Improve validation

In this step, we're going to

  • Improve email validation by using package
  • Fix confirm password validation

Improve email validation

First, let's improve email validation by using library.

Install https://pub.dev/packages/email_validator

pubspec.yaml
...
dependencies:
flutter:
sdk: flutter
# The following adds the Cupertino Icons font to your application.
# Use with the CupertinoIcons class for iOS style icons.
cupertino_icons: ^0.1.2
email_validator: '^1.0.0'
...

Edit email field validator

import 'package:email_validator/email_validator.dart';
...
TextFormField(
controller: _emailController,
decoration: InputDecoration(labelText: 'Email', hintText: "johnjackson@example.com"),
keyboardType: TextInputType.emailAddress,
validator: (value) {
if (value.isEmpty) {
return 'Please enter email';
} else if (!EmailValidator.validate(value)) {
// Use plugin https://pub.dev/packages/email_validator
// If you don't want to use plugin https://stackoverflow.com/questions/16800540/validate-email-address-in-dart
return 'Please enter valid email';
}
return null;
},
),

Fix confirm password validation

So, next let's fix confirm password field's validation.

TextFormField(
decoration: InputDecoration(labelText: 'Confirm Password'),
controller: _confirmPasswordController,
obscureText: true,
validator: (value) {
// https://stackoverflow.com/questions/50155348/how-to-validate-a-form-field-based-on-the-value-of-the-other
if (value != _passwordController.text) {
return 'Password is not matching';
}
return null;
},
),
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