Treat empty hash as nil

README.org

@@ -10,6 +10,22 @@ https://pypi.org/project/template-nest/.
 
 * News
 
+** v0.1.6 - 2025-12-02
+
++ Treat empty hash as nil
+
+  Tom: I think that if go's behaviour is to insert an empty map when nil is
+  returned as a templatenest.Hash, then we need to change the templatenest
+  behaviour to regard an empty map as being nil.
+
+** v0.1.5 - 2025-02-22
+
++ Handle all pointer types generically.
+
+** v0.1.4 - 2025-01-09
+
++ Fix nil pointer dereference error.
+
 ** v0.1.3 - 2024-11-24
 
 + Fix handling of numeric types.

template_nest.go

@@ -279,6 +279,19 @@ func (nest *TemplateNest) MustRender(toRender interface{}) string {
 }
 
 func (nest *TemplateNest) Render(toRender interface{}) (string, error) {
+	if toRender == nil {
+		return "", nil
+	}
+
+	// Handle pointer types generically
+	if reflect.TypeOf(toRender).Kind() == reflect.Ptr {
+		if reflect.ValueOf(toRender).IsNil() {
+			return "", nil
+		}
+		// Dereference the pointer and recursively call Render
+		return nest.Render(reflect.ValueOf(toRender).Elem().Interface())
+	}
+
 	if reflect.TypeOf(toRender).Kind() == reflect.Slice {
 		return nest.renderSlice(toRender)
 	}
@@ -351,10 +364,15 @@ func (nest *TemplateNest) renderSlice(toRender interface{}) (string, error) {
 }
 
 func (nest *TemplateNest) renderHash(hash map[string]interface{}) (string, error) {
+	// If the hash is completely empty, return an empty string.
+	if len(hash) == 0 {
+		return "", nil
+	}
+
 	tLabel, ok := hash[*nest.option.NameLabel]
 	if !ok {
 		return "", fmt.Errorf(
-			"encountered hash with no name label (name label: `%s`)", nest.option.NameLabel,
+			"encountered hash with no name label (name label: `%+v`)", nest.option.NameLabel,
 		)
 	}
 

tests/01_render_test.go

@@ -174,6 +174,19 @@ func TestRenderNoNameLabel(t *testing.T) {
 	}
 }
 
+func TestRenderEmptyHash(t *testing.T) {
+	nest, err := templatenest.New(templatenest.Option{TemplateDir: "templates"})
+	if err != nil {
+		t.Fatalf("Failed to initialize TemplateNest: %+v", err)
+	}
+
+	page := templatenest.Hash{}
+
+	render, err := nest.Render(page)
+	assert.Nil(t, err)
+	assert.Equal(t, "", render)
+}
+
 func TestRenderSimplePageArrays(t *testing.T) {
 	nest, err := templatenest.New(templatenest.Option{
 		TemplateDir:   "templates",