Golang : How to call function inside template with template.FuncMap
Alright, just a simple tutorial on how to call your own function inside HTML template. For this example, we will "import" the WordWrap function into the template using the template.FuncMap()
and call it from inside a template.
Here you go!
package main
import (
"fmt"
"os"
"strings"
"text/template"
)
const TextData = `After wordwrap :
{{(wordwrap .Message 3) }}` // change 3 to 2 or 1 and see how it goes
var templateDataMap = map[string]interface{}{}
func main() {
templateDataMap["Message"] = "this is a simple message string"
var ownFuncs = template.FuncMap{"wordwrap": WordWrap}
var PageBody = template.Must(template.New("PageBody").Funcs(ownFuncs).Parse(TextData))
if err := PageBody.ExecuteTemplate(os.Stdout, "PageBody", templateDataMap); err != nil { // replace os.Stdout with w http.ResponseWriter for html/template
fmt.Println(err)
}
}
func WordWrap(s string, limit int) string {
if strings.TrimSpace(s) == "" {
return s
}
// convert string to slice
strSlice := strings.Fields(s)
var result string = ""
for len(strSlice) >= 1 {
// convert slice/array back to string
// but insert \r\n at specified limit
result = result + strings.Join(strSlice[:limit], " ") + "\r\n"
//result = result + strings.Join(strSlice[:limit], " ") + "<br>" this is for HTML
// discard the elements that were copied over to result
strSlice = strSlice[limit:]
// change the limit
// to cater for the last few words in
//
if len(strSlice) < limit {
limit = len(strSlice)
}
}
return result
}
Sample output:
this is
a simple
message string
References:
https://www.socketloop.com/references/golang-html-template-funcmap-type-examples
https://www.socketloop.com/tutorials/golang-populate-dropdown-with-html-template-example
See also : Golang : Auto-generate reply email with text/template package
By Adam Ng
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