Joi noChange Plugin

A Joi plugin that validates the field it is attached to matches a sister object at the same path. This is extremely helpful when validating JSON Patches.

Installing

npm install joi-nochange --save

v3 Breaking Changes

Instead of having joi-nochange extend Joi when required, v3 allows an instance of Joi to be passed in. This fixes an issue where other uses of Joi.extend would become innefective if used before requiring joi-nochange.

To migrate, change

const Joi = require('joi-nochange');

to

const Joi = require('joi-nochange')(require('joi'));

Usage

const Joi = require('joi-nochange')(require('joi'));

const origObj = {
    id: 'k1773y',
    name: 'Cuddles',
    favoriteToys: ['string'],
    meta: {
        born: 1452474481612,
        weight: 2.1 // pounds
    }
};

const kitty = JSON.parse(JSON.stringify(origObj)); // clone

kitty.meta.weight += 10; // Cuddles has been eating a lot
kitty.favoriteToys.push('catnip'); // and also likes catnip
kitty.id = 'best-cat-ever'; // but really isn't allowed to change ids

const schema = Joi.object().keys({
    id: Joi.string().noChange(origObj).required().label('id'),
    name: Joi.string().required().label('name'),
    favoriteToys: Joi.array().items(Joi.string().label('toy')).default([]).label('favoriteToys'),
    meta: {
        born: Joi.number().positive().integer().noChange(origObj).required().label('born'),
        weight: Joi.number().positive().unit('pounds').label('weight')
    }
}).label('cat');

const result = schema.validate(kitty);
// check and throw if there is an error (there is)
if (result.error) {
    throw result.error; // Joi Error: "child "cat" fails because ["id" is not allowed to change]"
}
// object is available at `result.value`

Compatible Joi versions

This plugin works with multiple versions of Joi. Compatibility chart:

joi version	joi-nochange version
< 9.0.0	< 1.0.0 (joi-pre-v9 branch)
9.0.0 - 10.2.2	1.x.x (joi-v9 branch)
10.x.x	2.x.x (joi-v10 branch)
11.0.0 +	> 3.0.0 (master branch)

Finding Compatible Versions

There is a find-compatible.js script that tests the currently checked out branch of joi-nochange against all versions of joi>6.