Go funcMaps

This program demonstrates template.FuncMap in Go, which allows you to register custom functions and make them available inside templates. Here, two functions are registered: uc for uppercasing strings (using strings.ToUpper) and ft for extracting the first three characters. These can then be called directly in .gohtml template files using the or syntax.

package main

import (
	"os"
	// "io"
	"fmt"
	"log"
	"strings"
	"text/template"
)

var tpl *template.Template

func firstThree(s string) string  {
	s = strings.TrimSpace(s)
	s = s[:3]
	return s
}

var fm = template.FuncMap{
	"uc": strings.ToUpper,
	"ft": firstThree,
}

func init() {
	fmt.Println("Initializing ...")
	// tpl = template.Must(template.ParseGlob("*.gohtml"))
	//  to incorporate some extra function into template object
	tpl = template.Must(template.New("").Funcs(fm).ParseGlob("*.gohtml"))
}

type sage struct {
	Name  string
	Motto string
}

func main()  {
	b := sage{
		Name: "Buddha",
		Motto: "The belief of no beliefs",
	}

	g := sage{
		Name: "Gandhi",
		Motto: "Be the change",
	}

	j := sage{
		Name: "Jesus",
		Motto: "Love!",
	}

	sages := []sage{b, g, j}

	data := struct{
		Wisdom []sage
	}{
		Wisdom: sages,
	}

	err := tpl.ExecuteTemplate(os.Stdout, "funcintpl.gohtml", data)
	if err != nil {
		log.Fatalln(err)
	}


}