Implement NewHTTPRequestFromEvents

Now you can send batch events with your very own http.Client.

Signed-off-by: Mark Mandel <markmandel@google.com>

v2/alias.go

@@ -139,6 +139,7 @@ var (
 	NewEventFromHTTPResponse  = http.NewEventFromHTTPResponse
 	NewEventsFromHTTPRequest  = http.NewEventsFromHTTPRequest
 	NewEventsFromHTTPResponse = http.NewEventsFromHTTPResponse
+	NewHTTPRequestFromEvents  = http.NewHTTPRequestFromEvents
 
 	// HTTP Messages
 

v2/protocol/http/utility.go

@@ -6,7 +6,9 @@
 package http
 
 import (
+	"bytes"
 	"context"
+	"encoding/json"
 	nethttp "net/http"
 
 	"github.com/cloudevents/sdk-go/v2/binding"
@@ -36,3 +38,27 @@ func NewEventsFromHTTPResponse(resp *nethttp.Response) ([]event.Event, error) {
 	msg := NewMessageFromHttpResponse(resp)
 	return binding.ToEvents(context.Background(), msg, msg.BodyReader)
 }
+
+// NewHTTPRequestFromEvents creates a http.Request object that can be used with any http.Client.
+func NewHTTPRequestFromEvents(ctx context.Context, url string, events []event.Event) (*nethttp.Request, error) {
+	// Sending batch events is quite straightforward, as there is only JSON format, so a simple implementation.
+	for _, e := range events {
+		if err := e.Validate(); err != nil {
+			return nil, err
+		}
+	}
+	var buffer bytes.Buffer
+	err := json.NewEncoder(&buffer).Encode(events)
+	if err != nil {
+		return nil, err
+	}
+
+	request, err := nethttp.NewRequestWithContext(ctx, nethttp.MethodPost, url, &buffer)
+	if err != nil {
+		return nil, err
+	}
+
+	request.Header.Set(ContentType, event.ApplicationCloudEventsBatchJSON)
+
+	return request, nil
+}

v2/protocol/http/utility_test.go

@@ -14,11 +14,11 @@ import (
 	"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"
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/require"
 )
 
 func TestNewEventFromHttpRequest(t *testing.T) {
@@ -115,3 +115,42 @@ func TestNewEventsFromHTTPResponse(t *testing.T) {
 	require.Len(t, events, 1)
 	test.AssertEvent(t, events[0], test.IsValid())
 }
+
+func TestNewHTTPRequestFromEvents(t *testing.T) {
+	var events []event.Event
+	e := event.New()
+	e.SetID(uuid.New().String())
+	e.SetSource("example/uri")
+	e.SetType("example.type")
+	require.NoError(t, e.SetData(event.ApplicationJSON, map[string]string{"hello": "world"}))
+	events = append(events, e.Clone())
+
+	e.SetID(uuid.New().String())
+	require.NoError(t, e.SetData(event.ApplicationJSON, map[string]string{"goodbye": "world"}))
+	events = append(events, e)
+
+	require.Len(t, events, 2)
+	require.NotEqual(t, events[0], events[1])
+
+	// echo back what we get, so we can compare events at either side.
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set(ContentType, r.Header.Get(ContentType))
+		b, err := io.ReadAll(r.Body)
+		require.NoError(t, err)
+		require.NoError(t, r.Body.Close())
+		_, err = w.Write(b)
+		require.NoError(t, err)
+	}))
+	defer ts.Close()
+
+	req, err := NewHTTPRequestFromEvents(context.Background(), ts.URL, events)
+	require.NoError(t, err)
+
+	resp, err := ts.Client().Do(req)
+	require.NoError(t, err)
+
+	result, err := NewEventsFromHTTPResponse(resp)
+	require.NoError(t, err)
+
+	require.Equal(t, events, result)
+}