react-validated-proxy

An approach to form validation in React that makes use of ES6 Proxy, by way of @poteto's validated-proxy library.

react-validated-proxy exports a single component <Validate>, which you can use to validate changes to any object.

Install

Note: this library is in alpha and is not ready for production use.

$ npm i react-validated-proxy

Example

import Validate from 'react-validated-proxy';
import { isPresent, hasLength } from './validations';

const user = {
  firstName: 'Billy',
  lastName: 'Bob',
  // ...
};

const Adult = {
  firstName: [isPresent(), hasLength({ min: 2 })],
  lastName: [isPresent(), hasLength({ min: 2 })],
  // ...
};

<Validate model={user} as={Adult}>
  {({ model, set, reset, isPristine, hasErrors, flush }) => (
    <form onSubmit={flush}>
      <input type="text" value={model.firstName} onChange={e => set('firstName', e.target.value)} />
      <input type="text" value={model.lastName} onChange={e => set('lastName', e.target.value)} />
      <button type="submit" disabled={isPristine || hasErrors}>Save</button>
      <button type="button" onClick={reset}>Reset</button>
    </form>
  )}
</Validate>

See the full code for this example under example/. You can also clone this repo and run npm install && npm start to see the example running live.

Rationale

ES6 Proxies have many cool use cases – one of which is validating changes to objects. You can modify an object as you normally would, and a Proxy can intercept those modifications to add custom behavior.

In the case of this library, the <Validate> component accepts a model object, as well as a map of validations in the format defined by validated-proxy. <Validate> will then wrap your model in a Proxy, and pass the Proxy to your children render prop. You can then interact with the Proxy as your model, but with the added benefit of knowing when and why changes to the model are invalid. (Specifically, you can easily retrieve error messages from the Proxy.)

react-validated-proxy owes its existence to validated-proxy and ember-changeset by Lauren Tan. It's mostly an experiment in distilling ember-changeset to its framework-agnostic core.

API

`<Validate model={T} as={IValidationMap}>...</Validate>`

Pass in a data model that you want to validate, as well as a validation map of validators for your data model. The validation map should be in the format expected by validated-proxy.

const user = {
  firstName: 'Jim',
  lastName: 'Bob',
  age: 15,
};

const Adult = {
  firstName: [isPresent(), hasLength({ min: 2 })],
  lastName: [isPresent(), hasLength({ min: 2 })],
  age: isNumber({ op: '>=', value: 18 }),
};

<Validate model={user} as={Adult}>
  {({ model, set, reset, isPristine, hasErrors, flush }) => (
    <form>{/* ... */}</form>
  )}
</Validate>

<Validate> accepts a render prop as its children, and will pass the wrapped model (and some helper properties and functions) to the render prop:

interface HelperProps {
  model: BufferedProxy
  set: <T>(name: string, value: T) => void
  reset: () => void
  isPristine: boolean
  hasErrors: boolean
  flush: () => void
}

Jason Tu · GitHub @nucleartide · Twitter @nucleartide

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