Adding ability to set html/template options

README.md

@@ -101,6 +101,7 @@ r := render.New(render.Options{
     UseMutexLock: true, // Overrides the default no lock implementation and uses the standard `sync.RWMutex` lock.
     UnEscapeHTML: true, // Replace ensure '&<>' are output correctly (JSON only).
     StreamingJSON: true, // Streams the JSON response via json.Encoder.
+    HTMLTemplateOption: "missingkey=error", // Sets the option value for HTML templates. See https://pkg.go.dev/html/template#Template.Option for a list of known options.
     RequirePartials: true, // Return an error if a template is missing a partial used in a layout.
     DisableHTTPErrorRendering: true, // Disables automatic rendering of http.StatusInternalServerError when an error occurs.
 })
@@ -139,6 +140,7 @@ r := render.New(render.Options{
     IsDevelopment: false,
     UseMutexLock: false,
     UnEscapeHTML: false,
+    HTMLTemplateOption: "",
     StreamingJSON: false,
     RequirePartials: false,
     DisableHTTPErrorRendering: false,

render.go

@@ -97,6 +97,8 @@ type Options struct {
 	UseMutexLock bool
 	// Unescape HTML characters "&<>" to their original values. Default is false.
 	UnEscapeHTML bool
+	// Sets the `Option` value for HTML templates. Defaults to blank ("").
+	HTMLTemplateOption string
 	// Streams JSON responses instead of marshalling prior to sending. Default is false.
 	StreamingJSON bool
 	// Require that all partials executed in the layout are implemented in all templates using the layout. Default is false.
@@ -217,6 +219,11 @@ func (r *Render) CompileTemplates() {
 func (r *Render) compileTemplatesFromDir() {
 	dir := r.opt.Directory
 	tmpTemplates := template.New(dir)
+
+	if len(r.opt.HTMLTemplateOption) > 0 {
+		tmpTemplates.Option(r.opt.HTMLTemplateOption)
+	}
+
 	tmpTemplates.Delims(r.opt.Delims.Left, r.opt.Delims.Right)
 
 	var watcher *fsnotify.Watcher
@@ -301,6 +308,11 @@ func (r *Render) compileTemplatesFromDir() {
 func (r *Render) compileTemplatesFromAsset() {
 	dir := r.opt.Directory
 	tmpTemplates := template.New(dir)
+
+	if len(r.opt.HTMLTemplateOption) > 0 {
+		tmpTemplates.Option(r.opt.HTMLTemplateOption)
+	}
+
 	tmpTemplates.Delims(r.opt.Delims.Left, r.opt.Delims.Right)
 
 	for _, path := range r.opt.AssetNames() {

render_html_test.go

@@ -6,6 +6,7 @@ import (
 	"html/template"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"testing"
 )
 
@@ -428,3 +429,75 @@ func TestHTMLDisabledCharset(t *testing.T) {
 	expect(t, res.Header().Get(ContentType), ContentHTML)
 	expect(t, res.Body.String(), "<h1>Hello gophers</h1>\n")
 }
+
+func TestHTMLTemplateOptionDefault(t *testing.T) {
+	render := New(Options{
+		Directory: "testdata/basic",
+	})
+
+	var err error
+
+	// Template expects "world" key.
+	templateData := map[string]int{"missing-key-here": 100}
+
+	h := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		err = render.HTML(w, http.StatusOK, "map", templateData)
+	})
+
+	res := httptest.NewRecorder()
+	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, "/foo", nil)
+	h.ServeHTTP(res, req)
+
+	expectNil(t, err)
+	expect(t, res.Code, 200)
+	expect(t, res.Header().Get(ContentType), ContentHTML+"; charset=UTF-8")
+	expect(t, res.Body.String(), "<h1>Hello </h1>\n")
+}
+
+func TestHTMLTemplateOptionZero(t *testing.T) {
+	render := New(Options{
+		Directory:          "testdata/basic",
+		HTMLTemplateOption: "missingkey=zero",
+	})
+
+	var err error
+
+	// Template expects "world" key.
+	templateData := map[string]int{"missing-key-here": 100}
+
+	h := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		err = render.HTML(w, http.StatusOK, "map", templateData)
+	})
+
+	res := httptest.NewRecorder()
+	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, "/foo", nil)
+	h.ServeHTTP(res, req)
+
+	expectNil(t, err)
+	expect(t, res.Code, 200)
+	expect(t, res.Header().Get(ContentType), ContentHTML+"; charset=UTF-8")
+	expect(t, res.Body.String(), "<h1>Hello 0</h1>\n")
+}
+
+func TestHTMLTemplateOptionError(t *testing.T) {
+	render := New(Options{
+		Directory:          "testdata/basic",
+		HTMLTemplateOption: "missingkey=error",
+	})
+
+	var err error
+
+	// Template expects "world" key.
+	templateData := map[string]string{"missing-key-here": "gophers"}
+
+	h := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		err = render.HTML(w, http.StatusOK, "map", templateData)
+	})
+
+	res := httptest.NewRecorder()
+	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, "/foo", nil)
+	h.ServeHTTP(res, req)
+
+	expectNotNil(t, err)
+	expect(t, strings.Contains(err.Error(), "map has no entry for key"), true)
+}

testdata/basic/map.tmpl

@@ -0,0 +1 @@
+<h1>Hello {{.world}}</h1>