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--- |
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title: How to create forms with API Routes |
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nav_title: Forms |
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description: Learn how to handle form submissions and data mutations with Next.js. |
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--- |
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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. |
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To handle form submissions on the server, create an API endpoint securely mutate data. |
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```ts filename="pages/api/submit.ts" switcher |
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import type { NextApiRequest, NextApiResponse } from 'next' |
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export default async function handler( |
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req: NextApiRequest, |
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res: NextApiResponse |
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) { |
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const data = req.body |
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const id = await createItem(data) |
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res.status(200).json({ id }) |
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} |
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``` |
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```js filename="pages/api/submit.js" switcher |
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export default function handler(req, res) { |
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const data = req.body |
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res.status(200).json({ data }) |
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} |
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``` |
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Then, call the API Route from the client with an event handler: |
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```tsx filename="pages/index.tsx" switcher |
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import { FormEvent } from 'react' |
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export default function Page() { |
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async function onSubmit(event: FormEvent<HTMLFormElement>) { |
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event.preventDefault() |
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const formData = new FormData(event.currentTarget) |
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const response = await fetch('/api/submit', { |
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method: 'POST', |
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body: formData, |
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}) |
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const data = await response.json() |
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} |
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return ( |
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<form onSubmit={onSubmit}> |
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<input type="text" name="name" /> |
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<button type="submit">Submit</button> |
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</form> |
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) |
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} |
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``` |
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```jsx filename="pages/index.jsx" switcher |
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export default function Page() { |
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async function onSubmit(event) { |
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event.preventDefault() |
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const formData = new FormData(event.target) |
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const response = await fetch('/api/submit', { |
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method: 'POST', |
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body: formData, |
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}) |
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const data = await response.json() |
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} |
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return ( |
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<form onSubmit={onSubmit}> |
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<input type="text" name="name" /> |
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<button type="submit">Submit</button> |
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</form> |
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) |
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} |
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``` |
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> **Good to know:** |
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> |
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> - API Routes [do not specify CORS headers](https://developer.mozilla.org/docs/Web/HTTP/CORS), meaning they are same-origin only by default. |
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> - 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. |
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## Form validation |
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We recommend using HTML validation like `required` and `type="email"` for basic client-side form validation. |
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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: |
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```ts filename="pages/api/submit.ts" switcher |
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import type { NextApiRequest, NextApiResponse } from 'next' |
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import { z } from 'zod' |
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const schema = z.object({ |
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// ... |
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}) |
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export default async function handler( |
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req: NextApiRequest, |
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res: NextApiResponse |
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) { |
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const parsed = schema.parse(req.body) |
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// ... |
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} |
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``` |
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```js filename="pages/api/submit.js" switcher |
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import { z } from 'zod' |
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const schema = z.object({ |
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// ... |
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}) |
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export default async function handler(req, res) { |
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const parsed = schema.parse(req.body) |
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// ... |
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} |
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``` |
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### Error handling |
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You can use React state to show an error message when a form submission fails: |
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```tsx filename="pages/index.tsx" switcher |
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import React, { useState, FormEvent } from 'react' |
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export default function Page() { |
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const [isLoading, setIsLoading] = useState<boolean>(false) |
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const [error, setError] = useState<string | null>(null) |
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async function onSubmit(event: FormEvent<HTMLFormElement>) { |
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event.preventDefault() |
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setIsLoading(true) |
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setError(null) // Clear previous errors when a new request starts |
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try { |
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const formData = new FormData(event.currentTarget) |
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const response = await fetch('/api/submit', { |
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method: 'POST', |
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body: formData, |
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}) |
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if (!response.ok) { |
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throw new Error('Failed to submit the data. Please try again.') |
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} |
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// Handle response if necessary |
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const data = await response.json() |
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// ... |
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} catch (error) { |
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// Capture the error message to display to the user |
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setError(error.message) |
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console.error(error) |
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} finally { |
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setIsLoading(false) |
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} |
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} |
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return ( |
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<div> |
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{error && <div style={{ color: 'red' }}>{error}</div>} |
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<form onSubmit={onSubmit}> |
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<input type="text" name="name" /> |
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<button type="submit" disabled={isLoading}> |
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{isLoading ? 'Loading...' : 'Submit'} |
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</button> |
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</form> |
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</div> |
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) |
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} |
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``` |
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```jsx filename="pages/index.jsx" switcher |
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import React, { useState } from 'react' |
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export default function Page() { |
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const [isLoading, setIsLoading] = useState(false) |
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const [error, setError] = useState(null) |
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async function onSubmit(event) { |
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event.preventDefault() |
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setIsLoading(true) |
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setError(null) // Clear previous errors when a new request starts |
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try { |
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const formData = new FormData(event.currentTarget) |
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const response = await fetch('/api/submit', { |
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method: 'POST', |
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body: formData, |
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}) |
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if (!response.ok) { |
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throw new Error('Failed to submit the data. Please try again.') |
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} |
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// Handle response if necessary |
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const data = await response.json() |
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// ... |
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} catch (error) { |
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// Capture the error message to display to the user |
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setError(error.message) |
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console.error(error) |
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} finally { |
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setIsLoading(false) |
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} |
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} |
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return ( |
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<div> |
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{error && <div style={{ color: 'red' }}>{error}</div>} |
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<form onSubmit={onSubmit}> |
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<input type="text" name="name" /> |
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<button type="submit" disabled={isLoading}> |
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{isLoading ? 'Loading...' : 'Submit'} |
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</button> |
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</form> |
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</div> |
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) |
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} |
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``` |
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## Displaying loading state |
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You can use React state to show a loading state when a form is submitting on the server: |
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```tsx filename="pages/index.tsx" switcher |
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import React, { useState, FormEvent } from 'react' |
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export default function Page() { |
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const [isLoading, setIsLoading] = useState<boolean>(false) |
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async function onSubmit(event: FormEvent<HTMLFormElement>) { |
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event.preventDefault() |
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setIsLoading(true) // Set loading to true when the request starts |
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try { |
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const formData = new FormData(event.currentTarget) |
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const response = await fetch('/api/submit', { |
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method: 'POST', |
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body: formData, |
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}) |
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// Handle response if necessary |
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const data = await response.json() |
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// ... |
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} catch (error) { |
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// Handle error if necessary |
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console.error(error) |
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} finally { |
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setIsLoading(false) // Set loading to false when the request completes |
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} |
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} |
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return ( |
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<form onSubmit={onSubmit}> |
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<input type="text" name="name" /> |
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<button type="submit" disabled={isLoading}> |
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{isLoading ? 'Loading...' : 'Submit'} |
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</button> |
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</form> |
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) |
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} |
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``` |
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```jsx filename="pages/index.jsx" switcher |
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import React, { useState } from 'react' |
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export default function Page() { |
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const [isLoading, setIsLoading] = useState(false) |
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async function onSubmit(event) { |
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event.preventDefault() |
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setIsLoading(true) // Set loading to true when the request starts |
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try { |
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const formData = new FormData(event.currentTarget) |
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const response = await fetch('/api/submit', { |
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method: 'POST', |
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body: formData, |
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}) |
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// Handle response if necessary |
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const data = await response.json() |
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// ... |
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} catch (error) { |
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// Handle error if necessary |
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console.error(error) |
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} finally { |
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setIsLoading(false) // Set loading to false when the request completes |
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} |
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} |
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return ( |
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<form onSubmit={onSubmit}> |
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<input type="text" name="name" /> |
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<button type="submit" disabled={isLoading}> |
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{isLoading ? 'Loading...' : 'Submit'} |
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</button> |
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</form> |
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) |
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} |
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``` |
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### Redirecting |
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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: |
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```ts filename="pages/api/submit.ts" switcher |
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import type { NextApiRequest, NextApiResponse } from 'next' |
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export default async function handler( |
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req: NextApiRequest, |
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res: NextApiResponse |
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) { |
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const id = await addPost() |
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res.redirect(307, `/post/${id}`) |
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} |
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``` |
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```js filename="pages/api/submit.js" switcher |
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export default async function handler(req, res) { |
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const id = await addPost() |
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res.redirect(307, `/post/${id}`) |
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} |
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``` |
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