README.md

🏁 React Final Form HTML5 Validation

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🏁 React Final Form HTML5 Validation is swappable replacement for 🏁 React Final Form's Field component that provides two-way HTML5 Validation bindings. The bindings are two-way because any HTML5 contraint validation errors will be added to the 🏁 Final Form state, and any field-level validation errors from 🏁 Final Form will be set into the HTML5 validity.customError state. Unfortunately, this functionality is not compatible with 🏁 React Final Form record-level validation, so the two should not be mixed.

Why not add this functionality directly into the officially bundled Field component?

Good question. The reason is that not everyone needs this functionality, and not everyone is using 🏁 React Final Form with the DOM (e.g. some people use it with React Native). Therefore it makes sense to make this a separate package. This version of Field is a thin wrapper over the official Field component, and the only Field API that this library uses/overrides is the field-level validate prop, so even if you are using this library's Field component, you will still get improvements as features are added to the 🏁 React Final Form library in the future.

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Installation

npm install --save react-final-form-html5-validation react-final-form final-form

or

yarn add react-final-form-html5-validation react-final-form final-form

Example 👀

Usage

The way you specify rules and error messages in HTML5 is by giving first a rule prop, e.g. required, min, maxLength, and then an error message prop, e.g. valueMissing, rangeUnderflow, or tooLong, respectively. This library comes with built-in English defaults for the error messages, but you will probably want to override those by passing in your own.

import { Form } from 'react-final-form'
import { Field } from 'react-final-form-html5-validation'

const MyForm = () => (
  <Form
    onSubmit={onSubmit}
    render={({ handleSubmit, pristine, invalid }) => (
      <form onSubmit={handleSubmit}>
        <div>
          <label>First Name</label>
          <Field
            name="firstName"
            component="input"
            type="text"
            placeholder="First Name"
            required
            maxLength={20}
            tooLong="That name is too long!"
            pattern="[A-Z].+"
          />
        </div>
        ...
      </form>
    )}
  />
)

Table of Contents

• Rules and Messages
• API
  • Rules
    • max?: Number
    • maxLength?: Number
    • min?: Number
    • minLength?: Number
    • pattern?: string
    • required?: boolean
    • step?: Number
  • Messages
    • badInput?: string
    • patternMismatch?: string
    • rangeOverflow?: string
    • rangeUnderflow?: string
    • stepMismatch?: string
    • tooLong?: string
    • tooShort?: string
    • typeMismatch?: string
    • valueMissing?: string
• Internationalization

Rules and Messages

These all come from the HTML Standard.

Rule	Value	Message	Meaning
		badInput	The value is invalid somehow
max	Number	rangeOverflow	The value is too high
maxLength	Number	tooLong	The value is too long
min	Number	rangeUnderflow	The value is too small
minLength	Number	tooShort	The value is too short
pattern	string	patternMismatch	The value does not match the regular expression
required	boolean	valueMissing	The value is missing
step	Number	stepMismatch	The value does not match the step granularity
		typeMismatch	The value does not match the specified type

API

In addition to all the FieldProps that you can pass to the standard Field, to an HTML5 Validation Field, you may also pass:

Rules

max?: Number

The maximum value allowed as the value for the input. If invalid, the rangeOverflow error will be displayed.

maxLength?: Number

The maximum length allowed of the input value. If invalid, the tooLong error will be displayed.

min?: Number

The minimum value allowed as the value for the input. If invalid, the rangeUnderflow error will be displayed.

minLength?: Number

The minimum length allowed of the input value. If invalid, the tooShort error will be displayed.

pattern?: string

A string regular expression to test the input value against. If invalid, the patternMismatch error will be displayed.

required?: boolean

Whether or not the field is required. If invalid, the valueMissing error will be displayed.

step?: Number

The step size between the min and max values. If invalid, the stepMismatch error will be displayed.

Messages

badInput?: string

The message to display when the input is invalid somehow.

patternMismatch?: string|(value?: any, props: Object) => string

The message to display when the value does not match the pattern specified by the pattern prop.

rangeOverflow?: string|(value?: any, props: Object) => string

The message to display when the value is higher than the max prop.

rangeUnderflow?: string|(value?: any, props: Object) => string

The message to display when the value is lower than the min prop.

stepMismatch?: string|(value?: any, props: Object) => string

The message to display the value is not one of the valid steps specified by the step prop.

tooLong?: string|(value?: any, props: Object) => string

The message to display when the value longer than the value specified by the maxLength prop.

tooShort?: string|(value?: any, props: Object) => string

The message to display when the value shorter than the value specified by the minLength prop.

typeMismatch?: string|(value?: any, props: Object) => string

The message to display when the value does not match the type prop.

valueMissing?: string|(value?: any, props: Object) => string

The message to display when the value is required, but missing.

Internationalization

If internationalization is important to your project, you should probably create a component that wraps this component, pulls the localized messages from the context, and renders:

<Field {...props} {...messages} />