Type coercions

But to make our server validations work, we'll need to coerce our FormData into the correct types. Let's use z.preprocess for that.

lines of code
import { Form } from '@remix-run/react'
import { ActionFunction, redirect, json } from '@remix-run/node'
import Label from '~/ui/label'
import Input from '~/ui/input'
import Select from '~/ui/select'
import TextArea from '~/ui/text-area'
import Button from '~/ui/button'
import { useActionData } from '@remix-run/react'
import { z } from 'zod'

function parseDate(value: unknown) {
  const [year, month, day] = String(value).split('-').map(Number)
  return new Date(year, month - 1, day)

const reservationSchema = z.object({
  city: z.enum(['saltLakeCity', 'lasVegas', 'losAngeles']),
  checkIn: z.preprocess(parseDate, z.date()),
  checkOut: z.preprocess(parseDate, z.date()),
  adults: z.preprocess(Number, z.number().int().positive()),
  children: z.preprocess(Number, z.number().int()),
  bedrooms: z.preprocess(Number, z.number().int().positive()),
  specialRequests: z.string().optional(),

async function makeReservation(values: z.infer<typeof reservationSchema>) {
  // Here you would store data instead

type ActionData = { errors: z.ZodIssue[] }

export const action: ActionFunction = async ({ request }) => {
  const formValues = Object.fromEntries(await request.formData())
  const result = reservationSchema.safeParse(formValues)

  if (result.success) {
    await makeReservation(result.data)
    return redirect('conf/success/03')

  return json<ActionData>({ errors: result.error.issues })

function renderError(name: string) {
  const errors = useActionData<ActionData>()?.errors
  const message = errors?.find(({ path }) => path[0] === name)?.message

  if (!message) return null

  return <div className="mt-1 text-red-500">{message}</div>

export default function Component() {
  return (
    <Form method="post" className="flex flex-col space-y-4">
        <Label htmlFor="city">City</Label>
        <Select name="city" id="city">
          <option value="saltLakeCity">Salt Lake City</option>
          <option value="lasVegas">Las Vegas</option>
          <option value="losAngeles">Los Angeles</option>
        <FieldError name="city" />
      <div className="flex w-full space-x-4">
        <div className="flex-1">
          <Label htmlFor="checkIn">Check In</Label>
          <Input name="checkIn" id="checkIn" type="date" />
          <FieldError name="checkIn" />
        <div className="flex-1">
          <Label htmlFor="checkOut">Check Out</Label>
          <Input name="checkOut" id="checkOut" type="date" />
          <FieldError name="checkOut" />
      <div className="flex w-full space-x-4">
        <div className="flex-1">
          <Label htmlFor="adults">Adults</Label>
          <Input name="adults" id="adults" />
          <FieldError name="adults" />
        <div className="flex-1">
          <Label htmlFor="children">Children</Label>
          <Input name="children" id="children" />
          <FieldError name="children" />
        <div className="flex-1">
          <Label htmlFor="bedrooms">Bedrooms</Label>
          <Input name="bedrooms" id="bedrooms" />
          <FieldError name="bedrooms" />
        <Label htmlFor="specialRequests">Special Requests</Label>
        <TextArea name="specialRequests" id="specialRequests" />
        <FieldError name="specialRequests" />
      <Button>Make reservation</Button>