required.go

// Copyright 2016 Qiang Xue. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package validation

import "errors"

// Required is a validation rule that checks if a value is not empty.
// A value is considered not empty if
// - integer, float: not zero
// - bool: true
// - string, array, slice, map: len() > 0
// - interface, pointer: not nil and the referenced value is not empty
// - any other types
var Required = &requiredRule{message: "cannot be blank", skipNil: false}

// NilOrNotEmpty checks if a value is a nil pointer or a value that is not empty.
// NilOrNotEmpty differs from Required in that it treats a nil pointer as valid.
var NilOrNotEmpty = &requiredRule{message: "cannot be blank", skipNil: true}

type requiredRule struct {
	message string
	skipNil bool
}

// Validate checks if the given value is valid or not.
func (v *requiredRule) Validate(value interface{}) error {
	value, isNil := Indirect(value)
	if v.skipNil && !isNil && IsEmpty(value) || !v.skipNil && (isNil || IsEmpty(value)) {
		return errors.New(v.message)
	}
	return nil
}

// Error sets the error message for the rule.
func (v *requiredRule) Error(message string) *requiredRule {
	return &requiredRule{
		message: message,
		skipNil: v.skipNil,
	}
}