https://github.com/polyvariant/smithy4s-caliban

Smithy4s integration for Caliban, a Scala GraphQL library.
https://github.com/polyvariant/smithy4s-caliban

caliban graphql graphql-server scala smithy smithy4s

Last synced: 27 days ago
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Smithy4s integration for Caliban, a Scala GraphQL library.

• Host: GitHub
• URL: https://github.com/polyvariant/smithy4s-caliban
• Owner: polyvariant
• License: other
• Created: 2023-05-30T22:22:49.000Z (over 1 year ago)
• Default Branch: main
• Last Pushed: 2023-10-22T16:40:31.000Z (about 1 year ago)
• Last Synced: 2024-09-29T12:03:41.735Z (about 1 month ago)
• Topics: caliban, graphql, graphql-server, scala, smithy, smithy4s
• Language: Scala
• Homepage:
• Size: 75.2 KB
• Stars: 15
• Watchers: 5
• Forks: 0
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.md

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README

        
# smithy4s-caliban

[Smithy4s](https://disneystreaming.github.io/smithy4s/) integration for [Caliban](https://ghostdogpr.github.io/caliban/).

## Installation

In sbt:

```scala

libraryDependencies ++= Seq("org.polyvariant" %% "smithy4s-caliban" % version)

```

In scala-cli:

```

//> using lib "org.polyvariant::smithy4s-caliban:version"

```

## Usage

### Set up smithy4s

Follow the [quickstart steps](https://disneystreaming.github.io/smithy4s/docs/overview/quickstart).

### Write a Smithy spec

For example:

```smithy

$version: "2"

namespace hello

service HelloService {

    operations: [GetHello]

}

@readonly

operation GetHello {

    input := {

        @required

        name: String

    }

    output := {

        @required

        greeting: String

    }

}

```

Make sure you can generate Smithy4s code for that spec.

### Implement service

Implement the trait generated by Smithy4s:

```scala mdoc

import hello._

import cats.effect._

val impl: HelloService[IO] = new HelloService[IO] {

  override def getHello(name: String): IO[GetHelloOutput] =

    IO.println("hello, " + name).as(GetHelloOutput("hello, " + name))

}

```

### Interpret to GraphQL

This is what the library will allow you to do: convert that service implementation to a GraphQL root.

```scala mdoc

import org.polyvariant.smithy4scaliban._

import caliban.GraphQL

val api: Resource[IO, GraphQL[Any]] = CalibanGraphQLInterpreter.server(impl)

```

This returns a Resource because it requires (and creates) a `Dispatcher`.

Now, the last part - you have to connect this GraphQL instance to a server. How you do it is up to you, but [http4s](https://ghostdogpr.github.io/caliban/docs/adapters.html#json-handling) is recommended. Here's a full example (requires `caliban-http4s`, `tapir-json-circe` and `http4s-ember-server`):

```scala mdoc

import caliban.Http4sAdapter

import caliban.CalibanError

import caliban.interop.tapir.HttpInterpreter

import sttp.tapir.json.circe._

import caliban.interop.cats.implicits._

import org.http4s.ember.server.EmberServerBuilder

val server: IO[Nothing] = api.evalMap { serverApi =>

  implicit val rt: zio.Runtime[Any] = zio.Runtime.default

  serverApi

    .interpreterAsync[IO]

    .map { interp =>

      Http4sAdapter.makeHttpServiceF[IO, Any, CalibanError](HttpInterpreter(interp))

    }

}

.flatMap { routes =>

  EmberServerBuilder.default[IO].withHttpApp(routes.orNotFound).build

}.useForever

```

This will launch a server on `localhost:8080` running your Smithy spec as a GraphQL API.