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
	Address Address
}

func (p Person) Schema() v.Schema {
	return v.Schema{
		v.F("name", p.Name):       v.LenString(1, 5).Msg("bad name"),
		v.F("age", p.Age):         v.Gte(10).Msg("must be older than 10 years old"),
		v.F("address", p.Address): p.Address.Schema(),
	}
}

func main() {
	p := Person{}
	errs := v.Validate(p.Schema())
	for _, err := range errs {
		fmt.Println(err)
	}
}

$ go run main.go
name: INVALID(bad name)
age: INVALID(must be older than 10 years old)
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

• Func
• Schema
• Value
• Nested
• EachMap
• EachSlice
• Map
• Slice/Array
• All/And
• Any/Or
• Not
• Is
• Nonzero
• Zero
• ZeroOr
• LenString
• LenSlice
• RuneCount
• Eq
• Ne
• Gt
• Gte
• Lt
• Lte
• Range
• In
• Nin
• Match

Extension validator factories

• vext

Validator customizations

• From a boolean function
• From a normal function
• From a struct

Examples

• Simple value
• Simple string (is IP?)
• Simple struct
• Simple slice
• Simple map
• Nested struct
• Nested struct (schema inside)
• Nested struct pointer
• Nested struct slice
• Nested struct map

Documentation

Check out the Godoc.

Thanks

This library borrows some ideas from the following libraries:

• mholt/binding

  Prefer no reflection.

• alecthomas/voluptuous

  Support composite validator factories All/And, Any/Or.

• go-validator/validator

  Use the term nonzero instead of required/optional.

License

MIT