Go, Template, Helper Rendering

cmd_web_handlers.go

func snippetViewHandler(app *application) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		id, err := strconv.Atoi(r.PathValue("id"))

		if err != nil || id < 1 {
			app.clientError(w, http.StatusNotFound)
			return
		}

		s, err := app.snippets.Get(id)
		if err != nil {
			if errors.Is(err, models.ErrNoRecord) {
				app.clientError(w, http.StatusNotFound)
				return
			} else {
				app.serverError(w, r, err)
				return
			}
		}

		app.render(w, r, 200, "view.tmpl", templateData{Snippet: s})
	}
}

cmd_web_helpers.go

func (app *application) render(w http.ResponseWriter, r *http.Request, status int, page string, data templateData) {
	ts, ok := app.templateCache[page]
	if !ok {
		app.serverError(w, r, fmt.Errorf("the template %s does not exist", page))
	}

	buf := new(bytes.Buffer)

	err := ts.ExecuteTemplate(buf, "base", data)
	if err != nil {
		app.serverError(w, r, err)
		return
	}

	w.WriteHeader(status)
	buf.WriteTo(w)
}

cmd_web_main.go

func main() {
  // ...
  templateCache, err := newTemplateCache()
	if err != nil {
		logger.Error(err.Error())
		os.Exit(1)
	}

	app := &application{
		logger:        logger,
		snippets:      &models.SnippetModel{DB: db},
		templateCache: templateCache,
	}
  // ...
}

cmd_web_templates.go

func newTemplateCache() (map[string]*template.Template, error) {
	cache := map[string]*template.Template{}

	pages, err := filepath.Glob("./ui/html/pages/*.tmpl")
	if err != nil {
		return nil, err
	}

	for _, page := range pages {
		name := filepath.Base(page)

		ts, err := template.ParseFiles("./ui/html/base.tmpl")
		if err != nil {
			return nil, err
		}

		ts, err = ts.ParseGlob("./ui/html/partials/*.tmpl")
		if err != nil {
			return nil, err
		}

		ts, err = ts.ParseFiles(page)
		if err != nil {
			return nil, err
		}

		cache[name] = ts
	}

	return cache, nil
}