add vendor

vendor/gopkg.in/go-playground/validator.v8/examples/custom/custom.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"database/sql"
+	"database/sql/driver"
+	"fmt"
+	"reflect"
+
+	"gopkg.in/go-playground/validator.v8"
+)
+
+// DbBackedUser User struct
+type DbBackedUser struct {
+	Name sql.NullString `validate:"required"`
+	Age  sql.NullInt64  `validate:"required"`
+}
+
+func main() {
+
+	config := &validator.Config{TagName: "validate"}
+
+	validate := validator.New(config)
+
+	// register all sql.Null* types to use the ValidateValuer CustomTypeFunc
+	validate.RegisterCustomTypeFunc(ValidateValuer, sql.NullString{}, sql.NullInt64{}, sql.NullBool{}, sql.NullFloat64{})
+
+	x := DbBackedUser{Name: sql.NullString{String: "", Valid: true}, Age: sql.NullInt64{Int64: 0, Valid: false}}
+	errs := validate.Struct(x)
+
+	if errs != nil {
+		fmt.Printf("Errs:\n%+v\n", errs)
+	}
+}
+
+// ValidateValuer implements validator.CustomTypeFunc
+func ValidateValuer(field reflect.Value) interface{} {
+	if valuer, ok := field.Interface().(driver.Valuer); ok {
+		val, err := valuer.Value()
+		if err == nil {
+			return val
+		}
+		// handle the error how you want
+	}
+	return nil
+}