From 248a208af896de857954e8c64f3e32a4c2cf7dc7 Mon Sep 17 00:00:00 2001
From: Mathieu Corbin <mathieu.corbin@qonto.com>
Date: Fri, 1 Jul 2022 14:14:56 +0200
Subject: [PATCH] Allow to retrieve bindHook errors

The original error returned by bindHook is currently lost.
I have use cases where I need to access this error details in order to
return specific error messages to end users.

This commit adds the ability to retrieve the bindHook error from the
BindError struct.
---
 tonic/handler.go | 2 +-
 tonic/tonic.go   | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/tonic/handler.go b/tonic/handler.go
index bcb99e8..6664bc6 100644
--- a/tonic/handler.go
+++ b/tonic/handler.go
@@ -73,7 +73,7 @@ func Handler(h interface{}, status int, options ...func(*Route)) gin.HandlerFunc
 			input := reflect.New(in)
 			// Bind the body with the hook.
 			if err := bindHook(c, input.Interface()); err != nil {
-				handleError(c, BindError{message: err.Error(), typ: in})
+				handleError(c, BindError{message: err.Error(), typ: in, bindHookErr: err})
 				return
 			}
 			// Bind query-parameters.
diff --git a/tonic/tonic.go b/tonic/tonic.go
index 8bc9290..95ed72c 100644
--- a/tonic/tonic.go
+++ b/tonic/tonic.go
@@ -230,6 +230,7 @@ func Tags(tags []string) func(*Route) {
 // to bind parameters, to differentiate from errors returned
 // by the handlers.
 type BindError struct {
+	bindHookErr   error
 	validationErr error
 	message       string
 	typ           reflect.Type
@@ -258,6 +259,11 @@ func (be BindError) ValidationErrors() validator.ValidationErrors {
 	return nil
 }
 
+// BindHookError returns the error from the bind process.
+func (be BindError) BindHookError() error {
+	return be.bindHookErr
+}
+
 // An extractorFunc extracts data from a gin context according to
 // parameters specified in a field tag.
 type extractor func(*gin.Context, string) (string, []string, error)