added subscription.Message.WriteSSE method

tools/subscriptions/client.go

@@ -13,12 +13,6 @@ import (
 
 const optionsParam = "options"
 
-// Message defines a client's channel data.
-type Message struct {
-	Name string `json:"name"`
-	Data []byte `json:"data"`
-}
-
 // SubscriptionOptions defines the request options (query params, headers, etc.)
 // for a single subscription topic.
 type SubscriptionOptions struct {

tools/subscriptions/message.go

@@ -0,0 +1,37 @@
+package subscriptions
+
+import (
+	"io"
+)
+
+// Message defines a client's channel data.
+type Message struct {
+	Name string `json:"name"`
+	Data []byte `json:"data"`
+}
+
+// WriteSSE writes the current message in a SSE format into the provided writer.
+//
+// For example, writing to a router.Event:
+//
+//	m := Message{Name: "users/create", Data: []byte{...}}
+//	m.Write(e.Response, "yourEventId")
+//	e.Flush()
+func (m *Message) WriteSSE(w io.Writer, eventId string) error {
+	parts := [][]byte{
+		[]byte("id:" + eventId + "\n"),
+		[]byte("event:" + m.Name + "\n"),
+		[]byte("data:"),
+		m.Data,
+		[]byte("\n\n"),
+	}
+
+	for _, part := range parts {
+		_, err := w.Write(part)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

tools/subscriptions/message_test.go

@@ -0,0 +1,25 @@
+package subscriptions_test
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/pocketbase/pocketbase/tools/subscriptions"
+)
+
+func TestMessageWrite(t *testing.T) {
+	m := subscriptions.Message{
+		Name: "test_name",
+		Data: []byte("test_data"),
+	}
+
+	var sb strings.Builder
+
+	m.WriteSSE(&sb, "test_id")
+
+	expected := "id:test_id\nevent:test_name\ndata:test_data\n\n"
+
+	if v := sb.String(); v != expected {
+		t.Fatalf("Expected writer content\n%q\ngot\n%q", expected, v)
+	}
+}