@felte/validator-yup

A package to help you handle validation with Yup in Felte.

Installation

npm install --save @felte/validator-yup yup

# Or, if you use yarn

yarn add @felte/validator-yup yup

Usage

Call validator with an object containing your Yup schema in the schema property. The result of the call can be passed as an extender to Felte:

import { validator } from '@felte/validator-yup';
import * as yup from 'yup';

const schema = yup.object({
  email: yup.string().email().required(),
  password: yup.string().required(),
});

const { form } = createForm({
  // ...
  extend: validator({ schema }), // or `extend: [validator({ schema })],`
  // ...
});

OR use the validateSchema function directly in the validate option of createForm. (No need to extend Felte).

import { validateSchema } from '@felte/validator-yup';
import * as yup from 'yup';

const schema = yup.object({
  email: yup.string().email().required(),
  password: yup.string().required(),
});

const { form } = createForm({
  // ...
  validate: validateSchema(schema),
  // ...
});

Casting values

Unlike yup, by default this validator does not cast values. If you wish to have this behaviour you may set the castValues property to true on the validator's configuration:

const { form } = createForm({
  //...
  extend: validator({ schema, castValues: true }),
  //...
});

NOTE: yup throws if your schema fails to cast, we do not catch this errors so make sure your schema handles this appropriately to prevent your app from crashing. For example, lets assume we have a text input that should be cast to an integer. yup's number rule would throw an error if a string is set so, in order to prevent your app from crashing, a custom rule would be needed:

const schema = yup.object({
  shouldBeNumber: yup
    .mixed()
    .test('number', 'Must be a number', value => !isNaN(value))
    .transform(value => parseInt(value, 10)),
});

Warnings

Optionally, you can tell this package to assign the results of your validations to your warnings store by setting the level property of the validator function to warning. It's error by default:

import { validator } from '@felte/validator-yup';
import * as yup from 'yup';

const validateSchema = yup.object({
  email: yup.string().email().required(),
  password: yup.string().required(),
});

// We only warn if the user has already started typing a value
const warnSchema = yup.object({
  password: yup
    .string()
    .test('is-secure', 'password is not secure', (value) =>
      value ? value.length > 8 : true
    ),
});

const { form } = createForm({
  // ...
  extend: [
    validator({ schema }),
    validator({ schema: warnSchema, level: 'warning' }),
  ],
  // ...
});

Typescript

Yup allows you to infer the type of your schema using yup.InferType. This can be used so you don't need to create a type for your form's data:

import * as yup from 'yup';

const schema = yup.object({
  email: yup.string().email().required(),
  password: yup.string().required(),
});

const { form } = createForm<yup.InferType<typeof schema>>(/* ... */);