cospectrum/validol

Validation library for golang

validol

Validation library for golang.

Content

• Install
• Usage
• Validators
• Combinators

Install

go get -u github.com/cospectrum/validol

Requires Go version 1.22.0 or greater.

Usage

import (
	"errors"
	vd "github.com/cospectrum/validol"
)

type Sex string

func (s Sex) Validate() error {
	return vd.OneOf[Sex]("male", "female", "other")(s)
}

type Email string

func (e Email) Validate() error {
	return vd.All(
		vd.Len[string](vd.Gt(5)),
		vd.Len[string](vd.Lte(100)),
		vd.Email,
	)(string(e))
}

type User struct {
	Email Email
	Sex   Sex
	age   int
}

func (u User) Validate() error {
	return errors.Join(
		vd.Gte(18)(u.age),
		vd.Walk(u), // to continue the `Walk` using the descendants' `Validate` methods
	)
}

func main() {
	users := []User{
		{Email: "first_user@mail.com", age: 22},
		{Email: "second_user@mail.com", Sex: "male"},
	}
	if err := vd.Validate(users); err != nil {
		panic(err)
	}
}

Validators

Type Validator[T] is equivalent to func(T) error.
Validatable interface requires Validate() error method.

Name	Input	Description
Validate	T	If T is Validatable, then it will call Validate method, otherwise will call Walk
Walk	T	Recursively calls Validate method for descendants of T. The descendants of the Validatable descendant will not be checked automatically, instead the type must continue Walk manually (inside its own Validate). The descendants are public struct fields, embedded types, slice/array elements, map keys/values.
Required	T	Checks that the value is different from default
Empty	T	Checks that the value is initialized as default
NotNil	T	Checks that the value is different from nil
Nil	T	Checks that the value is nil
True	bool	Checks that the value is true
False	bool	Checks that the value is false
Email	string	Email string
UUID4	string	Universally Unique Identifier UUID v4

Combinators

Functions that create a Validator[T].

Name	Input	Output	Description
All	...Validator[T]	Validator[T]	Checks whether all validations have been completed successfully
Any	...Validator[T]	Validator[T]	Checks that at least one validation has been completed successfully
Not	Validator[T]	Validator[T]	Logical not
And	Validator[T], Validator[T]	Validator[T]	Checks that both validations have been completed successfully
Or	Validator[T], Validator[T]	Validator[T]	Checks the success of one of the two validations
OneOf	...T	Validator[T]	Checks that the value is equal to one of the specified
Eq	T comparable	Validator[T]	==
Ne	T comparable	Validator[T]	!=
Gt	T cmp.Ordered	Validator[T]	>
Gte	T cmp.Ordered	Validator[T]	>=
Lt	T cmp.Ordered	Validator[T]	<
Lte	T cmp.Ordered	Validator[T]	<=
Len	Validator[int]	Validator[T]	Checks whether the len of the object passes the specified Validator[int]
StartsWith	string	Validator[string]	Checks if the string starts with the specified prefix
EndsWith	string	Validator[string]	Checks whether the string ends with the specified suffix
Contains	string	Validator[string]	Checks whether the specified substr is within string
ContainsRune	rune	Validator[string]	Checks whether the specified Unicode code point is within string