从模板执行中获取值

Question

I have a HTML template that I execute passing a map[string]string variable. The template uses the variable to create the HTML output that I send to clients.

In addition to producing the HTML, I would like to use the very same template to generate some values that are retured to the main program, so I can use the same file to put some logic externally.

As far as I know, it is not possible to modify the variable I pass to Execute (something like {{.output = "value"}}).

So how could I get multiple output values from a template Execution?

Answer 1

You don't actually need to pass a funcmap, just pass the struct.

var tmpl = template.Must(template.New("test").Parse(`Before: {{.Data}}{{.Set "YY"}}, after: {{.Data}}`))

func main() {
    c := &CustomData{"XX"}
    tmpl.Execute(os.Stdout, c)
    fmt.Println()
}

<kbd>playground</kbd>

You can always pass a FuncMap to the template, here's an extremely simple example:

const tmpl = `Before: {{.Data}}{{.Set "YY"}}, after: {{.Data}}`

type CustomData struct {
    Data string
}

func (c *CustomData) Set(d string) string { // it has to return anything
    c.Data = d
    return ""
}

func main() {
    c := &CustomData{"XX"}
    funcMap := template.FuncMap{
        "Set": c.Set,
    }
    t, _ := template.New("test").Funcs(funcMap).Parse(tmpl) // don't ignore errors in real code
    t.Execute(os.Stdout, c)
    fmt.Println()
}

<kbd>playground</kbd>