template-inheritance.go

package main

import (
	"bytes"
	"errors"
	"html/template"
	"net/http"
	"path/filepath"
)

type Render struct {
	Templates map[string]*template.Template
}

func NewRender(layoutPath string, includePath string) (*Render, error) {
	r := &Render{Templates: make(map[string]*template.Template)}

	layoutFiles, err := filepath.Glob(layoutPath + "*.html")
	if err != nil {
		return nil, err
	}

	includeFiles, err := filepath.Glob(includePath + "*.html")
	if err != nil {
		return nil, err
	}

	mainTmpl := `{{define "main" }} {{ template "base" . }} {{ end }}`
	mainTemplate := template.Must(template.New("main").Parse(mainTmpl))
	for _, file := range includeFiles {
		fileName := filepath.Base(file)
		files := append(layoutFiles, file)
		r.Templates[fileName], err = mainTemplate.Clone()
		if err != nil {
			return nil, err
		}
		r.Templates[fileName] = template.Must(r.Templates[fileName].ParseFiles(files...))
	}

	return r, nil
}

func (r *Render) Render(name string, data interface{}) ([]byte, error) {
	tmpl, ok := r.Templates[name]
	if !ok {
		return nil, errors.New("cant find template")
	}

	buf := &bytes.Buffer{}

	err := tmpl.Execute(buf, data)
	return buf.Bytes(), err
}

func main() {
	r, _ := NewRender("views/layout/", "views/")

	mux := http.NewServeMux()
	mux.HandleFunc("/1", func(w http.ResponseWriter, req *http.Request) {
		data, _ := r.Render("index.html", nil)
		w.Write(data)
	})
	mux.HandleFunc("/2", func(w http.ResponseWriter, req *http.Request) {
		data, _ := r.Render("post.html", nil)
		w.Write(data)
	})

	(&http.Server{
		Handler: mux,
		Addr:    ":3000",
	}).ListenAndServe()
}