Unstyled Form Control

The FormControlUnstyled component is a utility that lets you associate a form input with auxiliary components, such as labels, error indicators, or helper text.

Introduction

FormControlUnstyled is a utility that wraps an input component with other associated components in order to make the state of the input available to those components.

For instance, you may want to show an additional element asking the user to enter a value if the input is empty, or display a warning icon if the entered value is incorrect.

Component

Usage

After installation, you can start building with this component using the following basic elements:

import FormControlUnstyled from '@mui/base/FormControlUnstyled';

export default function MyApp() {
  return (
    <FormControlUnstyled>
      {/* <input> and/or other contents of the form */}
    </FormControlUnstyled>
  );
}

Basics

FormControlUnstyled wraps around the elements of a form that need access to the state of an <input>. For instance, if the form's Submit button needs to change states after the user enters information, then the component will be structured like this:

<FormControlUnstyled>
  <input>
  <button>Submit</button>
</FormControlUnstyled>

The following demo shows how to create and style a form that uses FormControlUnstyled to wrap the elements of the form. Note that it also uses the useFormControlUnstyledContext hook in order to pass props to the custom InputUnstyled—see the Hook section below for more details.

Name *

<FormControlUnstyled defaultValue="" required>
  <Label>Name</Label>
  <Input />
  <HelperText />
</FormControlUnstyled>

Hook

import { useFormControlUnstyledContext } from '@mui/base/FormControlUnstyled';

The useFormControlUnstyledContext hook reads the context provided by FormControlUnstyled. This hook lets you work with custom input components inside of the form control. You can also use it to read the form control's state and react to its changes in a custom component.

Hooks do not support slot props, but they do support customization props.

The demo below shows how to integrate this hook with its component counterpart:

CustomInput is a wrapper around a native HTML <input> that adds FormControlUnstyled integration.
ControlStateDisplay reads the state of the form control and displays it as text.

empty | not focused

Note that even though FormControlUnstyled supports both controlled and uncontrolled-style APIs (i.e. it accepts value and defaultValue props), useFormControlUnstyledContext returns only the controlled value. This way, you don't have to implement both in your custom input—FormControlUnstyled does this for you.

useFormControlUnstyledContext returns an object with the following fields:

Name	Type	Description
`disabled`	boolean	Represents the value of the FormControlUnstyled's `disabled` prop.
`error`	boolean	Represents the value of the `FormControlUnstyled` component's `error` prop. Note that it is not calculated automatically (i.e. it's not set when `required: true` and `value: ''`).
`filled`	boolean	Set to `true` if `value` is not empty.
`focused`	boolean	Set to `true` if the wrapped input has received focus.
`required`	boolean	Represents the value of the `FormControlUnstyled` component's `required` prop.
`value`	unknown	The current value of the form control.

The following callbacks are also part of the returned object—they are meant to be used when creating custom inputs:

Name	Type	Description
`onChange`	React.ChangeEvent => void	Value change handler. Should be forwarded to the inner input.
`onBlur`	() => void	Focus change handler. Should be forwarded to the inner input.
`onFocus`	() => void	Focus change handler. Should be forwarded to the inner input.

Customization

Accessing the form control state

You can access the state of the form control by providing a function as a child of the FormControlUnstyled. The state will be provided as a parameter to this function.

The following demo shows how to access the state of the form control in an InputUnstyled component nested inside of FormControlUnstyled:

<FormControlUnstyled defaultValue="" required>
  {({ filled, focused }: FormControlUnstyledState) => (
    <React.Fragment>
      <Input className={filled ? 'filled' : ''} />
      {filled && !focused && <OkMark>✔</OkMark>}
    </React.Fragment>
  )}
</FormControlUnstyled>

API

<FormControlUnstyled />