Fix subscription handler (#175)

* Fix contract_dsl event response parser

* Fix pending subscription event handler

* Use useDefaultSerializationIn for EventData

Surprisingly the pending event bug not detected when using ganache. It only manifest after migrated to hardhat. Also not detected on linux and windows CI. Only on macos amd64 CI, and sometimes on macos arm64 CI. Probably related to async timing trigger pending event?. But it's a genuine bug, dated back far before migration from stdlib/json to json-serialization.

web3.nim

@@ -87,28 +87,18 @@ func getValue(params: RequestParamsRx, field: string, FieldType: type):
   except CatchableError as exc:
     return err(exc.msg)
 
-func toJsonString(params: RequestParamsRx):
-       Result[JsonString, string] {.gcsafe, raises: [].} =
-  try:
-    let res = JrpcSys.encode(params.toTx)
-    return ok(res.JsonString)
-  except CatchableError as exc:
-    return err(exc.msg)
-
 proc handleSubscriptionNotification(w: Web3, params: RequestParamsRx):
                                 Result[void, string] {.gcsafe, raises: [].} =
   let subs = params.getValue("subscription", string).valueOr:
     return err(error)
   let s = w.subscriptions.getOrDefault(subs)
   if not s.isNil and not s.removed:
+    let res = params.getValue("result", JsonString).valueOr:
+      return err(error)
     if s.historicalEventsProcessed:
-      let res = params.getValue("result", JsonString).valueOr:
-        return err(error)
       s.eventHandler(res)
     else:
-      let par = params.toJsonString().valueOr:
-        return err(error)
-      s.pendingEvents.add(par)
+      s.pendingEvents.add(res)
 
   ok()
 

web3/contract_dsl.nim

@@ -2,6 +2,7 @@ import
   std/[macros, strutils],
   json_serialization,
   ./[encoding, eth_api_types],
+  ./conversions,
   stint,
   stew/byteutils
 
@@ -40,6 +41,12 @@ type
     of constructor: constructorObject: ConstructorObject
     of event: eventObject: EventObject
 
+  EventData* = object
+    data*: seq[byte]
+    topics*: seq[Bytes32]
+
+EventData.useDefaultSerializationIn JrpcConv
+
 proc joinStrings(s: varargs[string]): string = join(s)
 
 proc unknownType() = discard # Used for informative errors
@@ -233,7 +240,7 @@ proc genEvent(cname: NimNode, eventObject: EventObject): NimNode =
   if not eventObject.anonymous:
     let callbackIdent = ident "callback"
     let jsonIdent = ident "j"
-    let jsonData = ident "jsonData"
+    let eventData = ident "eventData"
     var
       params = nnkFormalParams.newTree(newEmptyNode())
       paramsWithRawData = nnkFormalParams.newTree(newEmptyNode())
@@ -243,10 +250,9 @@ proc genEvent(cname: NimNode, eventObject: EventObject): NimNode =
       call = nnkCall.newTree(callbackIdent)
       callWithRawData = nnkCall.newTree(callbackIdent)
       offset = ident "offset"
-      inputData = ident "inputData"
 
     argParseBody.add quote do:
-      let `jsonData` = JrpcConv.decode(`jsonIdent`.string, JsonNode)
+      let `eventData` = JrpcConv.decode(`jsonIdent`.string, EventData)
 
     var offsetInited = false
 
@@ -264,19 +270,18 @@ proc genEvent(cname: NimNode, eventObject: EventObject): NimNode =
       if input.indexed:
         argParseBody.add quote do:
           var `argument`: `kind`
-          discard decode(hexToSeqByte(`jsonData`["topics"][`i`].getStr), 0, 0, `argument`)
+          discard decode(`eventData`.topics[`i`].data, 0, 0, `argument`)
         i += 1
       else:
         if not offsetInited:
           argParseBody.add quote do:
-            var `inputData` = hexToSeqByte(`jsonData`["data"].getStr)
             var `offset` = 0
 
           offsetInited = true
 
         argParseBody.add quote do:
           var `argument`: `kind`
-          `offset` += decode(`inputData`, 0, `offset`, `argument`)
+          `offset` += decode(`eventData`.data, 0, `offset`, `argument`)
       call.add argument
       callWithRawData.add argument
     let