Initial support for JSON request/response

3 files changed, 48 insertions, 10 deletions

diff --git a/README.md b/README.md
index 133c826..183e89f 100644
--- a/README.md
+++ b/README.md
@@ -15,7 +15,7 @@ See the `example` directory for an example.
 - [x] server generation from protobuf Service definition
 - [x] client generation from protobuf Service definition
 - [x] protobuf input/output
-- [ ] json input/output
+- [x] json input/output
 - [x] asynchronous server
 - [x] synchronous client
 - [x] can serve multiple services easily (see [examples/multiservice](examples/multiservice))
diff --git a/nimtwirp/generator.nim b/nimtwirp/generator.nim
index e3f94b2..1ad9b96 100644
--- a/nimtwirp/generator.nim
+++ b/nimtwirp/generator.nim
@@ -54,7 +54,7 @@ proc new{service.name}*(): {service.name} =
     new(result)
 
 proc handleRequest*(service: {service.name}, req: Request): Future[nimtwirp.Response] {{.async.}} =
-    let (_, methodName) = validateRequest(req, {service.name}Prefix)
+    let (contentType, methodName) = validateRequest(req, {service.name}Prefix)
 
 """
 
@@ -64,9 +64,20 @@ proc handleRequest*(service: {service.name}, req: Request): Future[nimtwirp.Resp
             ifel = "elif"
         result &= &"""
     {ifel} methodName == "{meth.name}":
-        let inputMsg = new{meth.inputType}(req.body)
+        var inputMsg: {meth.inputType}
+
+        if contentType == "application/protobuf":
+            inputMsg = new{meth.inputType}(req.body)
+        elif contentType == "application/json":
+            let node = parseJson(req.body)
+            inputMsg = parse{meth.inputType}(node)
+
         let outputMsg = await {meth.name}(service, inputMsg)
-        return nimtwirp.newResponse(serialize(outputMsg))
+
+        if contentType == "application/protobuf":
+            return nimtwirp.newResponse(serialize(outputMsg))
+        elif contentType == "application/json":
+            return nimtwirp.newResponse(toJson(outputMsg))
 """
 
     result &= &"""
@@ -81,10 +92,15 @@ proc genClient(service: Service, prefix: string): string =
 type
     {service.name}Client* = ref object of nimtwirp.Client
 
-proc new{service.name}Client*(address: string): {service.name}Client =
+proc new{service.name}Client*(address: string, kind = ClientKind.Protobuf): {service.name}Client =
     new(result)
     result.client = newHttpClient()
-    result.client.headers = newHttpHeaders({{"Content-Type": "application/protobuf"}})
+    result.kind = kind
+    case kind
+    of ClientKind.Protobuf:
+        result.client.headers = newHttpHeaders({{"Content-Type": "application/protobuf"}})
+    of ClientKind.Json:
+        result.client.headers = newHttpHeaders({{"Content-Type": "application/json"}})
     result.address = address
 
 """
@@ -92,9 +108,18 @@ proc new{service.name}Client*(address: string): {service.name}Client =
     for meth in service.methods:
         result &= &"""
 proc {meth.name}*(client: {service.name}Client, req: {meth.inputType}): {meth.outputType} =
-    let body = serialize(req)
+    var body: string
+    case client.kind
+    of ClientKind.Protobuf:
+        body = serialize(req)
+    of ClientKind.Json:
+        body = $toJson(req)
     let resp = request(client, {service.name}Prefix, "{meth.name}", body)
-    result = new{meth.outputType}(resp.body)
+    case client.kind
+    of ClientKind.Protobuf:
+        result = new{meth.outputType}(resp.body)
+    of ClientKind.Json:
+        result = parse{meth.outputType}(parseJson(resp.body))
 
 """
 
diff --git a/nimtwirp/nimtwirp.nim b/nimtwirp/nimtwirp.nim
index f3fa29d..242e2f1 100644
--- a/nimtwirp/nimtwirp.nim
+++ b/nimtwirp/nimtwirp.nim
@@ -23,6 +23,11 @@ type
     Client* = ref object of RootObj
         client*: HttpClient
         address*: string
+        kind*: ClientKind
+
+    ClientKind* {.pure.} = enum
+        Protobuf
+        Json
 
 proc respond*(req: asynchttpserver.Request, resp: nimtwirp.Response): Future[void] =
     req.respond(resp.code, resp.body, resp.headers)
@@ -46,6 +51,13 @@ proc newResponse*(body: string): nimtwirp.Response =
     result.body = body
     result.headers = newHttpHeaders({"Content-Type": "application/protobuf"})
 
+proc newResponse*(node: JsonNode): nimtwirp.Response =
+    new(result)
+    result.code = Http200
+    result.body = newStringOfCap(512)
+    toUgly(result.body, node)
+    result.headers = newHttpHeaders({"Content-Type": "application/json"})
+
 proc handleHttpRequest(request: asynchttpserver.Request, handler: ServeHandlerProc) {.async.} =
     var fut = handler(request)
 
@@ -124,9 +136,10 @@ proc validateRequest*(request: asynchttpserver.Request, prefix: string): tuple[c
 
     result.contentType = getOrDefault(request.headers, "Content-Type")
 
-    if result.contentType != "application/protobuf":
+    if result.contentType != "application/protobuf" and
+       result.contentType != "application/json":
         raise newTwirpError(TwirpInternal,
-            "expected Content-Type to be application/protobuf instead of " &
+            "expected Content-Type to be application/protobuf or application/json instead of " &
             result.contentType)
 
     if not startsWith(request.url.path, prefix):