douglaseggleton / golden-validator

The easy peasy validation library

THIS LIBRARY IS STILL IN DEVELOPMENT AND IN ALPHA. THIS IS A GREAT TIME TO GET INVOLVED WITH CONTRIBUTING TO THIS LIBRARY. ALTHOUGH IT WORKS, USE IT AT YOUR OWN RISK.

Golden Validator

The easy peasy validation library!

Validation is not new and generally present as a feature of a larger framework. With that, the objective of this library is to have a standalone validation tool that can be used anywhere Javascript is used. It is heavily inspired by the functional programming paradigm and even supports Typescript.

Installation

If you use yarn

yarn add golden-validator

If you use npm

npm install golden-validator 

Basic Usage

import { isGreaterThan, createSchema, createRule, isValid } from 'golden-validator';
const user: User = {
    age: 50
};

const userSchema = createSchema<User>({
    age: createRule({
        required: true,
        validators: [
            isGreaterThan(18),
            ...
        ]
    })
});

isValid<User>(user, userSchema) // boolean

Custom Usage

It is easy to write your own validators if you believe the required functionality is not part of this library. For example, let's write a custom validator to check whether or not a substring is included in a string.

const hasSubstring: ValidatorFactory = substring => ({
    evaluator: value => value.includes(substring);
    errorMessage: `does not contain ${substring}`;
})

// then you can use it in a schema as such
const userSchema = createSchema<User>({
    email: createRule({
        required: true
        validators: [
            hasSubstring('@'),
            ...
        ]
    }):

})

You can then use the custom validator and include it in the validators array as seen in the example above. To decouple and easily test your code further, you can use a utility function to create your validators.

import { createValidatorFactory } from 'golden-validator';

const createHasSubstringEvaluator = substring => value => value.includes(substring);
const hasSubstringErrorMessage = substring => `value does not contain ${substring}`;

const hasSubstring = createValidatorFactory(
  createHasSubstringEvaluator,
  hasSubstringErrorMessage
);