udemy-go-web-1/pkg/render/render.go

package render

import (
	"fmt"
	"html/template"
	"log"
	"net/http"
)

var templateCache = make(map[string]*template.Template)

// RenderTemplate renders a HTML template file
func RenderTemplate(w http.ResponseWriter, t string) {
	var tmpl *template.Template
	var err error

	// Check if the template exists already in the cache map
	_, inMap := templateCache[t]
	if !inMap {
		// need to create the template
		log.Printf("Create template cache for the template %s\n", t)
		err = createTemplateCache(t)
		if err != nil {
			log.Println(err)
		}
	}
	tmpl = templateCache[t]

	// use the template
	err = tmpl.Execute(w, nil)
	if err != nil {
		log.Println(err)
	}
}

func createTemplateCache(t string) error {
	templates := []string{
		fmt.Sprintf("./templates/%s", t),
		"./templates/base.layout.tmpl",
	}

	// parse the template
	tmpl, err := template.ParseFiles(templates...)
	if err != err {
		return err
	}

	// add template to cache
	templateCache[t] = tmpl
	return nil
}