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Form

Collect information from your users using validation rules.

Styling solution Source file Download runnable sandbox

import { Form } from "@radix-solid/primitives";
import styles from "./styles.module.css";
const FormDemo = () => <Form.Root class={styles.Root}>
		<Form.Field class={styles.Field} name="email">
			<div style={{
      "display": "flex",
      "align-items": "baseline",
      "justify-content": "space-between"
    }}>
				<Form.Label class={styles.Label}>Email</Form.Label>
				<Form.Message class={styles.Message} match="valueMissing">
					Please enter your email
				</Form.Message>
				<Form.Message class={styles.Message} match="typeMismatch">
					Please provide a valid email
				</Form.Message>
			</div>
			<Form.Control asChild>{target => target("input", {
        "class": styles.Input,
        "type": "email",
        "required": true
      })}</Form.Control>
		</Form.Field>
		<Form.Field class={styles.Field} name="question">
			<div style={{
      "display": "flex",
      "align-items": "baseline",
      "justify-content": "space-between"
    }}>
				<Form.Label class={styles.Label}>Question</Form.Label>
				<Form.Message class={styles.Message} match="valueMissing">
					Please enter a question
				</Form.Message>
			</div>
			<Form.Control asChild>{target => target("textarea", {
        "class": styles.Textarea,
        "required": true
      })}</Form.Control>
		</Form.Field>
		<Form.Submit asChild>{target => target("button", {
      "class": styles.Button,
      "style": {
        "margin-top": "10px"
      },
      children: <>
				Post question
			</>
    })}</Form.Submit>
	</Form.Root>;
export default FormDemo;

Features

Built on top of the native browser constraint validation API.
Supports built-in validation.
Supports custom validation.
Full customization of validation messages.
Accessible validation messages.
Supports client-side and server-side scenarios.
Focus is fully managed.

Anatomy

Import all parts and piece them together.

import { Form } from "@radix-solid/primitives";
export default () => <Form.Root>
		<Form.Field name="email">
			<Form.Label />
			<Form.Control />
			<Form.Message />
			<Form.ValidityState>{validity => validity?.valid ? "Valid" : null}</Form.ValidityState>
		</Form.Field>

		<Form.Message name="email" />
		<Form.ValidityState name="email">{validity => validity?.valid ? "Valid" : null}</Form.ValidityState>

		<Form.Submit />
	</Form.Root>;

API Reference

Root

Contains all the parts of a form.

Prop	Type	Default
`asChild`	`boolean`	`false`
`onClearServerErrors`	`function`	—

Field

The wrapper for a field. It handles id/name and label accessibility automatically.

Prop	Type	Default
`asChild`	`boolean`	`false`
`name*`	`string`	—
`serverInvalid`	`boolean`	—

Data attribute	Values
`[data-invalid]`	Present when the field is invalid
`[data-valid]`	Present when the field is valid

Label

A label element which is automatically wired when nested inside a Field part.

Prop	Type	Default
`asChild`	`boolean`	`false`

Data attribute	Values
`[data-invalid]`	Present when the field is invalid
`[data-valid]`	Present when the field is valid

Control

A control element (by default an input) which is automatically wired when nested inside a Field part.

Prop	Type	Default
`asChild`	`boolean`	`false`

Data attribute	Values
`[data-invalid]`	Present when the field is invalid
`[data-valid]`	Present when the field is valid

A validation message which is automatically wired (functionality and accessibility) to a given control when nested inside a Field part. It can be used for built-in and custom client-side validation, as well as server-side validation. When used outside a Field you must pass a name prop matching a field.

Form.Message accepts a match prop which is used to determine when the message should show. It matches the native HTML validity state (ValidityState on MDN) which validates against attributes such as required, min, max. The message will show if the given match is true on the control’s validity state.

You can also pass a function to match to provide custom validation rules.

Prop	Type	Default
`asChild`	`boolean`	`false`
`match`	`Matcher`	—
`forceMatch`	`boolean`	`false`
`name`	`string`	—

ValidityState

Use this render-prop component to access a given field’s validity state in render (see ValidityState on MDN). A field's validity is available automatically when nested inside a Field part, otherwise you must pass a name prop to associate it.

Prop	Type	Default
`children`	`function`	—
`name`	`string`	—

Submit

The submit button.

Prop	Type	Default
`asChild`	`boolean`	`false`

Examples

Composing with your own components

Using asChild you can compose the Form primitive parts with your own components.

<Form.Field name="name">
	<Form.Label>Full name</Form.Label>
	<Form.Control asChild>{target => target(TextField.Root, {
        "variant": "surface"
      })}</Form.Control>
</Form.Field>

It can also be used to compose other types of controls, such as a select:

<Form.Field name="country">
	<Form.Label>Country</Form.Label>
	<Form.Control asChild>{target => target("select", {
        children: <>
			<option value="uk">United Kingdom</option>…
		</>
      })}</Form.Control>
</Form.Field>

Note: At the moment, it is not possible to compose Form with Radix's other form primitives such as Checkbox, Select, etc. We are working on a solution for this.

Providing your own validation messages

When no children are provided, Form.Message will render a default error message for the given match.

// will yield "This value is missing"
<Form.Message match="valueMissing" />;

You can provide a more meaningful message by passing your own children. This is also useful for internationalization.

// will yield "Please provide a name"
<Form.Message match="valueMissing">Please provide a name</Form.Message>;

Custom validation

On top of all the built-in client-side validation matches described above you can also provide your own custom validation whilst still making use of the platform's validation abilities. It uses the customError type present in the constraint validition API.

You can pass your own validation function into the match prop on Form.Message. Here's an example:

<Form.Field name="name">
	<Form.Label>Full name</Form.Label>
	<Form.Control />
	<Form.Message match={(value, formData) => value !== "John"}>
		Only John is allowed.
	</Form.Message>
</Form.Field>

match will be called with the current value of the control as first argument and the entire FormData as second argument. match can also be an async function (or return a promise) to perform async validation.

Styling based on validity

We add data-valid and data-invalid attributes to the relevant parts. Use it to style your components accordingly. Here is an example styling the Label part.

//index.tsx

import { Form } from "@radix-solid/primitives";
export default () => <Form.Root>
		<Form.Field name="email">
			<Form.Label class="FormLabel">Email</Form.Label>
			<Form.Control type="email" />
		</Form.Field>
	</Form.Root>;

/* styles.css */
.FormLabel[data-invalid] {
	color: red;
}
.FormLabel[data-valid] {
	color: green;
}

Accessing the validity state for more control

You may need to access the raw validity state of a field in order to display your own icons, or interface with a component library via it's defined props. You can do this by using the Form.ValidityState part:

<Form.Field name="name">
	<Form.Label>Full name</Form.Label>
	<Form.ValidityState>
		{validity => <Form.Control asChild>{target => target(TextField.Root, {
          "variant": "surface",
          "aria-invalid": validity ? validity.valid ? "false" : "true" : undefined
        })}</Form.Control>}
	</Form.ValidityState>
</Form.Field>

Server-side validation

The component also supports server-side validation using the same Form.Message component. You can re-use the same messages you defined for client-side errors by passing a forceMatch prop which will force the message to show regardless of the client-side matching logic.

If the message doesn't exist on the client-side, you can render a Form.Message without a match too. The field is marked as invalid by passing a serverInvalid boolean prop to the Form.Field part.

Pass your application's submit function. It resolves to invalid-field flags; request failures are displayed separately.

import { createSignal } from "solid-js";
import { Form } from "@radix-solid/primitives";
type ServerErrors = { email: boolean; password: boolean };
function Page(props: { submit: (data: FormData) => Promise<ServerErrors> }) {
  const [serverErrors, setServerErrors] = createSignal<ServerErrors>({
    email: false,
    password: false
  });
  const [requestError, setRequestError] = createSignal<string>();
  return <Form.Root
  // Only triggered after client-side validation succeeds.
  onSubmit={async event => {
    event.preventDefault();
    setRequestError(undefined);
    try {
      setServerErrors(await props.submit(new FormData(event.currentTarget)));
    } catch (error) {
      setRequestError(error instanceof Error ? error.message : "Unable to submit the form.");
    }
  }} onClearServerErrors={() => setServerErrors({
    email: false,
    password: false
  })}>
			<Form.Field name="email" serverInvalid={serverErrors().email}>
				<Form.Label>Email address</Form.Label>
				<Form.Control type="email" required />
				<Form.Message match="valueMissing">
					Please enter your email.
				</Form.Message>
				<Form.Message match="typeMismatch" forceMatch={serverErrors().email}>
					Please provide a valid email.
				</Form.Message>
			</Form.Field>

			<Form.Field name="password" serverInvalid={serverErrors().password}>
				<Form.Label>Password</Form.Label>
				<Form.Control type="password" required />
				<Form.Message match="valueMissing">
					Please enter a password.
				</Form.Message>
				{serverErrors().password && <Form.Message>
						Please provide a valid password. It should contain at least 1 number
						and 1 special character.
					</Form.Message>}
			</Form.Field>
			{requestError() && <p role="alert">{requestError()}</p>}

			<Form.Submit>Submit</Form.Submit>
		</Form.Root>;
}

You should clear the server errors using the onClearServerErrors callback prop on the Form.Root part. It will clear the server errors before the form is re-submitted, and when the form is reset.

In addition, this provides control over when to reset single server errors. For example you could reset the email server error as soon as the user edits it:

function EmailField(props: { serverInvalid: boolean; onClearServerError: () => void }) {
  return <Form.Field name="email" serverInvalid={props.serverInvalid}>
    <Form.Label>Email address</Form.Label>
    <Form.Control type="email" onInput={props.onClearServerError} />
    <Form.Message match="valueMissing">Please enter your email.</Form.Message>
    <Form.Message match="typeMismatch" forceMatch={props.serverInvalid}>
      Please provide a valid email.
    </Form.Message>
  </Form.Field>;
}

Accessibility

The component follows the "inline errors" pattern for validation:

Label and control are associated using the name provided on Form.Field
When one or more client-side error messages display, they are automatically associated with their matching control and announced accordingly
Focus is moved to the first invalid control