]

this is getting casted to

Pair<ContractRouteSpec2<Int, String>.Binder, KFunction1<Request, Response>>

(?)

[roby]

instead of ContractRoute

[Andrew O'Hara]

If you see little benefit in having your path parameters provided by the contract handler in a typesafe manner, then you can omit the extra layer by adding an explicit Request type parameter to req

"/foo" / idLens meta {
  ...
} bindContract GET to { req: Request ->
  Response(OK)
}

The issue with the new route you've added is that you're not handling the value of the new boards parameter (even though it's not a lens).

val test = "/users" / <http://Path.int|Path.int>().of("id") / "boards" meta {
  ...
} bindContract GET to { id, _ ->
  { req ->
    Response(OK)
  }
}

Notice the _ parameter added after id. Since we don't care about its value, it can be named _ and ignored

[Andrew O'Hara]

You may also want to share the id PathLens between routes, rather than redefine it each time you add a new route.

[roby]

What does "Lens" mean in this case?

[Andrew O'Hara]

val idLens: BiDiPathLens<Int> = <http://Path.int|Path.int>().of("id")

A lens is a typesafe way to get data in and out of an http message (ie request or response). So to share it, you would so something like:

val getUser = "/users" / idLens bindContract GET
val putUser = "/users" / idLens bindContract PUT

The benefit is that you can reuse the lens in other contracts or in a client call

val response = getUser
  .newRequest(hostname)
  .with(idLens of 123)
  .let(httpHandler)

[Andrew O'Hara]

https://www.http4k.org/guide/howto/typesafe_your_api_with_lenses/