Validating email addresses is a fundamental task in app development to ensure that users provide correctly formatted and potentially valid email addresses. In Flutter, there are various methods to achieve email validation, ranging from using regular expressions to leveraging external packages. This guide will cover different ways to validate email addresses in a Flutter application.

Introduction

Email validation helps ensure that the user input is in the correct format, which is essential for data integrity and user experience. Although Flutter does not offer built-in email validation functions, developers can use several techniques to validate email addresses effectively.

Regex-Based Validation

Regular expressions (regex) provide a powerful way to match patterns in strings. You can use regex to validate email addresses in Flutter as follows:

bool validateEmail(String email) {
  String pattern =
      r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}$';
  RegExp regex = RegExp(pattern);
  return regex.hasMatch(email);
}

Usage

void main() {
  String email = 'test@example.com';
  print(validateEmail(email)); // Output: true or false
}

Using the validators Package

The validators package offers a variety of validation utilities, including email validation. To use this package, add it to your pubspec.yaml file:

dependencies:
  validators: ^2.0.1

Implementation

import 'package:validators/validators.dart' as validator;

bool validateEmail(String email) {
  return validator.isEmail(email);
}

Usage

void main() {
  String email = 'test@example.com';
  print(validateEmail(email)); // Output: true or false
}

Using the email_validator Package

The email_validator package is specifically designed for email validation. To use it, add it to your pubspec.yaml file:

dependencies:
  email_validator: '^2.1.16'

Implementation

import 'package:email_validator/email_validator.dart';

bool validateEmail(String email) {
  return EmailValidator.validate(email);
}

Usage

void main() {
  String email = 'test@example.com';
  print(validateEmail(email)); // Output: true or false
}

Custom Email Validation

For more customised email validation, combine multiple checks, such as checking the domain or using an API to verify the existence of the email address. Here’s an example of combining a basic regex check with a custom domain check:

bool validateEmail(String email) {
  String pattern =
      r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}$';
  RegExp regex = RegExp(pattern);
  if (!regex.hasMatch(email)) {
    return false;
  }
  // Custom domain validation
  List<String> validDomains = ['example.com', 'domain.com'];
  String domain = email.split('@').last;
  return validDomains.contains(domain);
}

Usage

void main() {
  String email = 'test@example.com';
  print(validateEmail(email)); // Output: true or false
}

Happy Coding and had a great weekend!