Using function instead of method in template - go

Question

I use the following code
var data struct {
File FZR
API API
}
const tmpl = `
{{- range .File.Modules}}
# in context of {{.Name}}
echo {{.EchoText}}
{{end}}`
func EchoText(m mts) string {
return m.Type
}
and like this its not working, now I change it to
func (m mts) EchoText() string {
return m.Type
}
it will work but I want to make it work with the first option, how can I do it ?
I mean update the template ...
update: as approva answer https://golang.org/pkg/text/template/#example_Template_func
but there is only string, how can I register the EchoText

Answer 1

As #mkopriva suggested in his first comment you just have to reference all your functions into a template.FuncMap where you establish the mapping from names to functions
Then into the template you just need to call them passing them the mts as parameter.
package main
import (
"log"
"os"
"text/template"
)
type mts struct {
Type1 string
Type2 string
}
func main() {
funcMap := template.FuncMap{
"myFunc1": EchoType1,
"myFunc2": EchoType2,
}
const templateText = `
Input: {{printf "%q" .}}
Output1:{{myFunc1 .}}
Output2:{{myFunc2 .}}
`
tmpl, err := template.New("myFuncTest").Funcs(funcMap).Parse(templateText)
if err != nil {
log.Fatalf("parsing: %s", err)
}
myMts := mts{Type1: "myType1", Type2: "myType2"}
err = tmpl.Execute(os.Stdout, myMts)
if err != nil {
log.Fatalf("execution: %s", err)
}
}
func EchoType1(m mts) string {
return m.Type1
}
func EchoType2(m mts) string {
return m.Type2
}
This will produce the following output :
Input: {"myType1" "myType2"}
Output1:myType1
Output2:myType2