| --- |
| title: How to create forms with API Routes |
| nav_title: Forms |
| description: Learn how to handle form submissions and data mutations with Next.js. |
| --- |
|
|
| Forms enable you to create and update data in web applications. Next.js provides a powerful way to handle data mutations using **API Routes**. This guide will walk you through how to handle form submission on the server. |
|
|
| |
|
|
| To handle form submissions on the server, create an API endpoint securely mutate data. |
|
|
| ```ts filename="pages/api/submit.ts" switcher |
| import type { NextApiRequest, NextApiResponse } from 'next' |
| |
| export default async function handler( |
| req: NextApiRequest, |
| res: NextApiResponse |
| ) { |
| const data = req.body |
| const id = await createItem(data) |
| res.status(200).json({ id }) |
| } |
| ``` |
|
|
| ```js filename="pages/api/submit.js" switcher |
| export default function handler(req, res) { |
| const data = req.body |
| |
| |
| |
| res.status(200).json({ data }) |
| } |
| ``` |
|
|
| Then, call the API Route from the client with an event handler: |
|
|
| ```tsx filename="pages/index.tsx" switcher |
| import { FormEvent } from 'react' |
| |
| export default function Page() { |
| async function onSubmit(event: FormEvent<HTMLFormElement>) { |
| event.preventDefault() |
| |
| const formData = new FormData(event.currentTarget) |
| const response = await fetch('/api/submit', { |
| method: 'POST', |
| body: formData, |
| }) |
| |
| |
| const data = await response.json() |
| |
| } |
| |
| return ( |
| <form onSubmit={onSubmit}> |
| <input type="text" name="name" /> |
| <button type="submit">Submit</button> |
| </form> |
| ) |
| } |
| ``` |
|
|
| ```jsx filename="pages/index.jsx" switcher |
| export default function Page() { |
| async function onSubmit(event) { |
| event.preventDefault() |
| |
| const formData = new FormData(event.target) |
| const response = await fetch('/api/submit', { |
| method: 'POST', |
| body: formData, |
| }) |
| |
| |
| const data = await response.json() |
| |
| } |
| |
| return ( |
| <form onSubmit={onSubmit}> |
| <input type="text" name="name" /> |
| <button type="submit">Submit</button> |
| </form> |
| ) |
| } |
| ``` |
|
|
| > **Good to know:** |
| > |
| > - API Routes [do not specify CORS headers](https://developer.mozilla.org/docs/Web/HTTP/CORS), meaning they are same-origin only by default. |
| > - Since API Routes run on the server, we're able to use sensitive values (like API keys) through [Environment Variables](/docs/pages/guides/environment-variables) without exposing them to the client. This is critical for the security of your application. |
| |
| ## Form validation |
| |
| We recommend using HTML validation like `required` and `type="email"` for basic client-side form validation. |
| |
| For more advanced server-side validation, you can use a schema validation library like [zod](https://zod.dev/) to validate the form fields before mutating the data: |
| |
| ```ts filename="pages/api/submit.ts" switcher |
| import type { NextApiRequest, NextApiResponse } from 'next' |
| import { z } from 'zod' |
| |
| const schema = z.object({ |
| // ... |
| }) |
| |
| export default async function handler( |
| req: NextApiRequest, |
| res: NextApiResponse |
| ) { |
| const parsed = schema.parse(req.body) |
| // ... |
| } |
| ``` |
| |
| ```js filename="pages/api/submit.js" switcher |
| import { z } from 'zod' |
| |
| const schema = z.object({ |
| // ... |
| }) |
| |
| export default async function handler(req, res) { |
| const parsed = schema.parse(req.body) |
| // ... |
| } |
| ``` |
| |
| ### Error handling |
| |
| You can use React state to show an error message when a form submission fails: |
| |
| ```tsx filename="pages/index.tsx" switcher |
| import React, { useState, FormEvent } from 'react' |
| |
| export default function Page() { |
| const [isLoading, setIsLoading] = useState<boolean>(false) |
| const [error, setError] = useState<string | null>(null) |
| |
| async function onSubmit(event: FormEvent<HTMLFormElement>) { |
| event.preventDefault() |
| setIsLoading(true) |
| setError(null) // Clear previous errors when a new request starts |
| |
| try { |
| const formData = new FormData(event.currentTarget) |
| const response = await fetch('/api/submit', { |
| method: 'POST', |
| body: formData, |
| }) |
| |
| if (!response.ok) { |
| throw new Error('Failed to submit the data. Please try again.') |
| } |
| |
| // Handle response if necessary |
| const data = await response.json() |
| // ... |
| } catch (error) { |
| // Capture the error message to display to the user |
| setError(error.message) |
| console.error(error) |
| } finally { |
| setIsLoading(false) |
| } |
| } |
| |
| return ( |
| <div> |
| {error && <div style={{ color: 'red' }}>{error}</div>} |
| <form onSubmit={onSubmit}> |
| <input type="text" name="name" /> |
| <button type="submit" disabled={isLoading}> |
| {isLoading ? 'Loading...' : 'Submit'} |
| </button> |
| </form> |
| </div> |
| ) |
| } |
| ``` |
| |
| ```jsx filename="pages/index.jsx" switcher |
| import React, { useState } from 'react' |
| |
| export default function Page() { |
| const [isLoading, setIsLoading] = useState(false) |
| const [error, setError] = useState(null) |
| |
| async function onSubmit(event) { |
| event.preventDefault() |
| setIsLoading(true) |
| setError(null) // Clear previous errors when a new request starts |
| |
| try { |
| const formData = new FormData(event.currentTarget) |
| const response = await fetch('/api/submit', { |
| method: 'POST', |
| body: formData, |
| }) |
| |
| if (!response.ok) { |
| throw new Error('Failed to submit the data. Please try again.') |
| } |
| |
| // Handle response if necessary |
| const data = await response.json() |
| // ... |
| } catch (error) { |
| // Capture the error message to display to the user |
| setError(error.message) |
| console.error(error) |
| } finally { |
| setIsLoading(false) |
| } |
| } |
| |
| return ( |
| <div> |
| {error && <div style={{ color: 'red' }}>{error}</div>} |
| <form onSubmit={onSubmit}> |
| <input type="text" name="name" /> |
| <button type="submit" disabled={isLoading}> |
| {isLoading ? 'Loading...' : 'Submit'} |
| </button> |
| </form> |
| </div> |
| ) |
| } |
| ``` |
| |
| ## Displaying loading state |
| |
| You can use React state to show a loading state when a form is submitting on the server: |
| |
| ```tsx filename="pages/index.tsx" switcher |
| import React, { useState, FormEvent } from 'react' |
| |
| export default function Page() { |
| const [isLoading, setIsLoading] = useState<boolean>(false) |
| |
| async function onSubmit(event: FormEvent<HTMLFormElement>) { |
| event.preventDefault() |
| setIsLoading(true) // Set loading to true when the request starts |
| |
| try { |
| const formData = new FormData(event.currentTarget) |
| const response = await fetch('/api/submit', { |
| method: 'POST', |
| body: formData, |
| }) |
| |
| // Handle response if necessary |
| const data = await response.json() |
| // ... |
| } catch (error) { |
| // Handle error if necessary |
| console.error(error) |
| } finally { |
| setIsLoading(false) // Set loading to false when the request completes |
| } |
| } |
| |
| return ( |
| <form onSubmit={onSubmit}> |
| <input type="text" name="name" /> |
| <button type="submit" disabled={isLoading}> |
| {isLoading ? 'Loading...' : 'Submit'} |
| </button> |
| </form> |
| ) |
| } |
| ``` |
| |
| ```jsx filename="pages/index.jsx" switcher |
| import React, { useState } from 'react' |
| |
| export default function Page() { |
| const [isLoading, setIsLoading] = useState(false) |
| |
| async function onSubmit(event) { |
| event.preventDefault() |
| setIsLoading(true) // Set loading to true when the request starts |
| |
| try { |
| const formData = new FormData(event.currentTarget) |
| const response = await fetch('/api/submit', { |
| method: 'POST', |
| body: formData, |
| }) |
| |
| // Handle response if necessary |
| const data = await response.json() |
| // ... |
| } catch (error) { |
| // Handle error if necessary |
| console.error(error) |
| } finally { |
| setIsLoading(false) // Set loading to false when the request completes |
| } |
| } |
| |
| return ( |
| <form onSubmit={onSubmit}> |
| <input type="text" name="name" /> |
| <button type="submit" disabled={isLoading}> |
| {isLoading ? 'Loading...' : 'Submit'} |
| </button> |
| </form> |
| ) |
| } |
| ``` |
| |
| ### Redirecting |
| |
| If you would like to redirect the user to a different route after a mutation, you can [`redirect`](/docs/pages/building-your-application/routing/api-routes#response-helpers) to any absolute or relative URL: |
| |
| ```ts filename="pages/api/submit.ts" switcher |
| import type { NextApiRequest, NextApiResponse } from 'next' |
| |
| export default async function handler( |
| req: NextApiRequest, |
| res: NextApiResponse |
| ) { |
| const id = await addPost() |
| res.redirect(307, `/post/${id}`) |
| } |
| ``` |
| |
| ```js filename="pages/api/submit.js" switcher |
| export default async function handler(req, res) { |
| const id = await addPost() |
| res.redirect(307, `/post/${id}`) |
| } |
| ``` |
| |
