fix: struct error

Author: franklinkim

error.go

@@ -34,11 +34,15 @@ func NewError(err error) *Error {
 
 	// retrieve error details
 	errType := reflect.TypeOf(err)
+	errElem := errType
+	if errType.Kind() == reflect.Ptr {
+		errElem = errType.Elem()
+	}
 
 	inst := &Error{
 		Msg:  err.Error(),
 		Type: errType.String(),
-		Pkg:  errType.Elem().PkgPath(),
+		Pkg:  errElem.PkgPath(),
 		Data: err,
 	}
 
@@ -80,9 +84,9 @@ func (e *Error) Format(s fmt.State, verb rune) {
 	switch verb {
 	case 'v':
 		if s.Flag('+') {
-			fmt.Fprintf(s, "%s.(%s)\n", e.Pkg, e.Type)
+			_, _ = fmt.Fprintf(s, "%s.(%s)\n", e.Pkg, e.Type)
 			if e.Data != nil {
-				fmt.Fprintf(s, "Data: %v\n", e.Data)
+				_, _ = fmt.Fprintf(s, "Data: %v\n", e.Data)
 			}
 		}
 		fallthrough
@@ -106,10 +110,14 @@ func (e *Error) Is(err error) bool {
 	}
 
 	errType := reflect.TypeOf(err)
+	errElem := errType
+	if errType.Kind() == reflect.Ptr {
+		errElem = errType.Elem()
+	}
 
 	if e.Msg == err.Error() &&
 		errType.String() == e.Type &&
-		errType.Elem().PkgPath() == e.Pkg {
+		errElem.PkgPath() == e.Pkg {
 		return true
 	}
 

example/errors/handler/backend/handler.go

@@ -10,6 +10,14 @@ import (
 
 type (
 	ScalarError string
+	StructError struct {
+		Msg    string
+		Map    map[string]string
+		Slice  []string
+		Struct struct {
+			A string
+		}
+	}
 	CustomError struct {
 		Msg    string
 		Map    map[string]string
@@ -33,6 +41,19 @@ func (e *ScalarError) Error() string {
 	return string(*e)
 }
 
+func NewStructError(msg string) StructError {
+	return StructError{
+		Msg:    msg,
+		Map:    map[string]string{"a": "b"},
+		Slice:  []string{"a", "b"},
+		Struct: struct{ A string }{A: "b"},
+	}
+}
+
+func (e StructError) Error() string {
+	return e.Msg
+}
+
 func NewCustomError(msg string) *CustomError {
 	return &CustomError{
 		Msg:    msg,
@@ -86,6 +107,10 @@ func (h *Handler) TypedError(w http.ResponseWriter, r *http.Request) (e error) {
 	return ErrTyped
 }
 
+func (h *Handler) StructError(w http.ResponseWriter, r *http.Request) (e error) {
+	return NewStructError("struct error")
+}
+
 func (h *Handler) ScalarError(w http.ResponseWriter, r *http.Request) (e error) {
 	return NewScalarError(ScalarErrorOne)
 }

example/errors/main.go

@@ -147,6 +147,28 @@ func call() {
 		}
 	}
 
+	{
+		fmt.Println("--- StructError ----------------")
+		var structErr backend.StructError
+		var gotsrpcErr *gotsrpc.Error
+		serviceErr, err := c.StructError(ctx)
+		if err != nil {
+			panic("client error should be nil")
+		} else if serviceErr == nil {
+			panic("service error should not be nil")
+		} else if serviceErr != nil {
+			fmt.Printf("%s\n", serviceErr)
+			fmt.Printf("%q\n", serviceErr)
+			fmt.Printf("%+v\n", serviceErr)
+		}
+		if errors.As(serviceErr, &gotsrpcErr) {
+			fmt.Println(gotsrpcErr)
+		}
+		if errors.As(serviceErr, &structErr) {
+			fmt.Println(structErr)
+		}
+	}
+
 	{
 		fmt.Println("--- CustomError ----------------")
 		var customErr *backend.CustomError

example/errors/service/backend/gotsrpc_gen.go

@@ -54,6 +54,7 @@ type Service interface {
 	Scalar(w http.ResponseWriter, r *http.Request) (e *ScalarError)
 	MultiScalar(w http.ResponseWriter, r *http.Request) (e *MultiScalar)
 	Struct(w http.ResponseWriter, r *http.Request) (e *StructError)
+	StructError(w http.ResponseWriter, r *http.Request) (e error)
 	TypedError(w http.ResponseWriter, r *http.Request) (e error)
 	ScalarError(w http.ResponseWriter, r *http.Request) (e error)
 	CustomError(w http.ResponseWriter, r *http.Request) (e error)

example/errors/service/backend/gotsrpcclient_gen.go

@@ -120,7 +120,7 @@ func Reply(response []interface{}, stats *CallStats, r *http.Request, w http.Res
 		if len(response) > 0 {
 			errResp := response[len(response)-1]
 			if v, ok := errResp.(error); ok && v != nil {
-				if !reflect.ValueOf(v).IsNil() {
+				if !reflect.ValueOf(v).IsZero() {
 					stats.ErrorCode = 1
 					stats.ErrorType = fmt.Sprintf("%T", v)
 					stats.ErrorMessage = v.Error()

example/errors/service/backend/service.go

@@ -33,7 +33,7 @@ var msgpackClientHandle = &clientHandle{
 	beforeEncodeReply: func(resp *[]interface{}) error {
 		for k, v := range *resp {
 			if e, ok := v.(error); ok {
-				if r := reflect.ValueOf(e); !r.IsNil() {
+				if r := reflect.ValueOf(e); !r.IsZero() {
 					(*resp)[k] = NewError(e)
 				}
 			}
@@ -43,7 +43,11 @@ var msgpackClientHandle = &clientHandle{
 	beforeDecodeReply: func(reply []interface{}) ([]interface{}, error) {
 		ret := make([]interface{}, len(reply))
 		for k, v := range reply {
-			if reflect.TypeOf(v).Elem().Implements(errorType) {
+			val := reflect.TypeOf(v)
+			if val.Kind() == reflect.Ptr {
+				val = val.Elem()
+			}
+			if val.Implements(errorType) {
 				var e *Error
 				ret[k] = e
 			} else {