Check for invalid templates at server startup

main.go

@@ -2,42 +2,26 @@ package main
 
 import (
 	"fmt"
-	"html/template"
-	"log"
 	"net/http"
 	"path/filepath"
+	"strings"
 
 	"github.com/go-chi/chi/v5"
 	"github.com/go-chi/chi/v5/middleware"
+
+	"git.kealoha.me/lks/lenslocked/views"
 )
 
-func executeTemplate(w http.ResponseWriter, filepath string) {
-	w.Header().Set("Content-Type", "text/html; charset=utf8")
-	tpl, err := template.ParseFiles(filepath)
+func addStaticTemplate(r chi.Router, pattern string, filepath string) {
+	tpl := views.Must(views.FromFile(filepath))
+
+	var testWriter strings.Builder
+	err := tpl.ExecuteWriter(&testWriter, nil)
 	if err != nil {
-		log.Printf("Error parsing template: %v", err)
-		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
-		return
-	}
-	err = tpl.Execute(w, nil)
-	if err != nil {
-		log.Printf("Error executing template: %v", err)
-		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
-		return
-	}
+		panic(err)
 	}
 
-func homeHandler(w http.ResponseWriter, r *http.Request) {
-	path := filepath.Join("templates", "home.gohtml")
-	executeTemplate(w, path)
-}
-func contactHandler(w http.ResponseWriter, r *http.Request) {
-	path := filepath.Join("templates", "contact.gohtml")
-	executeTemplate(w, path)
-}
-func faqHandler(w http.ResponseWriter, r *http.Request) {
-	path := filepath.Join("templates", "faq.gohtml")
-	executeTemplate(w, path)
+	r.Get(pattern, func(w http.ResponseWriter, r *http.Request) { tpl.Execute(w, nil) })
 }
 
 func notFoundHandler(w http.ResponseWriter, r *http.Request) {
@@ -49,9 +33,9 @@ func notFoundHandler(w http.ResponseWriter, r *http.Request) {
 func main() {
 	r := chi.NewRouter()
 	r.Use(middleware.Logger)
-	r.Get("/", homeHandler)
-	r.Get("/contact", contactHandler)
-	r.Get("/faq", faqHandler)
+	addStaticTemplate(r, "/", filepath.Join("templates", "home.gohtml"))
+	addStaticTemplate(r, "/contact", filepath.Join("templates", "contact.gohtml"))
+	addStaticTemplate(r, "/faq", filepath.Join("templates", "faq.gohtml"))
 	r.NotFound(notFoundHandler)
 	fmt.Println("Starting the server on :3000...")
 	http.ListenAndServe(":3000", r)

views/template.go

@@ -0,0 +1,43 @@
+package views
+
+import (
+	"fmt"
+	"html/template"
+	"io"
+	"log"
+	"net/http"
+)
+
+type Template struct {
+	htmlTpl *template.Template
+}
+
+func (t Template) Execute(w http.ResponseWriter, data interface{}) {
+	w.Header().Set("Content-Type", "text/html; charset=utf8")
+	err := t.htmlTpl.Execute(w, data)
+	if err != nil {
+		log.Printf("Error executing template: %v", err)
+		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+		return
+	}
+}
+func (t Template) ExecuteWriter(w io.Writer, data interface{}) error {
+	return t.htmlTpl.Execute(w, data)
+}
+
+func FromFile(filepath string) (Template, error) {
+	tpl, err := template.ParseFiles(filepath)
+	if err != nil {
+		return Template{}, fmt.Errorf("Error parsing template: %v", err)
+	}
+	return Template{
+		htmlTpl: tpl,
+	}, nil
+}
+
+func Must(t Template, err error) Template {
+	if err != nil {
+		panic(err)
+	}
+	return t
+}