CS 492 Week 7 Exploration 3 Exercise Forms

main.dart

import 'package:flutter/material.dart';

void main() => runApp(App());

class App extends StatelessWidget {
 
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        debugShowCheckedModeBanner: false,
        home: Scaffold(
          appBar: AppBar(title: Text('Sign In')),
          body: NameForm()
        )
     );
  }
}

class NameForm extends StatefulWidget {
  @override
  NameFormState createState() => NameFormState();
}

class NameFormState extends State<NameForm> {

  final formKey = GlobalKey<FormState>();

  @override
  Widget build(BuildContext context) {
    return Form(
        key: formKey,
        child: Padding(
          padding: const EdgeInsets.all(20),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: formFields(context)
          )
        )
      );
  }
  
  List<Widget> formFields(BuildContext context) {
    return [
      TextFormField(
        autofocus: true,
        decoration: InputDecoration(
          labelText: 'Username',
          border: OutlineInputBorder()),
        validator: (value) => validateUsername(value),
        ),
        SizedBox(height: 20),
        TextFormField(
          autofocus: true,
          decoration: InputDecoration(
          labelText: 'Password',
          border: OutlineInputBorder()),
          // TODO: Specify the validator closure
        ),
        SizedBox(height: 10),
        RaisedButton(
          // TODO: invoke validateAndSignIn when pressed
          onPressed: () {},
          child: Text('Sign In')
        )
      ];
  }
  
  void validateAndSignIn(BuildContext context) {
    final formState = formKey.currentState;
    if (formState.validate()) {
      Scaffold.of(context).showSnackBar(
        SnackBar(content: Text('Logging you in...'))
      );
    }
  }
  
  String validateUsername(String username) {
    // TODO: Implement validation logic.
    //       Return a String (error message) or null
  }
  
  String validatePassword(String password) {
    // TODO: Implement validation logic.
    //       Return a String (error message) or null
  }
}

solution.dart

import 'package:flutter/material.dart';

void main() => runApp(App());

class App extends StatelessWidget {
 
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        debugShowCheckedModeBanner: false,
        home: Scaffold(
          appBar: AppBar(title: Text('Sign In')),
          body: NameForm()
        )
     );
  }
}

class NameForm extends StatefulWidget {
  @override
  NameFormState createState() => NameFormState();
}

class NameFormState extends State<NameForm> {

  final formKey = GlobalKey<FormState>();

  @override
  Widget build(BuildContext context) {
    return Form(
        key: formKey,
        child: Padding(
          padding: const EdgeInsets.all(20),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: formFields(context)
          )
        )
      );
  }
  
  List<Widget> formFields(BuildContext context) {
    return [
      TextFormField(
        autofocus: true,
        decoration: InputDecoration(
          labelText: 'Username',
          border: OutlineInputBorder()),
        validator: (value) => validateUsername(value),
        ),
        SizedBox(height: 20),
        TextFormField(
          autofocus: true,
          decoration: InputDecoration(
          labelText: 'Password',
          border: OutlineInputBorder()),
          // DONE
          validator: (value) => validatePassword(value)
        ),
        SizedBox(height: 10),
        RaisedButton(
          // DONE
          onPressed: () => validateAndSignIn(context),
          child: Text('Sign In')
        )
      ];
  }
  
  void validateAndSignIn(BuildContext context) {
    final formState = formKey.currentState;
    if (formState.validate()) {
      Scaffold.of(context).showSnackBar(
        SnackBar(content: Text('Logging you in...'))
      );
    }
  }
  
  String validateUsername(String username) {
    // DONE
    if (username == '') {
      return 'Username cannot be blank';
    } else return null;
  }
  
  String validatePassword(String password) {
    // DONE
    if (password == '') {
      return 'Password cannot be blank';
    } else return null;
  }
}