Server action in client components in NextJS - Mini Project: Build & Apply

Using Server Actions in Next.js Client Components

📖 Scenario: You are building a simple feedback form on a website. Users can type their feedback and submit it. The feedback should be sent to the server to be saved.

🎯 Goal: Create a Next.js client component that uses a server action to handle form submission and save feedback.

📋 What You'll Learn

Create a client component with a form and a textarea input named feedback.

Create a server action function called saveFeedback that accepts the feedback text.

Use the server action in the client component to handle the form submission.

Show a confirmation message after successful submission.

💡 Why This Matters

🌍 Real World

Collecting user feedback or form data on websites using Next.js with server actions for efficient server communication.

💼 Career

Understanding server actions in Next.js client components is important for building modern, scalable web applications with seamless server-client integration.

1

Create the client component with a feedback form

Create a React client component called FeedbackForm with a form containing a textarea input named feedback and a submit button. Add the directive 'use client' at the top.

NextJS

'use client'

function FeedbackForm() {
  // Your code here
}

Hint

Remember to add 'use client' at the top to make this a client component. Use a form with a textarea named feedback and a submit button.

2

Create the server action to save feedback

Create an async server action function called saveFeedback that accepts a parameter text. Inside, simulate saving by returning true. Export this function.

NextJS

'use client'

export async function saveFeedback(text) {
  // Your code here
}

export default function FeedbackForm() {
  return (
    
      
      Submit
    
  )
}

Hint

Create an async function named saveFeedback that takes text and returns true. Export it so it can be used as a server action.

3

Use the server action in the client component form

Import the saveFeedback server action into the client component. Add a form action attribute that calls saveFeedback. Use FormData to get the feedback value inside saveFeedback.

NextJS

'use client'

export async function saveFeedback(formData) {
  // Your code here
}

export default function FeedbackForm() {
  // Your code here
}

Hint

Change saveFeedback to accept formData. Use formData.get('feedback') to get the text. Set the form's action attribute to saveFeedback.

4

Show confirmation message after submission

Add a React state variable submitted initialized to false. After the server action completes, set submitted to true. Conditionally render a p tag with the text Thank you for your feedback! when submitted is true.

NextJS

'use client'

import { useState } from 'react'

export async function saveFeedback(formData) {
  const text = formData.get('feedback')
  return true
}

export default function FeedbackForm() {
  // Your code here
}

Hint

Use useState to track submission. Create a handleSubmit function that calls saveFeedback and then sets submitted to true. Show a thank you message when submitted.

Practice

1. What is the main benefit of using server actions in Next.js client components?

easy

A. They enable client components to run only on the client side without server interaction.

B. They replace the need for React hooks in client components.

C. They allow client components to run server code securely without separate API routes.

D. They automatically convert client components into server components.

Solution

1. Step 1: Understand server actions purpose

   Server actions let client components run server-side code directly, simplifying data handling.

2. Step 2: Compare with API routes

   They remove the need for separate API routes by securely running server code from client components.

3. Final Answer:

   They allow client components to run server code securely without separate API routes. -> Option C

4. Quick Check:

   Server actions simplify server code use in client components = B [OK]

Hint: Server actions run server code from client without APIs [OK]

Common Mistakes:

• Thinking server actions run only on client side
• Confusing server actions with React hooks
• Believing server actions convert client to server components

2. Which syntax correctly defines a server action in a Next.js client component?

easy

A. async function fetchData() { return await fetch('/api/data') }

B. export async function action() { 'use server'; /* server code */ }

C. function action() { 'use client'; /* client code */ }

D. const action = () => { return 'server action' }

Solution

1. Step 1: Identify server action syntax

   Server actions require the 'use server' directive inside an async function to mark server code.

2. Step 2: Check options for correct usage

   export async function action() { 'use server'; /* server code */ } correctly exports an async function with 'use server' directive, matching Next.js pattern.

3. Final Answer:

   export async function action() { 'use server'; /* server code */ } -> Option B

4. Quick Check:

   'use server' directive marks server action = A [OK]

Hint: Look for 'use server' directive inside async function [OK]

Common Mistakes:

• Missing 'use server' directive in server action
• Using 'use client' inside server action
• Defining server action as non-async function

3. Given this code in a Next.js client component, what will happen when the button is clicked?

"use client";
import { useState } from 'react';
import { serverAction } from './actions';

export default function MyComponent() {
  const [message, setMessage] = useState('');

  async function handleClick() {
    const result = await serverAction();
    setMessage(result);
  }

  return (
    <>
      Click me
      
{message}
    </>
  );
}

medium

A. The button click calls serverAction, updates message with its result, and displays it.

B. The button click causes a syntax error because serverAction cannot be called in client.

C. The message state never updates because serverAction runs only on server components.

D. The button click reloads the page instead of calling serverAction.

Solution

1. Step 1: Understand serverAction usage in client component

   The client component imports and calls serverAction asynchronously on button click.

2. Step 2: Analyze state update and rendering

   After awaiting serverAction, the result updates state 'message', which renders inside <p> tag.

3. Final Answer:

   The button click calls serverAction, updates message with its result, and displays it. -> Option A

4. Quick Check:

   Server action called and result shown = C [OK]

Hint: Server actions return data to client, update state to show result [OK]

Common Mistakes:

• Assuming serverAction cannot be called from client
• Forgetting async/await in handleClick
• Expecting page reload on button click

4. Identify the error in this Next.js client component using a server action:

"use client";
import { serverAction } from './actions';

export default function Comp() {
  function handleClick() {
    const result = serverAction();
    console.log(result);
  }

  return Run;
}

medium

A. The component must use 'use server' directive instead of 'use client'.

B. serverAction cannot be imported into client components.

C. The button element must have an aria-label for accessibility.

D. handleClick must be async and await serverAction to get the result.

Solution

1. Step 1: Check serverAction call in handleClick

   serverAction is async, so calling it without await returns a Promise, not the result.

2. Step 2: Fix handleClick to async and await

   Making handleClick async and awaiting serverAction ensures correct result is logged.

3. Final Answer:

   handleClick must be async and await serverAction to get the result. -> Option D

4. Quick Check:

   Async function must await server action = D [OK]

Hint: Always await async server actions in client handlers [OK]

Common Mistakes:

• Calling async server action without await
• Thinking serverAction can't be imported in client
• Ignoring accessibility best practices (not main error here)

5. You want to create a Next.js client component that uses a server action to submit a form and then reset the form fields. Which approach correctly combines server action usage and client state reset?

hard

A. Define an async server action with 'use server', call it in client handler with await, then reset state after await.

B. Call the server action without await, reset state immediately after calling it.

C. Use a server component instead of client component to handle form and reset state automatically.

D. Reset form state inside the server action function after processing data.

Solution

1. Step 1: Understand server action and client state interaction

   Server actions run on server; client state reset must happen after server action completes.

2. Step 2: Correct async handling and state reset

   Await server action call in client handler, then reset form state to ensure proper sequence.

3. Final Answer:

   Define an async server action with 'use server', call it in client handler with await, then reset state after await. -> Option A

4. Quick Check:

   Await server action before resetting client state = A [OK]

Hint: Await server action before resetting client form state [OK]

Common Mistakes:

• Resetting state before awaiting server action
• Trying to reset client state inside server action
• Using server component instead of client for interactive form