Validation schema

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Validation schema is a plain JavaScript Object of a defined shape that consists of selectors and resolvers associated with them.

  • Selector is a key path that selects the field(s),

  • Resolver is a pure function that returns the next validity state of the field(s).


type ValidationSchema = {
extend?: boolean,
type?: {
[fieldType: string]: Resolvable,
name?: {
[fieldName: string]: Resolvable,
type Resolvable = Resolver | {[ruleName: string]: Resolver}
type Resolver = (params) => boolean


Here is an example of a simple validation schema:

export default {
type: {
password: ({ value }) => value.length > 6,
name: {
vatNumber: {
format: ({ value }) => /^\d{8}$/.test(value),
hashsum: ({ value }) => value[2] + value[5] === 12,

There are a few resolvers applied in the schema above:

  • For all fields of [type="password"]:

    • Anonymous resolver that validates a field's value length.

  • For all fields of [name="vatNumber"]:

    • Named format resolver that validates the format of the field's value,

    • Named hashsum resolver that validated the hash-sum of the field's value.

Priority & Exclusion

Validation resolvers are executed with the following priority relevant to the applied field (from highest to lowest):

  1. Synchronous validation:


    2. schema.type[fieldType]

  2. Asynchronous validation:

Each of these application levels is exclusive, meaning that when it rejects (returns false as the next validity state), the succeeding validators will not be executed.

Applying schema


import React from 'react'
import ReactDOM from 'react-dom'
import { FormProvider } from 'react-advanced-form'
import Root from './Root'
import validationRules from './validation/rules'
const App = () => (
<FormProvider rules={validationRules}>
<Root />
ReactDOM.render(<App />, document.getElementById('root'))


import React from 'react'
import { Form } from 'react-advanced-form'
const validationRules = {
extend: true,
name: {
username: ({ value }) => !blacklist.includes(value),
export default class ExampleForm extends React.Component {
render() {
return (
<Form rules={validationRules}>
{/* Fields */}

Extending a schema

A validation schema may be extended or overridden using a root-level extend option.

Once set to true, the current schema is deep merged with any higher scope schema (i.e. the one from FormProvider). When set to false, the current schema will override any higher scope schema.

const validationRules = {
extend: true, // extend any rules from the higher scope
name: {
myField: ({ value }) => (value !== 'foo'),