Custom template functions not found in html template

Question

I render templates this way:

  func renderTemplate(...........) {
    rt := template.Must(template.ParseFiles(
        fmt.Sprintf("%s/%s", templatesPath, baseLayoutPath),
        fmt.Sprintf("%s/%s", templatesPath, tplName)))

      err := rt.ExecuteTemplate(w, "base", nil)
      //[................]
  }

I want to register a custom function in it:

func myTest1(string s) string {
  return "hello: " + s
}


func renderTemplate(...........) {
  rt := template.Must(template.ParseFiles(
              fmt.Sprintf("%s/%s", templatesPath, baseLayoutPath),
              fmt.Sprintf("%s/%s", templatesPath, tplName))).Funcs(template.FuncMap{"test1": myTest1})

This doesn't work: "test1" not defined"

  // html template:


  {{range .items}}

    {{.Field1 | test1}}

Why not and how to make it work?

blobdon · Answer 1 · 2018-12-29T18:28:45.623

Add the template functions before you parse the templates.

From the html/template docs for Funcs():

Funcs adds the elements of the argument map to the template's function map. It must be called before the template is parsed.

funcMap := template.FuncMap{"test1":myTest1}
rt := template.Must(template.New("name").Funcs(funcMap).ParseFiles(
          fmt.Sprintf("%s/%s", templatesPath, baseLayoutPath),
          fmt.Sprintf("%s/%s", templatesPath, tplName)))

Custom template functions not found in html template

1 Answers1