How to Add Form Validation In Next.js ?

Last Updated : 02 Aug, 2024

Forms play a crucial role in modern web applications by ensuring the accuracy and validity of data. Next.js, a versatile framework for building React applications, offers form validation that helps verify user input against predefined criteria, provides immediate feedback, and enhances data quality. In this article, we will cover essential concepts such as required fields, data format validation, and custom error messaging.

Prerequisites:

Approach

To add form validation in next js app we are going to use useState and useEffect hooks to dynamically manage form state and validation rules.

React's useState() hook encapsulates local state variables in functional components. It is a special function that takes the initial state as an argument and returns a two-entry array. It only contains singular values and necessitates useState calls for multiple state implementations.
React's useEffect hook handles side effects such as fetching data and updating the DOM, and it runs on every render and makes use of dependency arrays.

Steps to Create the NextJS Application

Step 1: Create a new Next.js project using the following command

NPX: Package runner tool in npm 5.2+, npx, is an easy CLI for running Node packages.

npx create-next-app form-validation-app

Step 2: Change to the project directory:

cd form-validation-app

Project Structure:

Next-js-Project-Structure

Example: This example demonstrates form handling in next.js using the react hooks.

JavaScript

// Filename - App.js file   import React, { useState, useEffect } from 'react';  const App = () => {     const [name, setName] = useState('');     const [email, setEmail] = useState('');     const [password, setPassword] = useState('');     const [errors, setErrors] = useState({});     const [isFormValid, setIsFormValid] = useState(false);      useEffect(() => {         validateForm();     }, [name, email, password]);     // Validate form     const validateForm = () => {         let errors = {};          if (!name) {             errors.name = 'Name is required.';         }          if (!email) {             errors.email = 'Email is required.';         } else if (!/\S+@\S+\.\S+/.test(email)) {             errors.email = 'Email is invalid.';         }          if (!password) {             errors.password = 'Password is required.';         } else if (password.length < 6) {             errors.password = 'Password must be at least 6 characters.';         }          setErrors(errors);         setIsFormValid(Object.keys(errors).length === 0);     };     // Submit     const handleSubmit = () => {         if (isFormValid) {             console.log('Form submitted successfully!');         } else {             console.log('Form has errors. Please correct them.');         }     };      return (         <div style={styles.container}>             <div style={styles.form}>                 <h1 style={styles.heading}>                     Geeksforgeeks || Form Validation In Next.js                 </h1>                 <h3 style={styles.subHeading}>Login Page</h3>                 <input                     style={styles.input}                     placeholder="Name"                     value={name}                     onChange={(e) => setName(e.target.value)}                 />                 {errors.name && <p style={styles.error}>{errors.name}</p>}                 <input                     style={styles.input}                     placeholder="Email"                     value={email}                     onChange={(e) => setEmail(e.target.value)}                 />                 {errors.email && <p style={styles.error}>{errors.email}</p>}                 <input                     style={styles.input}                     placeholder="Password"                     value={password}                     onChange={(e) => setPassword(e.target.value)}                     type="password"                 />                 {errors.password && <p style={styles.error}>{errors.password}</p>}                 <button                     style={{ ...styles.button, opacity: isFormValid ? 1 : 0.5 }}                     disabled={!isFormValid}                     onClick={handleSubmit}                 >                     Submit                 </button>             </div>         </div>     ); };  const styles = {     container: {         display: 'flex',         alignItems: 'center',         justifyContent: 'center',         minHeight: '100vh',         backgroundColor: '#f0f0f0',     },     heading: {         fontWeight: 'bold',         fontSize: '25px',         color: "green",         textAlign: "center",     },     subHeading: {         fontWeight: 'bold',         fontSize: '25px',         textAlign: "center",      },     form: {         backgroundColor: '#fff',         padding: '20px',         borderRadius: '8px',         boxShadow: '0 2px 4px rgba(0, 0, 0, 0.1)',         width: '100%',         maxWidth: '400px',         margin: '0 auto',     },     input: {         width: '100%',         padding: '12px',         marginBottom: '12px',         border: '1px solid #ccc',         borderRadius: '10px',         fontSize: '16px',         transition: 'border-color 0.2s ease',     },     button: {         backgroundColor: 'green',         color: '#fff',         fontWeight: 'bold',         fontSize: '16px',         padding: '12px',         border: 'none',         borderRadius: '10px',         cursor: 'pointer',         width: '40%',         transition: 'opacity 0.2s ease',     },     error: {         color: 'red',         fontSize: '14px',         marginBottom: '6px',     }, };  export default App;

Step to run the application: Run the Next.js application at URL http://localhost:3000 using the below command.

npm run dev

Output:

How To Implement NextJS Form Validation With Formik And Zod ?

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Article Tags :

How to Add Form Validation In Next.js ?

Prerequisites:

Approach

Steps to Create the NextJS Application

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