Fellipeutaka Leon Tanstack Form

TanStack Form

Version: @tanstack/react-form@latest Requires: React 18.0+, TypeScript 5.0+

Quick Setup

npm install @tanstack/react-form

import { useForm } from '@tanstack/react-form'

function App() {
  const form = useForm({
    defaultValues: {
      firstName: '',
      lastName: '',
    },
    onSubmit: async ({ value }) => {
      console.log(value)
    },
  })

  return (
    <form
      => {
        e.preventDefault()
        e.stopPropagation()
        form.handleSubmit()
      }}
    >
      <form.Field
        name="firstName"
        validators={{
          onChange: ({ value }) =>
            !value ? 'Required' : value.length < 3 ? 'Too short' : undefined,
        }}
        children={(field) => (
          <>
            <input
              value={field.state.value}
             
              => field.handleChange(e.target.value)}
            />
            {!field.state.meta.isValid && (
              <em>{field.state.meta.errors.join(', ')}</em>
            )}
          </>
        )}
      />
      <form.Subscribe
        selector={(state) => [state.canSubmit, state.isSubmitting]}
        children={([canSubmit, isSubmitting]) => (
          <button type="submit" disabled={!canSubmit}>
            {isSubmitting ? '...' : 'Submit'}
          </button>
        )}
      />
    </form>
  )
}

Production Setup (Recommended)

For production apps, use createFormHook to pre-bind reusable UI components and reduce boilerplate:

import { createFormHookContexts, createFormHook } from '@tanstack/react-form'
import { TextField, NumberField, SubmitButton } from '~/ui-library'

const { fieldContext, formContext } = createFormHookContexts()

export const { useAppForm } = createFormHook({
  fieldComponents: { TextField, NumberField },
  formComponents: { SubmitButton },
  fieldContext,
  formContext,
})

Devtools

npm install -D @tanstack/react-devtools @tanstack/react-form-devtools

import { TanStackDevtools } from '@tanstack/react-devtools'
import { formDevtoolsPlugin } from '@tanstack/react-form-devtools'

<TanStackDevtools
  config={{ hideUntilHover: true }}
  plugins={[formDevtoolsPlugin()]}
/>

Rule Categories

Critical Rules

Always Do

• Type from defaultValues — never pass generics to useForm<T>(), let TS infer from defaultValues
• Prevent default on submit — e.preventDefault(); e.stopPropagation(); form.handleSubmit()
• Use children render prop — form.Field uses render props via children={(field) => ...}
• Use form.Subscribe with selector — subscribe to specific state slices to avoid re-renders
• Use useStore with selector — useStore(form.store, (s) => s.values.name) not useStore(form.store)
• Use createFormHook in production — pre-bind components for consistency and less boilerplate
• Debounce async validators — set onChangeAsyncDebounceMs or asyncDebounceMs

Never Do

• Pass generics — useForm<MyType>() breaks the design; use typed defaultValues instead
• Skip e.preventDefault() — native form submission will bypass TanStack Form's handling
• Use useField for reactivity — use useStore(form.store) or form.Subscribe instead
• Omit selector in useStore — causes full re-render on every state change
• Use type="reset" without e.preventDefault() — native reset bypasses TanStack Form; use form.reset() explicitly
• Expect transformed values in onSubmit — Standard Schema transforms aren't applied; parse manually in onSubmit

Key Patterns

// Schema validation (form-level with Zod)
const form = useForm({
  defaultValues: { age: 0, name: '' },
  validators: {
    onChange: z.object({ age: z.number().min(13), name: z.string().min(1) }),
  },
  onSubmit: ({ value }) => console.log(value),
})

// Array fields
<form.Field name="hobbies" mode="array" children={(field) => (
  <div>
    {field.state.value.map((_, i) => (
      <form.Field key={i} name={`hobbies[${i}].name`} children={(sub) => (
        <input value={sub.state.value} => sub.handleChange(e.target.value)} />
      )} />
    ))}
    <button type="button" => field.pushValue({ name: '' })}>Add</button>
  </div>
)} />

// Linked fields (confirm password)
<form.Field name="confirm_password" validators={{
  onChangeListenTo: ['password'],
  onChange: ({ value, fieldApi }) =>
    value !== fieldApi.form.getFieldValue('password') ? 'Passwords do not match' : undefined,
}} children={(field) => <input value={field.state.value} => field.handleChange(e.target.value)} />} />

// Listeners (reset province when country changes)
<form.Field name="country" listeners={{
  onChange: ({ value }) => { form.setFieldValue('province', '') },
}} children={(field) => <input value={field.state.value} => field.handleChange(e.target.value)} />} />

// Form composition with withForm
const ChildForm = withForm({
  defaultValues: { firstName: '', lastName: '' },
  render: function Render({ form }) {
    return <form.AppField name="firstName" children={(field) => <field.TextField label="First Name" />} />
  },
})

Converted and distributed by TomeVault — claim your Tome and manage your conversions.