hvalid

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hvalid is a lightweight validation library written in Go. It defines a rule type and ships common rules, so you can check data quickly.

Features

• Generics. Check numbers, text, slices, maps, times, and defined types such as type Age int. A struct is checked by a rule you write for that struct.
• Small call. Pass the field name once to Validate, then pass the rules. A rule does not carry the field name.
• Extensible. A custom rule has the same type as a built-in rule, so both can be passed to Validate.
• Clear errors. Failure returns one error. It names the field and lists every reason.

A failed check looks like this:

name: value length too short
count: must be greater than or equal to 1; must be less than or equal to 10

Install

go get github.com/lyonnee/hvalid

Check one value

import "github.com/lyonnee/hvalid"

err := hvalid.Validate("name", "hi", hvalid.MinLen[string](3))
// name: value length too short

err = hvalid.Validate("count", 10, hvalid.Min(5), hvalid.Max(15))

Validate runs every rule. Reasons are joined with "; ". A direct call such as hvalid.Min(5)(4) returns only must be greater than or equal to 5, because no field name was given.

Defined types use the same rules:

type Age int

err := hvalid.Validate("age", Age(17), hvalid.Min[Age](18))

Check a struct

Write a rule for the struct and call Validate once per field. Return that error as-is so the field name stays intact.

type User struct {
	Name string
	Age  int
}

func UserRule() hvalid.ValidatorFunc[User] {
	return func(user User) error {
		if err := hvalid.Validate("name", user.Name, hvalid.MinLen[string](1)); err != nil {
			return err
		}
		return hvalid.Validate("age", user.Age, hvalid.Min(18))
	}
}

err := UserRule()(User{Name: "Zhang San", Age: 20})

Custom rules

A custom rule is the same type as a built-in one. Its error text becomes one reason.

import "errors"

func IsPositive() hvalid.ValidatorFunc[int] {
	return func(n int) error {
		if n <= 0 {
			return errors.New("must be positive")
		}
		return nil
	}
}

err := hvalid.Validate("n", 0, IsPositive())
// n: must be positive

Rules

Rule	Value
Min, Max, Range, Positive, Negative	numbers, including defined numeric types
MinLen, MaxLen	string, []byte, and defined text types
MinItems, MaxItems, NotEmpty, Empty, Contains	slices
MinSize, MaxSize, MapNotEmpty, MapEmpty, HasKey, NoKey	maps
IsTrue, IsFalse	bool
Before, After, Equal, Between	time.Time
ContainsStr, Regexp	string
ContainsBytes	[]byte
Eq	any value

MinLen is for text. Slice length is MinItems.

Email, IPv4, IPv6, and URL checks live in validators/primitive and already include a field name, so call them directly:

import "github.com/lyonnee/hvalid/validators/primitive"

err := primitive.NewStringValidator("email").IsEmail()("user@example.com")

Test

go test ./...

License

MIT. See LICENSE.