ValiValue

Easy and opinionated validation.

Installation

npm install valivalue

Usage

Default validator

ValiValue exports a default validator that can be used to perform some pre-implemented validations on:

• objects
• strings
• numbers
• timestamps (Luxon DateTime)

Validation methods follow a simple format:

validator.[type].[method]([value to validate], [validation parameter, ...], [subject], [error message factory])

// examples
import valivalue from "valivalue";

validator.timestamps.validateIsInFuture(DateTime.fromMillis(), "Delivery date");
validator.strings.validateMinAndMaxLength("John", 2, 64, "First name");
validator.numbers.validateMinValue(
  5, 
  12, 
  'Age', 
  (subject, value, min) => `${subject} should at least be ${min}, but was ${value}.`
);

If validation fails, an error will be thrown with a human-readable message:

import validator from "valivalue";

// Throws error with message "My object is null.".
validator.objects.validateNotNull(null, "My object");

// Throws error with message "Your object is undefined.".
validator.objects.validateNotNull(null, "Your object");

// Throws error with message "Age must be a positive number.".
validator.numbers.validateIsPositive(-1, "Age");

Values that are nullable (objects, strings and timestamps) are not automatically validated that they are not null or undefined. You should validate this using the objects validator:

import valivalue from "valivalue";

valivalue.objects.validateNotNull(null);
valivalue.objects.validateNotUndefined(undefined);
valivalue.objects.validateNotNullOrUndefined({});

null and undefined are 2 different things for the objects validator.

Reporting validator

Valivalue also exports a reporting validator, which does not throw but returns an error report:

import { reporting } from "valivalue";

const { numbers } = reporting;

const validationReport = numbers.validateIsEven(1);

const isSuccess = validationReport.isSuccess();
const isFailure = validationReport.isFailure();
const validatedValue = validationReport.value;
const validationError = validationReport.error;

validationReport.throw(); // Only throws if the validation failed.

Chainable validator

Valivalue also exports a chainable validator, which returns itself after each validation and keeps track of all validation failures:

import { chainable } from "valivalue";

const firstName = "Some input value";

const result = chainable()
                  .objects.validateNotNullOrUndefined(firstName, 'First name')
                  .strings.validateMinAndMaxLength(firstName, 1, 32, 'First name')
                  .strings.validateDoesNotContainCaseInsensitive(firstName, [ /* a list of swear words */], 'First name');

if (result.isFailure()) {
  console.error('Validation failed', results.errors);
}

If you call throw on the chainable validator, the first validation error is thrown.

You can also configure the chainable validator to throw directly on a failed validation:

import { chainable } from "valivalue";

chainable(true)
  .strings.validateNotEmpty("") // Throws directly, does not continue validation
  .numbers.validateIsEven(1);