Form Validation Example

This example demonstrates how to create a form with validation using TextFormField and GlobalKey.

dartCopy codeimport 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Form Validation',
      theme: ThemeData(primarySwatch: Colors.blue),
      home: RegistrationForm(),
    );
  }
}

class RegistrationForm extends StatefulWidget {
  @override
  _RegistrationFormState createState() => _RegistrationFormState();
}

class _RegistrationFormState extends State<RegistrationForm> {
  final _formKey = GlobalKey<FormState>();
  String? _name;
  String? _email;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Registration Form')),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Form(
          key: _formKey,
          child: Column(
            children: [
              TextFormField(
                decoration: InputDecoration(labelText: 'Name'),
                validator: (value) {
                  if (value == null || value.isEmpty) {
                    return 'Please enter your name';
                  }
                  return null;
                },
                onSaved: (value) => _name = value,
              ),
              TextFormField(
                decoration: InputDecoration(labelText: 'Email'),
                validator: (value) {
                  if (value == null || value.isEmpty) {
                    return 'Please enter your email';
                  } else if (!RegExp(r'^[^@]+@[^@]+\.[^@]+').hasMatch(value)) {
                    return 'Please enter a valid email';
                  }
                  return null;
                },
                onSaved: (value) => _email = value,
              ),
              SizedBox(height: 20),
              ElevatedButton(
                onPressed: () {
                  if (_formKey.currentState!.validate()) {
                    _formKey.currentState!.save();
                    // Process the data
                    ScaffoldMessenger.of(context).showSnackBar(
                      SnackBar(content: Text('Name: $_name, Email: $_email')),
                    );
                  }
                },
                child: Text('Submit'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}