func (f Values) PostError() error {
	msg := f.Get(PostResultKey)
	if msg == "" {
		return nil
	}
	return errors.New(msg)
}
PostError get the post result.
package form
import (
	"errors"
)
const (
	PostTypeKey           = "__go_admin_post_type"
	PostResultKey         = "__go_admin_post_result"
	PostIsSingleUpdateKey = "__go_admin_is_single_update"
	PreviousKey = "__go_admin_previous_"
	TokenKey    = "__go_admin_t_"
	MethodKey   = "__go_admin_method_"
	NoAnimationKey = "__go_admin_no_animation_"
)
type Values map[string][]string
func (f Values) Get(key string) string {
	if len(f[key]) > 0 {
		return f[key][0]
	}
	return ""
}
func (f Values) Add(key string, value string) {
	f[key] = []string{value}
}
func (f Values) IsEmpty(key ...string) bool {
	for _, k := range key {
		if f.Get(k) == "" {
			return true
		}
	}
	return false
}
func (f Values) Has(key ...string) bool {
	for _, k := range key {
		if f.Get(k) != "" {
			return true
		}
	}
	return false
}
func (f Values) Delete(key string) {
	delete(f, key)
}
func (f Values) ToMap() map[string]string {
	var m = make(map[string]string)
	for key, v := range f {
		if len(v) > 0 {
			m[key] = v[0]
		}
	}
	return m
}
func (f Values) IsUpdatePost() bool {
	return f.Get(PostTypeKey) == "0"
}
func (f Values) IsInsertPost() bool {
	return f.Get(PostTypeKey) == "1"
}