fix: missing error message when return HTTPResult (#785)

* fix: missing error message when return HTTPResult

Signed-off-by: wenfeng <[email protected]>

* fmt: goimport

Signed-off-by: wenfeng <[email protected]>

* update according to reviewer's advice

Signed-off-by: wenfeng <[email protected]>

samples/http/receiver-result/main.go

@@ -0,0 +1,39 @@
+/*
+ Copyright 2022 The CloudEvents Authors
+ SPDX-License-Identifier: Apache-2.0
+*/
+
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net/http"
+
+	cloudevents "github.com/cloudevents/sdk-go/v2"
+)
+
+func main() {
+	ctx := context.Background()
+	p, err := cloudevents.NewHTTP()
+	if err != nil {
+		log.Fatalf("failed to create protocol: %s", err.Error())
+	}
+
+	c, err := cloudevents.NewClient(p)
+	if err != nil {
+		log.Fatalf("failed to create client, %v", err)
+	}
+
+	log.Printf("will listen on :8080\n")
+	log.Fatalf("failed to start receiver: %s", c.StartReceiver(ctx, receive))
+}
+
+func receive(ctx context.Context, event cloudevents.Event) cloudevents.Result {
+	fmt.Printf("%s", event)
+	if event.Type() != "com.cloudevents.sample.sent" {
+		return cloudevents.NewHTTPResult(http.StatusBadRequest, "invalid type of %s", event.Type())
+	}
+	return cloudevents.NewHTTPResult(http.StatusOK, "")
+}

samples/http/sender-protobuf/main.go

@@ -42,8 +42,9 @@ func main() {
 			var httpResult *cehttp.Result
 			if cloudevents.ResultAs(res, &httpResult) {
 				log.Printf("Sent %d with status code %d", i, httpResult.StatusCode)
+			} else {
+				log.Printf("Send did not return an HTTP response: %s", res)
 			}
-			log.Printf("Send did not return an HTTP response: %s", res)
 		}
 	}
 }

samples/http/sender/main.go

@@ -7,7 +7,9 @@ package main
 
 import (
 	"context"
+	"fmt"
 	"log"
+	"net/http"
 
 	cloudevents "github.com/cloudevents/sdk-go/v2"
 	cehttp "github.com/cloudevents/sdk-go/v2/protocol/http"
@@ -40,8 +42,15 @@ func main() {
 			log.Printf("Failed to send: %v", res)
 		} else {
 			var httpResult *cehttp.Result
-			cloudevents.ResultAs(res, &httpResult)
-			log.Printf("Sent %d with status code %d", i, httpResult.StatusCode)
+			if cloudevents.ResultAs(res, &httpResult) {
+				var err error
+				if httpResult.StatusCode != http.StatusOK {
+					err = fmt.Errorf(httpResult.Format, httpResult.Args...)
+				}
+				log.Printf("Sent %d with status code %d, error: %v", i, httpResult.StatusCode, err)
+			} else {
+				log.Printf("Send did not return an HTTP response: %s", res)
+			}
 		}
 	}
 }

v2/protocol/http/protocol.go

@@ -359,14 +359,15 @@ func (p *Protocol) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 		}
 
 		status := http.StatusOK
+		var errMsg string
 		if res != nil {
 			var result *Result
 			switch {
 			case protocol.ResultAs(res, &result):
 				if result.StatusCode > 100 && result.StatusCode < 600 {
 					status = result.StatusCode
 				}
-
+				errMsg = fmt.Errorf(result.Format, result.Args...).Error()
 			case !protocol.IsACK(res):
 				// Map client errors to http status code
 				validationError := event.ValidationError{}
@@ -390,6 +391,9 @@ func (p *Protocol) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 		}
 
 		rw.WriteHeader(status)
+		if _, err := rw.Write([]byte(errMsg)); err != nil {
+			return err
+		}
 		return nil
 	}