react-controlled-form

A package for creating controlled forms in React with baked in zod validation.
You own and control the rendered markup and the hook takes care of the state and validation.

Installation

# npm
npm i --save react-controlled-form
# yarn
yarn add react-controlled-form
# pnpm
pnpm add react-controlled-form

The Gist

import * as React from 'react'
import { useForm, FieldProps } from 'react-controlled-form'
import { z, ZodError } from 'zod'

// create our schema with validation included
const Z_RegisterInput = z.object({
  name: z.string().optional(),
  email: z.string().email(),
  // we can also pass custom messages as a second parameter
  password: z
    .string()
    .min(8, { message: 'Your password next to have at least 8 characters.' }),
})

type T_RegisterInput = z.infer<typeof Z_RegisterInput>

function Form() {
  // we create a form by passing the schema
  const { useField, handleSubmit, formProps, reset } = useForm(Z_RegisterInput)

  // now we can create our fields for each property
  // the field controls the state and validation per property
  const name = useField('name')
  const email = useField('email')
  const password = useField('password')

  function onSuccess(data: T_RegisterInput) {
    // do something with the safely parsed data
    console.log(data)
    // reset the form to its initial state
    reset()
  }

  function onFailure(error: ZodError) {
    console.error(error)
  }

  return (
    <form {...formProps} onSubmit={handleSubmit(onSuccess, onFailure)}>
      <Field label="Full Name" {...name.fieldProps}>
        <TextInput {...name.inputProps} />
      </Field>
      <Field label="E-Mail" {...email.fieldProps}>
        <TextInput type="email" {...email.inputProps} />
      </Field>
      <Field label="Password" {...password.fieldProps}>
        <TextInput type="password" {...password.inputProps} />
      </Field>
      <button type="submit">Login</button>
    </form>
  )
}

In order for it to reflect UX bad practices, we need to build some lightweight wrappers around our actual input components.
Here's a very simple example of how this could look like:

// field.fieldProps includes the errorMessage as well as the name reference for the input
function Field({
  children,
  label,
  name,
  errorMessage,
  required,
}: PropsWithChildren<FieldProps & { label: string }>) {
  return (
    <div style={{ gap: 4 }}>
      <label htmlFor={name}>
        {label}
        {required ? '' : ' (optional)'}
      </label>
      {children}
      <p style={{ color: 'red' }}>{errorMessage}</p>
    </div>
  )
}

// field.inputProps returns a valid boolean next to default input props
// we can use it to highlight a validation error
function TextInput({
  valid,
  ...props
}: React.JSX.IntrinsicElements['input'] & { valid: boolean }) {
  return <input {...props} style={{ borderColor: valid ? 'black' : 'red' }} />
}

API Reference

useForm

The core API that connects the form with a zod schema and returns a set of helpers to manage the state and render the actual markup.

Parameter	Type	Default	Description
schema	ZodObject		A valid zod object schema
formatErrorMessage	(error: ZodIssue, name: string) => string	(error) => error.message	A custom formatter that receives the raw zod issue

import { z } from 'zod'

const Z_Input = z.object({
  name: z.string().optional(),
  email: z.string().email(),
  // we can also pass custom messages as a second parameter
  password: z
    .string()
    .min(8, { message: 'Your password next to have at least 8 characters.' }),
})

type T_Input = z.infer<typeof Z_Input>

// usage inside react components
const { useField, handleSubmit, reset, formProps } = useForm(Z_Input)

formatErrorMessage

The preferred way to handle custom error messages would be to add them to the schema directly.
In some cases e.g. when receiving the schema from an API or when having to localise the error, we can leverage this helper.

import { ZodIssue } from 'zod'

// Note: the type is ZodIssue and not ZodError since we always only show the first error
function formatErrorMessage(error: ZodIssue, name: string) {
  switch (error.code) {
    case 'too_small':
      return `This field requires at least ${error.minimum} characters.`
    default:
      return error.message
  }
}

useField

A hook that manages the field state and returns the relevant HTML attributes to render our inputs.
Also returns a set of helpers to manually update and reset the field.

Parameter	Type	Default	Description
name	keyof z.infer<typeof schema>		The name of the schema property that this field connects to
initialField	{ value: any, disabled: boolean, touched: boolean }	{ value: "", disabled: false, touched: false }	Initial field data

const { inputProps, fieldProps, update, reset } = useField('email')

inputProps

type InputProps = {
  onChange: (e: React.ChangeEvent<HTMLElement>) => void
  value: any
  disabled: boolean
  valid: boolean
  name: string
}

fieldProps

type FieldProps = {
  name: string
  required: boolean
  errorMessage?: string
}

update

Programmatically change the data of a field. Useful e.g. when receiving data from an API.

Note: If you know the data upfront, prefer to pass it to the useField hook directly though.

update({
  value: 'Foo',
  touched: true,
})

reset

Resets the field back to its initial field data.

reset()

handleSubmit

Helper that wraps the native onSubmit event on <form> elements.
It prevents default action execution and parses the form data using the zod schema.

Parameter	Type	Description
onSuccess	(data: z.infer<typeof schema>)	Callback on successful safe parse of the form data
onFailure	(error: ZodError)	Callback on failed safe parse

import { ZodError } from 'zod'

function onSuccess(data: T_Input) {
  console.log(data)
}

function onFailure(error: ZodError) {
  console.error(error)
}

// <form> onSubmit handler
const onSubmit = handleSubmit(onSuccess, onFailure)

reset

Resets the form fields back to their initial field data. Helpful when trying to clear a form after a successful submit.

Note: This API is similar to the reset helper that the useField hook returns. The only difference is that it resets all fields.

reset()

formProps

An object that contains props that are passed to the native <form> element. Currently only consists of a single prop:

const formProps = {
  noValidate: true,
}

License

react-controlled-form is licensed under the MIT License.
Documentation is licensed under Creative Common License.
Created with ♥ by @robinweser and all the great contributors.