kensho

Kenshō - A Go validator

A Work in progress project so the master branch might change in the future and BC breaks some part or change some behaviors.

A simple Go library for validation, but gives the possibility to validate deeply, collections, any field type of struct by following tag or file.

TODO

• More docs/examples
• More tests
• Add validators

Features

• Struct validation
• Able to add custom constraints
• Validator argument
• Configuration from a file (ex: json)
• Deep validation
• List of struct validation
• Translation

Installation

go get github.com/maxperrimond/kensho

Usage

Here some code as an example:

package main

import (
	"fmt"

	"github.com/maxperrimond/kensho"
)

type Group struct {
	Name  string  `valid:"required"`
	Users []*User `valid:"valid"` // Ask to valid users if there is some
}

type User struct {
	Email     string `valid:"required,email"`
	FirstName string `valid:"required,min=2,max=64"`
	LastName  string `valid:"required,min=2,max=64"`
}

func main() {
	// Simple struct
	user := &User{
		Email:     "foo.bar@example.com",
		FirstName: "foo",
		LastName:  "bar",
	}

	// Validate user
	ok, violations, _ := kensho.Validate(user)

	fmt.Printf("Result: %t\n", ok)
	fmt.Println(violations)

	user.Email = "this is not an email"
	user.FirstName = ""

	// Validate user after inserting bad data
	ok, violations, _ = kensho.Validate(user)

	fmt.Printf("Result: %t\n", ok)
	fmt.Println(violations)

	users := []*User{
		{
			Email:     "john@example.com",
			FirstName: "john",
			LastName:  "bar",
		},
		{
			Email:     "pierre@example.com",
			FirstName: "pierre",
			LastName:  "bar",
		},
	}

	// Validate collection of users
	ok, violations, _ = kensho.Validate(users)

	fmt.Printf("Result: %t\n", ok)
	fmt.Println(violations)

	// Nested struct
	group := &Group{
		Name:  "foo",
		Users: append(users, user), // With the bad user
	}

	// Validate the group
	ok, violations, _ = kensho.Validate(group)

	fmt.Printf("Result: %t\n", ok)
	fmt.Println(violations)
}

Available constraints

And more to come

Custom constraint

package main

import (
	"context"
	"errors"

	"github.com/maxperrimond/kensho"
)

// Define your constraint
func poneyConstraint(ctx *kensho.ValidationContext) error {
	if ctx.Value() != "poney" {
		ctx.BuildViolation("invalid_poney", nil).AddViolation()
	}

	return nil
}

func init() {
	// add it with the tag of your choice
    kensho.AddConstraint("poney", poneyConstraint)
}

Note: If you use an existent tag, it will override it.

Context

You can pass a context during validation so it can be accessible in constraints:

ok, violations, err := kensho.ValidateWithContext(ctx, subject)