Helper function to create event from HTTP Request or Response (#799)

* Helper function to create event from HTTP Request or Response

* Add missing use of encoding options and remove redundant function call

Signed-off-by: Adam Ross <adamross@google.com>

* Update v2/protocol/http/utility.go

Co-authored-by: Scott Nichols <n3wscott@tableflip.dev>

* Update v2/protocol/http/utility.go

Co-authored-by: Scott Nichols <n3wscott@tableflip.dev>

* Update v2/protocol/http/utility.go

Co-authored-by: Scott Nichols <n3wscott@tableflip.dev>

* Update v2/protocol/http/utility.go

Co-authored-by: Scott Nichols <n3wscott@tableflip.dev>

* capitalize HTTP and WIP clean-up

Signed-off-by: Adam Ross <adamross@google.com>

Signed-off-by: Adam Ross <adamross@google.com>
Co-authored-by: Scott Nichols <n3wscott@tableflip.dev>

README.md

@@ -83,6 +83,19 @@ func main() {
 }
 ```
 
+## Create a CloudEvent from an HTTP Request
+
+```go
+func handler(w http.ResponseWriter, r *http.Request) {
+	event, err := cloudevents.NewCloudEventFromHTTPRequest(r)
+	if err != nil {
+		log.Print("failed to parse CloudEvent from request: %v", err)
+		http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
+	}
+	w.Write([]byte(*event.String()))
+}
+```
+
 ## Serialize/Deserialize a CloudEvent
 
 To marshal a CloudEvent into JSON:

docs/index.md

@@ -81,6 +81,19 @@ func main() {
 }
 ```
 
+## Create a CloudEvent from an HTTP Request
+
+```go
+func handler(w http.ResponseWriter, r *http.Request) {
+	event, err := cloudevents.NewCloudEventFromHTTPRequest(r)
+	if err != nil {
+		log.Print("failed to parse CloudEvent from request: %v", err)
+		http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
+	}
+	w.Write([]byte(*event.String()))
+}
+```
+
 ## Serialize/Deserialize a CloudEvent
 
 To marshal a CloudEvent into JSON:

v2/alias.go

@@ -134,6 +134,10 @@ var (
 
 	ToMessage = binding.ToMessage
 
+	// Event Creation
+	NewEventFromHTTPRequest  = http.NewEventFromHTTPRequest
+	NewEventFromHTTPResponse = http.NewEventFromHTTPResponse
+
 	// HTTP Messages
 
 	WriteHTTPRequest = http.WriteRequest

v2/protocol/http/utility.go

@@ -0,0 +1,26 @@
+/*
+ Copyright 2022 The CloudEvents Authors
+ SPDX-License-Identifier: Apache-2.0
+*/
+
+package http
+
+import (
+	"context"
+	nethttp "net/http"
+
+	"github.com/cloudevents/sdk-go/v2/binding"
+	"github.com/cloudevents/sdk-go/v2/event"
+)
+
+// NewEventFromHTTPRequest returns an Event.
+func NewEventFromHTTPRequest(req *nethttp.Request) (*event.Event, error) {
+	msg := NewMessageFromHttpRequest(req)
+	return binding.ToEvent(context.Background(), msg)
+}
+
+// NewEventFromHTTPResponse returns an Event.
+func NewEventFromHTTPResponse(resp *nethttp.Response) (*event.Event, error) {
+	msg := NewMessageFromHttpResponse(resp)
+	return binding.ToEvent(context.Background(), msg)
+}

v2/protocol/http/utility_test.go

@@ -0,0 +1,91 @@
+/*
+ Copyright 2022 The CloudEvents Authors
+ SPDX-License-Identifier: Apache-2.0
+*/
+
+package http
+
+import (
+	"bytes"
+	"context"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/cloudevents/sdk-go/v2/binding"
+	"github.com/cloudevents/sdk-go/v2/event"
+	"github.com/cloudevents/sdk-go/v2/test"
+)
+
+func TestNewEventFromHttpRequest(t *testing.T) {
+	tests := []struct {
+		name     string
+		encoding binding.Encoding
+	}{{
+		name:     "Structured encoding",
+		encoding: binding.EncodingStructured,
+	}, {
+		name:     "Binary encoding",
+		encoding: binding.EncodingBinary,
+	}}
+
+	for _, tt := range tests {
+		test.EachEvent(t, test.Events(), func(t *testing.T, eventIn event.Event) {
+			t.Run(tt.name, func(t *testing.T) {
+				ctx := context.TODO()
+				if tt.encoding == binding.EncodingStructured {
+					ctx = binding.WithForceStructured(ctx)
+				} else if tt.encoding == binding.EncodingBinary {
+					ctx = binding.WithForceBinary(ctx)
+				}
+
+				req := httptest.NewRequest("POST", "http://localhost", nil)
+				require.NoError(t, WriteRequest(ctx, (*binding.EventMessage)(&eventIn), req))
+
+				got, err := NewEventFromHTTPRequest(req)
+				require.NoError(t, err)
+				test.AssertEvent(t, *got, test.IsValid())
+			})
+		})
+	}
+}
+
+func TestNewEventFromHttpResponse(t *testing.T) {
+	tests := []struct {
+		name string
+		resp *http.Response
+	}{{
+		name: "Structured encoding",
+		resp: &http.Response{
+			Header: http.Header{
+				"Content-Type": {event.ApplicationCloudEventsJSON},
+			},
+			Body:          ioutil.NopCloser(bytes.NewReader([]byte(`{"data":"foo","datacontenttype":"application/json","id":"id","source":"source","specversion":"1.0","type":"type"}`))),
+			ContentLength: 113,
+		},
+	}, {
+		name: "Binary encoding",
+		resp: &http.Response{
+			Header: func() http.Header {
+				h := http.Header{}
+				h.Set("ce-specversion", "1.0")
+				h.Set("ce-source", "unittest")
+				h.Set("ce-type", "unittest")
+				h.Set("ce-id", "unittest")
+				h.Set("Content-Type", "application/json")
+				return h
+			}(),
+		},
+	}}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := NewEventFromHTTPResponse(tt.resp)
+			require.NoError(t, err)
+			test.AssertEvent(t, *got, test.IsValid())
+		})
+	}
+}