Quick and dirty example of HTML forms with validation dropping data into a struct. Note that the scanf should probably be replaced with a type switch, because it likes tokenized input.

formtpl.go

package main

import (
	"fmt"
	"html/template"
	"net/url"
	"os"
	"regexp"
)

type FormElement interface {
	HTML() template.HTML
	Validate(url.Values) error
}

type TextInput struct {
	ID     string
	Output interface{}
	Valid  *regexp.Regexp
}

func (t *TextInput) HTML() template.HTML {
	form := fmt.Sprintf(`<input type=%q id=%q name=%q />`, "text", t.ID, t.ID)
	return template.HTML(form)
}

func (t *TextInput) Validate(form url.Values) error {
	val := form.Get(t.ID)
	if !t.Valid.MatchString(val) {
		return fmt.Errorf("%q does not match /%s/", val, t.Valid)
	}
	if len(val) == 0 {
		return nil
	}
	if _, err := fmt.Sscan(val, t.Output); err != nil {
		return fmt.Errorf("%q cannot be stored in %T: %s", val, t.Output, err)
	}
	return nil
}

type Address struct {
	Name        string
	Street      [2]string
	City, State string
	Zip         int
}

func (a *Address) Form() map[string]FormElement {
	return map[string]FormElement{
		"name":    &TextInput{"nm", &a.Name, regexp.MustCompile(`\S+\s+\S+`)},
		"street1": &TextInput{"sn", &a.Street[0], regexp.MustCompile(`\d+.*\S+`)},
		"street2": &TextInput{"sx", &a.Street[1], regexp.MustCompile(`|\S+`)},
		"city":    &TextInput{"ct", &a.City, regexp.MustCompile(`\S+`)},
		"state":   &TextInput{"st", &a.State, regexp.MustCompile(`\S{2}`)},
		"zip":     &TextInput{"zp", &a.Zip, regexp.MustCompile(`\d{5}(-\d{4})?`)},
	}
}

func main() {
	var a Address
	form := a.Form()

	tpl := template.Must(template.New("").Parse("{{.name.HTML}}\n{{.street1.HTML}}\n...\n\n"))
	tpl.Execute(os.Stdout, form)

	reply := url.Values{
		"nm": {"Zaphod Beeblebrox"},
		"sn": {"42 Heart of Gold"},
		"ct": {"Betelgeuse Central"},
		"st": {"BG"},
		"zp": {"42069"},
	}
	for id, f := range form {
		if err := f.Validate(reply); err != nil {
			fmt.Printf("%q - %s\n", id, err)
		}
	}
	fmt.Printf("%#v", a)
}