From aa67bc32442e15e46654fb62d02b4a4daf723331 Mon Sep 17 00:00:00 2001
From: Jacques Yakoub <jacques.yakoub@gmail.com>
Date: Mon, 2 Dec 2019 21:49:48 +0100
Subject: [PATCH] Better handling of MulterError

---
 src/middlewares/openapi.multipart.ts | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/middlewares/openapi.multipart.ts b/src/middlewares/openapi.multipart.ts
index 6a569faa..1c1b1aa8 100644
--- a/src/middlewares/openapi.multipart.ts
+++ b/src/middlewares/openapi.multipart.ts
@@ -70,7 +70,17 @@ function isMultipart(req: OpenApiRequest): boolean {
 
 function error(req: OpenApiRequest, err: Error): ValidationError {
   if (err instanceof multer.MulterError) {
-    // TODO is special handling for MulterErrors needed
+    // distinguish common errors :
+    // - 413 ( Request Entity Too Large ) : Too many parts / File too large / Too many files
+    // - 400 ( Bad Request ) : Field * too long / Too many fields
+    // - 500 ( Internal Server Error ) : Unexpected field
+    const payload_too_big = /LIMIT_(FILE|PART)_(SIZE|COUNT)/.test(err.code);
+    const unexpected = /LIMIT_UNEXPECTED_FILE/.test(err.code);
+    const status = (payload_too_big) 
+          ? 413 
+          : (!unexpected)
+              ? 400
+              : 500;
     return validationError(500, req.path, err.message);
   } else {
     // HACK