Add experimantal singleRouteNextJsHandler

src/Fastify.res

@@ -194,7 +194,8 @@ let route = (app: t, restRoute: Rest.route<'request, 'response>, fn) => {
   // 1. To be able to configure ContentTypeParser specifically for the route
   // 2. To get access to app with registered plugins eg Swagger
   app->internalRegister((app, _, done) => {
-    let {definition, variablesSchema, responses, pathItems, isRawBody} = restRoute->Rest.params
+    let {definition, variablesSchema, responseSchema, responses, pathItems, isRawBody} =
+      restRoute->Rest.params
 
     let url = ref("")
     for idx in 0 to pathItems->Js.Array2.length - 1 {
@@ -205,10 +206,8 @@ let route = (app: t, restRoute: Rest.route<'request, 'response>, fn) => {
       }
     }
 
-    let responseSchemas = []
     let routeSchemaResponses: dict<routeResponse> = Js.Dict.empty()
     responses->Js.Array2.forEach(r => {
-      responseSchemas->Js.Array2.push(r.schema)->ignore
       let status = switch r.status {
       | Some(status) => status->(Obj.magic: int => string)
       | None => "default"
@@ -235,8 +234,6 @@ let route = (app: t, restRoute: Rest.route<'request, 'response>, fn) => {
       )
     })
 
-    let responseSchema = S.union(responseSchemas)
-
     let routeSchema = {
       description: ?definition.description,
       summary: ?definition.summary,
@@ -261,8 +258,8 @@ let route = (app: t, restRoute: Rest.route<'request, 'response>, fn) => {
             raise(%raw(`0`))
           }
         }
-        fn(variables)->Promise.thenResolve(handlerReturn => {
-          let data: {..} = handlerReturn->S.reverseConvertOrThrow(responseSchema)->Obj.magic
+        fn(variables)->Promise.thenResolve(implementationResult => {
+          let data: {..} = implementationResult->S.reverseConvertOrThrow(responseSchema)->Obj.magic
           let headers = data["headers"]
           if headers->Obj.magic {
             reply.headers(headers)

src/Rest.res

@@ -251,6 +251,7 @@ type routeParams<'variables, 'response> = {
   definition: definition<'variables, 'response>,
   pathItems: array<pathItem>,
   variablesSchema: S.t<'variables>,
+  responseSchema: S.t<'response>,
   responses: array<Response.t<'response>>,
   responsesMap: dict<Response.t<'response>>,
   isRawBody: bool,
@@ -526,6 +527,7 @@ let params = route => {
       let params = {
         definition: routeDefinition,
         variablesSchema,
+        responseSchema: S.union(responses->Js.Array2.map(r => r.schema)),
         responses,
         pathItems,
         responsesMap,
@@ -720,3 +722,57 @@ let client = (~baseUrl, ~fetcher=ApiFetcher.default, ~jsonQuery=false) => {
     jsonQuery,
   }
 }
+
+type nextJsHandler
+
+let singleRouteNextJsHandler = (route, implementation): nextJsHandler => {
+  let {pathItems, definition, isRawBody, responseSchema, variablesSchema} = route->params
+
+  // TOD: Validate that we match the req path
+  pathItems->Js.Array2.forEach(pathItem => {
+    switch pathItem {
+    | Param(param) =>
+      panic(
+        `Route ${definition.path} contains a path param ${param.name} which is not supported by Next.js handler yet`,
+      )
+    | Static(_) => ()
+    }
+  })
+  if isRawBody {
+    panic(
+      `Route ${definition.path} contains a raw body which is not supported by Next.js handler yet`,
+    )
+  }
+
+  (
+    async (req, res) => {
+      if req["method"] !== definition.method {
+        res["status"](404)["end"]()
+      }
+      switch req->S.parseOrThrow(variablesSchema) {
+      | variables =>
+        try {
+          let implementationResult = await implementation(variables)
+          let data: {..} = implementationResult->S.reverseConvertOrThrow(responseSchema)->Obj.magic
+          let headers: option<dict<string>> = data["headers"]
+          switch headers {
+          | Some(headers) =>
+            headers
+            ->Js.Dict.keys
+            ->Js.Array2.forEach(key => {
+              res["setHeader"](key, headers->Js.Dict.unsafeGet(key))
+            })
+          | None => ()
+          }
+          res["status"](%raw(`data.status || 200`))
+        } catch {
+        | S.Raised(error) =>
+          Js.Exn.raiseError(
+            `Unexpected error in the ${definition.path} route: ${error->S.Error.message}`,
+          )
+        }
+      | exception S.Raised(error) => res["status"](400)["send"](error->S.Error.message)
+      }
+    }
+  )->Obj.magic
+}

src/Rest.resi

@@ -149,6 +149,7 @@ type routeParams<'variables, 'response> = {
   definition: definition<'variables, 'response>,
   pathItems: array<pathItem>,
   variablesSchema: S.t<'variables>,
+  responseSchema: S.t<'response>,
   responses: array<Response.t<'response>>,
   responsesMap: dict<Response.t<'response>>,
   isRawBody: bool,
@@ -175,3 +176,9 @@ let fetch: (
   ~fetcher: ApiFetcher.t=?,
   ~jsonQuery: bool=?,
 ) => promise<'response>
+
+type nextJsHandler
+let singleRouteNextJsHandler: (
+  route<'variables, 'response>,
+  'variables => promise<'response>,
+) => nextJsHandler