Hey everyone, I started working with http4k recent...

# http4k

[Alberto Cabello]

Hey everyone, I started working with http4k recently, and I noticed there's no way to chain contracts together like you can with regular routes. With regular routes I could do something like

class A {
   fun getHandler(): RoutingHttpHandler {.....}
}

fun main() {
    val app = routes(
        "/A" bind A.getHandler()
}

In looking to replicate that with contracts, I found you can't really. Looking into making a contribution to the codebase, how would you guys want that to look? I can PR the repo fairly easily with my first thought which was a withRoutesFrom method that would look like

class A {
    fun getHandler(): ContractRoutingHandler {...}
}

fun main() {
    val app = contract {...}.withRoutesFrom("/A" bind A.getHandler(), "/B" bind B.getHandler()...
}

Is this something interesting, or is there another solution you guys have had in mind that would be preferred? Maybe I can tackle it

[dave]

The contract is just a routing http handler, and hence you can just compose them into any other routes block. The semantics are slightly different when it comes to filter handling - for that you should know how filters are applied in routing http handlers Vs standard http handlers (in the former they are applied after matching by default).

[dave]

But overall if you explain the route structure you want then we can probably help you to get there .

[Alberto Cabello]

My thought process is I'd have a bunch of classes that expose something, either a list of ContractRoutes, or ContractRoutingHttpHandler, and then in the final app composition, I could preface the exposed item with a name, similar to how I have it in the first example. The problem I noticed was if I expose a List<ContractRoutes>, I can't "/prefix" bind them. I'd have to manually write out something like

contract {
    routes.plusAssign(A.getRoutes())
    routes.plusAssing(B.getRoutes())
    ...
}

And in the routes themselves, I'd have to put the prefix every time. A minor grievance, but one that's not present in non-contract routing, and would be alleviated if I could somehow reference the actual routes from a contract.

If I expose a ContractRoutingHttpHandler I can't compose them without losing the OpenAPI spec since routes("prefix" bind ContractRoutingHttpHandler) strips the spec off, and I can't just do

contract {
    routes.plusAssign(("/prefix" bind someOtherContract).routes)
}

Since the route object is private

[dave]

Could you longer form that slightly into a gist? Even if it doesnt compile? 🙃

[Alberto Cabello]

No problem, sorry for my poor wording 🙂 https://gist.github.com/albertcabello/3f042d81ef6d10950db8e6e392fae681

[Alberto Cabello]

Googling around before I came up with this led me to [this thread](https://kotlinlang.slack.com/archives/C5AL3AKUY/p1555993080080100). Seems the solution then was to iterate over a list of routes and plusAssign them all, I was just hoping to get something nicer and more inline with how it is with non-contract routes

[dave]

It's not especially your wording - its that it's easier for people to play with when it's already code. 🙃 .

The contract stuff is a bit limited right now- it will be reworked at some point when we get the inspiration.

[Alberto Cabello]

It's not especially your wording - its that it's easier for people to play with when it's already code.

That's true!

when we get the inspiration

Totally get it, I figured I'd ask if the proposed withRoutesFrom was something you'd be interested in before I put in a PR for it