Form

Building forms with React Hook Form and Zod.

Dependencies

Forms are tricky. They are one of the most common things you'll build in a web application, but also one of the most complex.

Well-designed HTML forms are:

Well-structured and semantically correct.
Easy to use and navigate (keyboard).
Accessible with ARIA attributes and proper labels.
Has support for client and server side validation.
Well-styled and consistent with the rest of the application.

In this guide, we will take a look at building forms with react-hook-form and zod. We're going to use a <FormField /> component to compose accessible forms using Radix UI components.

Features

The <Form /> component is a wrapper around the react-hook-form library. It provides a few things:

Composable components for building forms.
A <FormField /> component for building controlled form fields.
Form validation using zod.
Handles accessibility and error messages.
Uses React.useId() for generating unique IDs.
Applies the correct aria attributes to form fields based on states.
Built to work with all Radix UI components.
Bring your own schema library. We use zod but you can use anything you want.
You have full control over the markup and styling.

Anatomy

<Form>
  <FormField
    control={...}
    name='...'
    render={() => (
      <FormItem>
        <FormLabel />
        <FormControl>
          { /* Your form field */}
        </FormControl>
        <FormDescription />
        <FormMessage />
      </FormItem>
    )}
  />
</Form>

Example

const form = useForm()
 
<FormField
  control={form.control}
  name='username'
  render={({ field }) => (
    <FormItem>
      <FormLabel>Username</FormLabel>
      <FormControl>
        <Input placeholder='codingcodax' {...field} />
      </FormControl>
      <FormDescription>This is your public display name.</FormDescription>
      <FormMessage />
    </FormItem>
  )}
/>

Installation

npx @kosori/cli add components form

Usage

Create a form schema

Define the shape of your form using a Zod schema. You can read more about using Zod in the Zod documentation.

'use client';
 
import { z } from 'zod'; 
 

const formSchema = z.object({
  username: z.string().min(2).max(50),
});

Define a form

'use client';
 

import { zodResolver } from '@hookform/resolvers/zod';
import { useForm } from 'react-hook-form';
import { z } from 'zod';
 
const formSchema = z.object({
  username: z.string().min(2, {
    message: 'Username must be at least 2 characters.',
  }),
});
 
export const ProfileForm = () => {

  // 1. Define your form.
  const form = useForm<z.infer<typeof formSchema>>({
    resolver: zodResolver(formSchema),
    defaultValues: {
      username: '',
    },
  });
 

  // 2. Define a submit handler.
  const onSubmit = (values: z.infer<typeof formSchema>) => {
    // Do something with the form values.
    // ✅ This will be type-safe and validated.
    console.log(values);
  };
};

Since FormField is using a controlled component, you need to provide a default value for the field. See the React Hook Form docs to learn more about controlled components.

Build your form

We can now use the <Form /> components to build our form.

'use client';
 
import { zodResolver } from '@hookform/resolvers/zod';
import { useForm } from 'react-hook-form';
import { z } from 'zod';
 

import { Button } from '~/components/ui/button';
import {
  Form,
  FormControl,
  FormDescription,
  FormField,
  FormItem,
  FormLabel,
  FormMessage,
} from '~/components/ui/form';
import { Input } from '~/components/ui/input';
 
const formSchema = z.object({
  username: z.string().min(2, {
    message: 'Username must be at least 2 characters.',
  }),
});
 
export const ProfileForm = () => {
  // ...
 

  return (
    <Form {...form}>
      <form onSubmit={form.handleSubmit(onSubmit)} className='space-y-8'>
        <FormField
          control={form.control}
          name='username'
          render={({ field }) => (
            <FormItem>
              <FormLabel>Username</FormLabel>
              <FormControl>
                <Input placeholder='codingcodax' {...field} />
              </FormControl>
              <FormDescription>
                This is your public display name.
              </FormDescription>
              <FormMessage />
            </FormItem>
          )}
        />
        <Button type='submit'>Submit</Button>
      </form>
    </Form>
  )
}

Done

That's it. You now have a fully accessible form that is type-safe with client-side validation.

Examples

See the following links for more examples on how to use the <Form /> component with other components:

Form

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