/validating-go

A Go library for validating structs, maps and slices.

Primary LanguageGoMIT LicenseMIT

validating

A Go library for validating structs, maps and slices.

Features

  1. Simple

    Simple and stupid, no magic involved.

  2. Type-safe

    Schema is defined in Go, which is type-safer (and more powerful) than traditional struct tags.

  3. Flexible

    • Validators are composable.
    • Nested struct validation is well supported.
    • Schema can be defined inside or outside struct.
    • Validator customizations are made easy.

  4. No reflection

Installation

$ go get github.com/RussellLuo/validating/v3@latest

Quick Start

package main

import (
	"fmt"

	v "github.com/RussellLuo/validating/v3"
)

type Address struct {
	Country string
	City    string
}

func (a Address) Schema() v.Schema {
	return v.Schema{
		v.F("country", a.Country): v.Nonzero[string]().Msg("empty country"),
		v.F("city", a.City):       v.In("A", "B", "C").Msg("must be A or B or C"),
	}
}

type Person struct {
	Name    string
	Age     int
	Hobbies []string
	Address Address
}

func (p Person) Schema() v.Schema {
	return v.Schema{
		v.F("name", p.Name): v.All(
			v.LenString(5, 10).Msg("bad name length"),
			v.Match(`\w+`).Msg("bad name pattern"),
		),
		v.F("age", p.Age):         v.Gte(10).Msg("must be at least 10 years old"),
		v.F("hobbies", p.Hobbies): v.EachSlice[[]string](v.In("Reading", "Sports", "Music").Msg("unknown hobby")),
		v.F("address", p.Address): p.Address.Schema(),
	}
}

func main() {
	p := Person{
		Name:    "Foo",
		Age:     5,
		Hobbies: []string{"Nothing"},
		Address: Address{City: "D"},
	}
	errs := v.Validate(p.Schema())
	for _, err := range errs {
		fmt.Println(err)
	}
}
$ go run main.go
name: INVALID(bad name length)
age: INVALID(must be at least 10 years old)
hobbies[0]: INVALID(unknown hobby)
address.country: INVALID(empty country)
address.city: INVALID(must be A or B or C)

Validator factories and validators

To be strict, this library has a conceptual distinction between validator factory and validator.

A validator factory is a function used to create a validator, which will do the actual validation.

Built-in validator factories

Extension validator factories

Validator customizations

Examples

Documentation

Check out the Godoc.

Thanks

This library borrows some ideas from the following libraries:

License

MIT