delete element if render fails

Author: linkdata

ui/requestwriter.go

@@ -12,8 +12,12 @@ type RequestWriter struct {
 	io.Writer
 }
 
-func (rqw RequestWriter) UI(ui core.UI, params ...any) error {
-	return rqw.NewElement(ui).JawsRender(rqw, params)
+func (rqw RequestWriter) UI(ui core.UI, params ...any) (err error) {
+	elem := rqw.NewElement(ui)
+	if err = elem.JawsRender(rqw, params); err != nil {
+		rqw.DeleteElement(elem)
+	}
+	return
 }
 
 func (rqw RequestWriter) Write(p []byte) (n int, err error) {

ui/requestwriter_test.go

@@ -3,6 +3,7 @@ package ui
 import (
 	"bytes"
 	"errors"
+	"html/template"
 	"net/http"
 	"net/http/httptest"
 	"strings"
@@ -20,6 +21,14 @@ func (u *testRWUpdater) JawsUpdate(*core.Element) {
 	u.called++
 }
 
+type requestWriterFailGetter struct {
+	err error
+}
+
+func (g requestWriterFailGetter) JawsGetHTML(*core.Element) template.HTML { return "x" }
+func (g requestWriterFailGetter) JawsGetTag(*core.Request) any            { return g }
+func (g requestWriterFailGetter) JawsInit(*core.Element) error            { return g.err }
+
 func newSessionBoundRequest(t *testing.T) (*core.Jaws, *core.Request) {
 	t.Helper()
 	jw, err := core.New()
@@ -143,3 +152,19 @@ func TestErrMissingTemplateAndRWLocker(t *testing.T) {
 		t.Fatal("expected errors.Is match")
 	}
 }
+
+func TestRequestWriterUI_RenderErrorDoesNotLeakElement(t *testing.T) {
+	core.NextJid = 0
+	_, rq := newRequest(t)
+	var buf bytes.Buffer
+	rw := RequestWriter{Request: rq, Writer: &buf}
+
+	renderErr := errors.New("render failed")
+	if err := rw.UI(NewA(requestWriterFailGetter{err: renderErr})); !errors.Is(err, renderErr) {
+		t.Fatalf("want %v got %v", renderErr, err)
+	}
+
+	if leaked := rq.GetElementByJid(1); leaked != nil {
+		t.Fatalf("expected failed render element to be removed from request registry: %v", leaked.Jid())
+	}
+}