vendor/gopkg.in/go-playground/validator.v9/_examples/custom/main.go

   1 package main
   2
   3 import (
   4         "database/sql"
   5         "database/sql/driver"
   6         "fmt"
   7         "reflect"
   8
   9         "gopkg.in/go-playground/validator.v9"
  10 )
  11
  12 // DbBackedUser User struct
  13 type DbBackedUser struct {
  14         Name sql.NullString `validate:"required"`
  15         Age  sql.NullInt64  `validate:"required"`
  16 }
  17
  18 // use a single instance of Validate, it caches struct info
  19 var validate *validator.Validate
  20
  21 func main() {
  22
  23         validate = validator.New()
  24
  25         // register all sql.Null* types to use the ValidateValuer CustomTypeFunc
  26         validate.RegisterCustomTypeFunc(ValidateValuer, sql.NullString{}, sql.NullInt64{}, sql.NullBool{}, sql.NullFloat64{})
  27
  28         // build object for validation
  29         x := DbBackedUser{Name: sql.NullString{String: "", Valid: true}, Age: sql.NullInt64{Int64: 0, Valid: false}}
  30
  31         err := validate.Struct(x)
  32
  33         if err != nil {
  34                 fmt.Printf("Err(s):\n%+v\n", err)
  35         }
  36 }
  37
  38 // ValidateValuer implements validator.CustomTypeFunc
  39 func ValidateValuer(field reflect.Value) interface{} {
  40
  41         if valuer, ok := field.Interface().(driver.Valuer); ok {
  42
  43                 val, err := valuer.Value()
  44                 if err == nil {
  45                         return val
  46                 }
  47                 // handle the error how you want
  48         }
  49
  50         return nil
  51 }