validation.go

func (c *TagsAPIController) List(w http.ResponseWriter, r *http.Request, params map[string]string) (interface{}, error) {
  val := NewValidator()
	val.Param("limit").IsInt().Default("1000").Max(1000).Min(0)
	val.Param("resolution").Allowed([]string{"month", "day", "year"})
	val.Param("page").Allowed([]string{"first", "last", "next", "prev"}).Default("first")
	val.Param("prefix")
	val.Param("tag")
	params, err := val.Validate(r)
	if err != nil {
		return nil, err
	}
	
	limit := params.Int("limit")

	if params.Set("prefix") {
		// Do something
	}