Form validation with YUP

Simplify your Form Validation in React with Yup

When building web applications, form validation is key to ensuring data integrity. If you're looking for a simple yet powerful way to validate forms in React, Yup is your best friend! This blog will walk you through the steps to set up Yup and create a polished form with validation.

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What You’ll Learn

By the end of this blog, you'll know how to:

1. Set up Yup for validation in React.
2. Build a form with validation rules.
3. Style your form using external CSS.

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Prerequisites

Before diving in, make sure you have:

• Basic knowledge of React.
• Node.js installed on your computer.

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Step 1: Setting Up Yup

First, install Yup in your React project. Run the following command in your terminal:

npm install yup

Step 2: Creating the Form

Here's a simple form with fields for a name and email. We'll use React's useState to manage input values and errors.

import React, { useState } from 'react';

function MyForm() {
  const [formData, setFormData] = useState({ name: '', email: '' });
  const [errors, setErrors] = useState({});

  const handleChange = (e) => {
    setFormData({ ...formData, [e.target.name]: e.target.value });
  };

  const handleSubmit = (e) => {
    e.preventDefault();
    // Validation will go here
  };

  return (
    <form onSubmit={handleSubmit}>
      <div>
        <label>Name:</label>
        <input
          type="text"
          name="name"
          value={formData.name}
          onChange={handleChange}
        />
      </div>
      <div>
        <label>Email:</label>
        <input
          type="email"
          name="email"
          value={formData.email}
          onChange={handleChange}
        />
      </div>
      <button type="submit">Submit</button>
    </form>
  );
}

export default MyForm;

Step 3:

Now it is time to integrate Yup. I'll be creating a validation schema and then check the form data once submitted.

import * as Yup from "yup"

const validationSchema = Yup.object({
name: Yup.string().required('Name is required!')
email: Yup.string().email('Your email is invalid').required('email is required')
})

I'll use this schema in the handleSubmit function to validate the form

  const handleSubmit = (e) => {
    e.preventDefault();
    try {
    await validationSchema.validate(formData, { abortEarly: false });
    setErrors({});
    alert('Form is valid!');
  } catch (err) {
    const newErrors = {};
    err.inner.forEach((error) => {
      newErrors[error.path] = error.message;
    });
    setErrors(newErrors);
  }
  };

Step 4: Styling the form

To make the form look good, create an external CSS file (MyForm.css) and add these styles:

.form-container {
  max-width: 400px;
  margin: 50px auto;
  padding: 20px;
  background: #f9f9f9;
  border-radius: 8px;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}
.label {
  font-weight: bold;
}
.input {
  width: 100%;
  padding: 10px;
  margin: 5px 0;
  border-radius: 4px;
}
.error {
  color: red;
  font-size: 12px;
}
.button {
  background: #4caf50;
  color: white;
  padding: 10px;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}
.button:hover {
  background: #45a049;
}

Import the CSS file into your component:

import './MyForm.css';

Full Code:

import React, { useState } from 'react';
import * as Yup from 'yup';
import './MyForm.css';

function MyForm() {
  const [formData, setFormData] = useState({ name: '', email: '' });
  const [errors, setErrors] = useState({});

  const validationSchema = Yup.object({
    name: Yup.string().required('Name is required!'),
    email: Yup.string().email('Invalid email!').required('Email is required!'),
  });

  const handleChange = (e) => {
    setFormData({ ...formData, [e.target.name]: e.target.value });
  };

  const handleSubmit = async (e) => {
    e.preventDefault();
    try {
      await validationSchema.validate(formData, { abortEarly: false });
      setErrors({});
      alert('Form is valid!');
    } catch (err) {
      const newErrors = {};
      err.inner.forEach((error) => {
        newErrors[error.path] = error.message;
      });
      setErrors(newErrors);
    }
  };

  return (
    <div className="form-container">
      <h1>Simple Form</h1>
      <form onSubmit={handleSubmit}>
        <div>
          <label className="label">Name:</label>
          <input
            type="text"
            name="name"
            value={formData.name}
            onChange={handleChange}
            className="input"
          />
          {errors.name && <div className="error">{errors.name}</div>}
        </div>
        <div>
          <label className="label">Email:</label>
          <input
            type="email"
            name="email"
            value={formData.email}
            onChange={handleChange}
            className="input"
          />
          {errors.email && <div className="error">{errors.email}</div>}
        </div>
        <button type="submit" className="button">Submit</button>
      </form>
    </div>
  );
}

export default MyForm;

Conclusion

Yup is a powerful tool for form validation, even without Formik. With just a few lines of code, you can add robust validation to your React apps.