From aeb208162f278961283252c878ac902b63687091 Mon Sep 17 00:00:00 2001
From: Jerko Steiner <jerko.steiner@gmail.com>
Date: Sun, 4 Aug 2019 13:01:33 +0700
Subject: [PATCH] Refactor express#handleError

---
 packages/jsonrpc/src/express.test.ts |  1 -
 packages/jsonrpc/src/express.ts      | 65 ++++++++++++++++------------
 2 files changed, 37 insertions(+), 29 deletions(-)

diff --git a/packages/jsonrpc/src/express.test.ts b/packages/jsonrpc/src/express.test.ts
index df3e0b5..d0a717d 100644
--- a/packages/jsonrpc/src/express.test.ts
+++ b/packages/jsonrpc/src/express.test.ts
@@ -91,7 +91,6 @@ describe('jsonrpc', () => {
         params: ['test'],
       })
       .expect(500)
-      expect(response.body.id).toEqual(1)
       expect(response.body).toEqual({
         jsonrpc: '2.0',
         id: 1,
diff --git a/packages/jsonrpc/src/express.ts b/packages/jsonrpc/src/express.ts
index 7a2b231..7d76bba 100644
--- a/packages/jsonrpc/src/express.ts
+++ b/packages/jsonrpc/src/express.ts
@@ -1,8 +1,11 @@
+import express, {ErrorRequestHandler} from 'express'
 import {FunctionPropertyNames} from './types'
-import {NextFunction, Request, Response, Router} from 'express'
-import {createRpcService, ERROR_SERVER, ERROR_INVALID_PARAMS} from './jsonrpc'
-import {createError, isJSONRPCError, IJSONRPCError} from './error'
 import {IDEMPOTENT_METHOD_REGEX} from './idempotent'
+import {IErrorResponse} from './jsonrpc'
+import {ISuccessResponse} from './jsonrpc'
+import {NextFunction, Request, Response, Router} from 'express'
+import {createError, isJSONRPCError, IJSONRPCError, IError} from './error'
+import {createRpcService, ERROR_SERVER, ERROR_INVALID_PARAMS} from './jsonrpc'
 
 export type TGetContext<Context> = (req: Request) => Context
 
@@ -23,7 +26,10 @@ export function jsonrpc<Context>(
 
       const router = Router()
 
-      function handleResponse(response: any, res: Response) {
+      function handleResponse(
+        response: ISuccessResponse<unknown> | null,
+        res: Response,
+      ) {
         if (response === null) {
           // notification
           res.status(204).send()
@@ -58,31 +64,34 @@ export function jsonrpc<Context>(
       return router
     },
   }
-}
 
-function handleError(
-  err: any,
-  req: Request,
-  res: Response,
-  next: NextFunction,
-) {
-  const id = req.method === 'POST' ? req.body.id : req.query.id
-  // TODO log error
-  // TODO make this nicer
+  const handleError: ErrorRequestHandler = (err, req, res, next) => {
+    // TODO log error
 
-  const error: IJSONRPCError<unknown> = isJSONRPCError(err)
-    ? err
-    : createError({
-      code: ERROR_SERVER.code,
-      message: err.statusCode >= 400 && err.statusCode < 500
-        ? err.message
-        : ERROR_SERVER.message,
-    }, {
+    if (isJSONRPCError(err)) {
+      res.status(err.statusCode)
+      res.json(err.response)
+      return
+    }
+
+    const id = getRequestId(req)
+    const statusCode: number = err.statusCode || 500
+    const errorResponse: IErrorResponse<unknown> = {
+      jsonrpc: '2.0',
       id,
-      data: null,
-      statusCode: err.statusCode || 500,
-    })
-
-  res.status(error.statusCode)
-  res.json(error.response)
+      result: null,
+      error: {
+        code: ERROR_SERVER.code,
+        message: statusCode >= 500 ? ERROR_SERVER.message : err.message,
+        data: 'errors' in err ? err.errors : null,
+      },
+    }
+    res.status(statusCode)
+    res.json(errorResponse)
+  }
+}
+
+function getRequestId(req: express.Request) {
+  const id = req.method === 'POST' ? req.body.id : req.query.id
+  return id !== undefined ? id : null
 }