Revalidation after mutation in NextJS

Introduction

Revalidation after mutation helps keep your website data fresh by updating the page after you change something.

When you update data on the server and want the page to show the latest info.

After submitting a form that changes content, like adding a comment.

When deleting or editing items and you want the page to refresh automatically.

To avoid showing outdated data after a user action.

When using Next.js with static or cached pages that need to update after changes.

Syntax

NextJS

'use client';
import { useRouter } from 'next/navigation';

export default function Component() {
  const router = useRouter();

  // After mutation
  router.refresh();
}

router.refresh() tells Next.js to reload the current page data.

This works well with Next.js App Router and client components.

Examples

This example updates data via API and then refreshes the page to show new data.

NextJS

'use client';
import { useRouter } from 'next/navigation';

export default function Page() {
  const router = useRouter();

  async function handleUpdate() {
    await fetch('/api/update', { method: 'POST' });
    router.refresh();
  }

  return <button onClick={handleUpdate}>Update Data</button>;
}

After deleting an item, the page refreshes to remove it from the list.

NextJS

'use client';
import { useRouter } from 'next/navigation';

export default function DeleteButton({ id }) {
  const router = useRouter();

  async function handleDelete() {
    await fetch(`/api/delete/${id}`, { method: 'DELETE' });
    router.refresh();
  }

  return <button onClick={handleDelete}>Delete Item</button>;
}

Sample Program

This form sends a new comment to the server. After sending, it refreshes the page to show the new comment without needing a manual reload.

NextJS

'use client';
import { useRouter } from 'next/navigation';

export default function CommentForm() {
  const router = useRouter();

  async function submitComment(event) {
    event.preventDefault();
    const formData = new FormData(event.target);
    await fetch('/api/comments', {
      method: 'POST',
      body: JSON.stringify({ text: formData.get('comment') }),
      headers: { 'Content-Type': 'application/json' },
    });
    router.refresh();
  }

  return (
    <form onSubmit={submitComment} aria-label="Add comment form">
      <label htmlFor="comment">Comment:</label>
      <input id="comment" name="comment" required />
      <button type="submit">Add Comment</button>
    </form>
  );
}

Important Notes

Use router.refresh() only after the mutation completes successfully.

This method reloads the current route's data but keeps the UI state intact.

It works best with Next.js App Router and client components.

Summary

Revalidation after mutation updates page data after changes.

Use router.refresh() to reload data in Next.js App Router.

This keeps your UI showing fresh, accurate information automatically.

Practice

1. What is the main purpose of revalidation after mutation in Next.js App Router?

easy

A. To update the page data after a change so the UI shows fresh information

B. To prevent any data changes from being saved

C. To reload the entire website from scratch

D. To disable user interactions temporarily

Solution

1. Step 1: Understand mutation effect

   When data changes (mutation), the UI might show old data if not updated.

2. Step 2: Purpose of revalidation

   Revalidation reloads or refreshes data so the UI reflects the latest changes.

3. Final Answer:

   To update the page data after a change so the UI shows fresh information -> Option A

4. Quick Check:

   Revalidation updates data = A [OK]

Hint: Revalidation means refreshing data after changes [OK]

Common Mistakes:

• Thinking revalidation stops data saving
• Confusing revalidation with full page reload
• Believing it disables user actions

2. Which Next.js App Router method is used to trigger revalidation after a mutation?

easy

A. router.replace()

B. router.reload()

C. router.push()

D. router.refresh()

Solution

1. Step 1: Identify method for revalidation

   Next.js App Router provides router.refresh() to reload data without full page reload.

2. Step 2: Differentiate from other methods

   router.reload() reloads whole page, router.push() and router.replace() change routes.

3. Final Answer:

   router.refresh() -> Option D

4. Quick Check:

   Revalidation uses router.refresh() = A [OK]

Hint: Use router.refresh() to reload data after mutation [OK]

Common Mistakes:

• Using router.reload() which reloads full page
• Confusing route navigation methods with revalidation
• Trying to use router.replace() for data refresh

3. Given this code snippet in a Next.js component:

import { useRouter } from 'next/navigation';

export default function UpdateButton() {
  const router = useRouter();

  async function handleClick() {
    await fetch('/api/update', { method: 'POST' });
    router.refresh();
  }

  return Update;
}

What happens when the button is clicked?

medium

A. The API is called, then the page data refreshes without full reload

B. Nothing happens because router.refresh() is incorrect

C. The page reloads completely, losing state

D. The button click causes a navigation to /api/update

Solution

1. Step 1: Analyze handleClick function

   It calls the API with POST, then calls router.refresh() to reload data.

2. Step 2: Understand router.refresh() effect

   This refreshes the current route's data without a full page reload or navigation.

3. Final Answer:

   The API is called, then the page data refreshes without full reload -> Option A

4. Quick Check:

   API call + router.refresh() updates data = C [OK]

Hint: router.refresh() updates data without full reload [OK]

Common Mistakes:

• Thinking router.refresh() reloads entire page
• Assuming router.refresh() navigates to API route
• Believing nothing happens due to syntax error

4. Identify the error in this Next.js code snippet that tries to revalidate after mutation:

import { useRouter } from 'next/navigation';

export default function DeleteButton() {
  const router = useRouter;

  async function handleDelete() {
    await fetch('/api/delete', { method: 'DELETE' });
    router.refresh();
  }

  return Delete;
}

medium

A. Button onClick should be onSubmit

B. fetch method DELETE is invalid in Next.js

C. router is not called as a function, so router.refresh() fails

D. handleDelete should not be async

Solution

1. Step 1: Check router initialization

   Code uses const router = useRouter; missing parentheses, so router is a function reference, not the router object.

2. Step 2: Effect on router.refresh()

   Calling router.refresh() fails because router is not an object but a function reference.

3. Final Answer:

   router is not called as a function, so router.refresh() fails -> Option C

4. Quick Check:

   useRouter missing () causes error = D [OK]

Hint: Always call useRouter() with parentheses [OK]

Common Mistakes:

• Forgetting parentheses on useRouter()
• Thinking DELETE method is invalid
• Confusing onClick with onSubmit

5. You have a Next.js page showing a list of items fetched from the server. After adding a new item via a mutation API call, you want the list to update automatically. Which approach correctly ensures the list refreshes with the new data without a full page reload?

hard

A. Call router.push('/current-page') after mutation to reload the page

B. Call router.refresh() after mutation to revalidate and update data

C. Reload the browser window with window.location.reload()

D. Do nothing; the list updates automatically without any code

Solution

1. Step 1: Understand goal

   After mutation, the UI must show updated list without full reload or navigation.

2. Step 2: Evaluate options

   router.push('/current-page') navigates and reloads route, window.location.reload() reloads full page, and doing nothing won't update data.

3. Step 3: Correct method

   router.refresh() triggers Next.js to revalidate data and update UI efficiently.

4. Final Answer:

   Call router.refresh() after mutation to revalidate and update data -> Option B

5. Quick Check:

   Use router.refresh() to update data after mutation = B [OK]

Hint: Use router.refresh() to update data without full reload [OK]

Common Mistakes:

• Using router.push() causing unnecessary navigation
• Reloading full page losing state
• Assuming UI updates automatically without refresh