Send async data to template with deferrable

README.md

@@ -7,7 +7,7 @@ Enables asynchronous DOM updates with no Javascript needed!
 ## Test
 
 ```shell
-go test ./...
+go test -race ./...
 ```
 
 ## Run

internal/app/index.go

@@ -1,11 +1,16 @@
 package app
 
 import (
+	"github.com/initialcapacity/go-streaming/pkg/deferrable"
 	"github.com/initialcapacity/go-streaming/pkg/websupport"
 	"net/http"
 	"time"
 )
 
+type model struct {
+	Message deferrable.Defer[chan []string]
+}
+
 func Index(addArtificialDelay bool) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		data := make(chan []string)
@@ -22,6 +27,6 @@ func Index(addArtificialDelay bool) http.HandlerFunc {
 			close(data)
 		}()
 
-		_ = websupport.Render(w, Resources, "index", data)
+		_ = websupport.Render(w, Resources, "index", model{Message: deferrable.New(w, data)})
 	}
 }

internal/app/resources/templates/index.gohtml

@@ -19,7 +19,7 @@
             </slot>
         </section>
     </template>
-    {{ range $items := . }}
+    {{ range $items := .Message.Value }}
         <div slot="content">
             <h2>
                 Success!

pkg/deferrable/deferrable.go

@@ -0,0 +1,20 @@
+package deferrable
+
+import "net/http"
+
+type Defer[T any] struct {
+	writer http.ResponseWriter
+	value  T
+}
+
+func New[T any](writer http.ResponseWriter, value T) Defer[T] {
+	return Defer[T]{
+		writer: writer,
+		value:  value,
+	}
+}
+
+func (d Defer[T]) Value() T {
+	_ = http.NewResponseController(d.writer).Flush()
+	return d.value
+}

pkg/websupport/render.go

@@ -12,24 +12,7 @@ func Render(writer http.ResponseWriter, resources fs.FS, templateName string, da
 
 	writer.Header().Set("Transfer-Encoding", "chunked")
 	temp := template.Must(template.New(fileName).
-		Funcs(template.FuncMap{
-			"flush": func(value any) any {
-				go func() {
-					// flush immediately after the value is returned
-					// TODO: address the data race
-					_ = flush(writer)
-				}()
-
-				return value
-			},
-		}).
 		ParseFS(resources, "resources/templates/template.gohtml", fmt.Sprintf("resources/templates/%s", fileName)))
 
-	AddFlush(temp)
-
 	return temp.Execute(writer, data)
 }
-
-func flush(writer http.ResponseWriter) error {
-	return http.NewResponseController(writer).Flush()
-}