at_client_mobile 3.2.3

A Flutter extension to the at_client library which adds support for mobile, desktop and IoT devices.

example/EXAMPLE.md

at_client_mobile Example

In this example, Let us see how to use get(), put(), and delete() methods in real-time applications.

NOTE: Make sure you have read the documentation to understand the example.

Get Started

Create a new at_app using at_app package.

Generate a new at_app

at_app create --sample=<package ID> -n=<YOUR NAME SPACE> <APP NAME>

There are 2 more arguments called root-domain (-r) and api-key (-k) which are currently not required. For more details head over to at_app Flags documentation.

What will be this doing?

• This command will generate a simple skeleton of your at_app.
• Go to the .env file and add your namespace if you haven't passed it as an argument.

Run your project

flutter run

Start Coding

By default, there will be at_onboarding_flutter widget implemented in your project. But, we need to make little changes to it.

Login Screen

• Select the whole Scaffold widget (including body) and hit Ctrl + .(Windows/Linux) or ⌘ + .(Mac) and select Extract Widget.
• Name that widget LoginScreen and hit Enter.
• Now, you will see a new widget called LoginScreen in your project.
• Now let us add some properties values to onboarding widget.

NOTE : If you using VisualStudio Code, You will be catching an Exception called AtSign not found. This is because, Uncaught Exceptions is checked by default. Ignore this line in debug console - I/flutter (20332): SEVERE|2021-12-20 19:21:25.593804|AtClientService|Atsign not found

AtClientPreference? atClientPreference;
String? atSign;
/// Login Screen
Widget build(context){
/// ... other widgets ... ///
  Onboarding(
    context: context,
    atClientPreference: atClientPreference!,
    domain: AtEnv.rootDomain,
    appColor: const Color(0xFFF05E3E),
    onboard: (Map<String?, AtClientService> value, String? atsign) {
      atSign = atsign;
      _logger.finer('Successfully onboarded $atsign');
    },
    onError: (Object? error) {
      _logger.severe('Onboarding throws $error error');
    },
    nextScreen: HomeScreen(),
    appAPIKey: AtEnv.appApiKey,
    rootEnvironment: AtEnv.rootEnvironment,
  );
  /// ... ///
}

• Now let's write some app logic. Create a class with instance called ClientSdkService.

class ClientSdkService {
  static final ClientSdkService _singleton = ClientSdkService._internal();

  ClientSdkService._internal();

  factory ClientSdkService.getInstance() {
    return _singleton;
  }
}

• Get necessary instances and variables in ClientSdkService class.

static final KeyChainManager _keyChainManager = KeyChainManager.getInstance();
final AtClientManager atClientInstance = AtClientManager.getInstance();
AtClientService? atClientServiceInstance;
Map<String?, AtClientService> atClientServiceMap = <String?, AtClientService>{};
String? atsign;
AtClient? _getAtClientForAtsign() => atClientInstance.atClient;

• Write a function to get AtClient preferences.

import 'package:path_provider/path_provider.dart' as path_provider;

Future<AtClientPreference> getAtClientPreference({String? cramSecret}) async {
  Directory appDocumentDirectory =
      await path_provider.getApplicationSupportDirectory();
  return AtClientPreference()
    ..isLocalStoreRequired = true
    ..commitLogPath = appDocumentDirectory.path
    ..cramSecret = cramSecret
    ..namespace = AtEnv.namespace
    ..rootDomain = AtEnv.rootDomain
    ..hiveStoragePath = appDocumentDirectory.path;
}

• Write a get() function to get the value of the key.

Future<String?> get(AtKey atKey) async {
  try {
    AtValue? result = await _getAtClientForAtsign()!.get(atKey);
    return result.value;
  } on AtClientException catch (atClientExcep) {
    _logger.severe('❌ AtClientException : ${atClientExcep.errorMessage}');
    return null;
  } catch (e) {
    _logger.severe('❌ Exception : ${e.toString()}');
    return null;
  }
}

• Write a put() function to put the value of the key.

Future<bool> put(AtKey atKey, String value) async {
  try {
    return _getAtClientForAtsign()!.put(atKey, value);
  } on AtClientException catch (atClientExcep) {
    _logger.severe('❌ AtClientException : ${atClientExcep.errorMessage}');
    return false;
  } catch (e) {
    _logger.severe('❌ Exception : ${e.toString()}');
    return false;
  }
}

• Write a delete() function to delete the value of the key.

Future<bool> delete(AtKey atKey) async {
  try {
    return _getAtClientForAtsign()!.delete(atKey);
  } on AtClientException catch (atClientExcep) {
    _logger.severe('❌ AtClientException : ${atClientExcep.errorMessage}');
    return false;
  } catch (e) {
    _logger.severe('❌ Exception : ${e.toString()}');
    return false;
  }
}

• Fetches the atSign from the keychain.

Future<String?> getAtSign() async => _keyChainManager.getAtSign();

• After the ClientSdkService is initialized, it will be used in the onboard function.

Onboarding(
  context: context,
  atClientPreference: atClientPreference!,
  domain: AtEnv.rootDomain,
  appColor: const Color(0xFFF05E3E),
  onboard:
      (Map<String?, AtClientService> value, String? atsign) {
    atSign = atsign;
    clientSDKInstance.atsign = atsign!;
    clientSDKInstance.atClientServiceMap = value;
    clientSDKInstance.atClientServiceInstance = value[atsign];
    _logger.finer('Successfully onboarded $atsign');
  },
  onError: (Object? error) {
    _logger.severe('Onboarding throws $error error');
  },
  nextScreen: const HomeScreen(),
  appAPIKey: AtEnv.appApiKey,
  rootEnvironment: AtEnv.rootEnvironment,
);

• Your onboarding function is ready to go. Now, let's add HomeScreen widget.

class HomeScreen extends StatelessWidget {
  static const String id = 'HomeScreen';
  const HomeScreen({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    /// Get the AtClientManager instance
    var atClientManager = AtClientManager.getInstance();

    return Scaffold(
      appBar: AppBar(
        title: const Text('Dashboard'),
      ),
      body: Center(
        child: Column(
          children: [
            const Text(
                'Successfully onboarded and navigated to FirstAppScreen'),

            /// Use the AtClientManager instance to get the current atsign
            Text('Current atSign: ${atClientManager.atClient.getCurrentAtSign()}'),
          ],
        ),
      ),
    );
  }
}

• Let us edit the HomeScreen widget.

• Add a card with 2 TextFields and a button to put/update values.

final ClientSdkService _clientSdkService = ClientSdkService.getInstance();
String? atSign, _key, _value;
// ...
// ...
// ...
Card(
  shape: RoundedRectangleBorder(
    borderRadius: BorderRadius.circular(15.0),
  ),
  color: Colors.white,
  elevation: 10,
  child: Column(
    children: [
      ListTile(
        title: const Text(
          'Update ',
          style: TextStyle(
            color: Colors.black,
            fontWeight: FontWeight.bold,
            fontSize: 20.0,
          ),
        ),
        subtitle: ListView(
          shrinkWrap: true,
          children: <Widget>[
            TextField(
              decoration:
                  const InputDecoration(hintText: 'Enter Key'),
              onChanged: (String key) {
                _key = key;
              },
            ),
            TextField(
              decoration: const InputDecoration(
                hintText: 'Enter Value',
              ),
              onChanged: (String value) {
                _value = value;
              },
            ),
          ],
        ),
      ),
      Container(
        width: 150,
        margin: const EdgeInsets.all(10),
        child: TextButton(
          child: const Text(
            'Update',
            style: TextStyle(
              color: Colors.white,
            ),
          ),
          style: TextButton.styleFrom(
            backgroundColor: Theme.of(context).primaryColor,
          ),
          onPressed: () async {
            // Check if the key and value are not null
            if (_key != null && _value != null) {
              // Put the key in the AtKey
              AtKey pair = AtKey()
                ..key = _key
                ..sharedWith = atSign;
              // Call the put function that we 
              // wrote in `ClientSdkService` using it's instance.
              bool _put =
                  await _clientSdkService.put(pair, _value!);
              // Capture 
              ScaffoldMessenger.of(context).showSnackBar(
                SnackBar(
                  content: Text(
                    '${pair.key} value ${_put ? 'updated' : 'not updated'}',
                    textAlign: TextAlign.center,
                  ),
                ),
              );
            }
          },
        ),
      ),
    ],
  ),
),

• Now let us add a card to look up the updated values.

final TextEditingController? _lookupTextFieldController =
    TextEditingController();
String? _lookupKey, _lookupValue;
// ...
// ...
// ...
Card(
  shape: RoundedRectangleBorder(
    borderRadius: BorderRadius.circular(15.0),
  ),
  color: Colors.white,
  elevation: 10,
  child: Column(
    mainAxisSize: MainAxisSize.min,
    children: <Widget>[
      ListTile(
        title: const Text(
          'Scan',
          style: TextStyle(
            color: Colors.black,
            fontWeight: FontWeight.bold,
            fontSize: 20.0,
          ),
        ),
        subtitle: DropdownButton<String>(
          hint: const Text('Select Key'),
          items: _scanItems.map((String? key) {
            return DropdownMenuItem<String>(
              value: key, //key != null ? key : null,
              child: Text(key!),
            );
          }).toList(),
          onChanged: (String? value) {
            setState(() {
              _lookupKey = value;
              _lookupTextFieldController?.text = value!;
            });
          },
          value: _scanItems.isNotEmpty
              ? _lookupTextFieldController!.text.isEmpty
                  ? _scanItems[0]
                  : _lookupTextFieldController?.text
              : '',
        ),
      ),
      Container(
        width: 150,
        margin: const EdgeInsets.all(15),
        child: TextButton(
          child: const Text(
            'Scan',
            style: TextStyle(
              color: Colors.white,
            ),
          ),
          style: TextButton.styleFrom(
            backgroundColor: Theme.of(context).primaryColor,
          ),
          onPressed: () async {
            // To get the List of AtKeys, call the getAtKeys function.
            List<AtKey> response =
                await _clientSdkService.getAtKeys(
              sharedBy: atSign,
            );
            if (response.isNotEmpty) {
              // If AtKeys are not empty, get the value of the selected key
              List<String?> scanList =
                  response.map((AtKey atKey) => atKey.key).toList();
              setState(() => _scanItems = scanList);
            }
            ScaffoldMessenger.of(context).showSnackBar(
              const SnackBar(
                content: Text(
                  'Scanning keys and values done.',
                  textAlign: TextAlign.center,
                ),
              ),
            );
          },
        ),
      ),
    ],
  ),
),

• Now let us add a card to look up the values of the keys.

Card(
  shape: RoundedRectangleBorder(
    borderRadius: BorderRadius.circular(15.0),
  ),
  color: Colors.white,
  elevation: 10,
  child: Column(
    mainAxisSize: MainAxisSize.min,
    children: <Widget>[
      ListTile(
        title: const Text(
          'LookUp',
          style: TextStyle(
            color: Colors.black,
            fontWeight: FontWeight.bold,
            fontSize: 20.0,
          ),
        ),
        subtitle: Column(
          mainAxisAlignment: MainAxisAlignment.start,
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            TextField(
              decoration:
                  const InputDecoration(hintText: 'Enter Key'),
              controller: _lookupTextFieldController,
            ),
            const SizedBox(height: 20),
            const Text(
              'Lookup Result : ',
              style: TextStyle(
                fontSize: 20,
                fontWeight: FontWeight.bold,
              ),
            ),
            const SizedBox(height: 20),
            Text(
              _lookupValue ?? '',
              style: const TextStyle(
                color: Colors.teal,
                fontSize: 15,
                fontWeight: FontWeight.bold,
              ),
            ),
          ],
        ),
      ),
      Container(
        margin: const EdgeInsets.all(10),
        child: TextButton(
          child: const Text(
            'Lookup',
            style: TextStyle(
              color: Colors.white,
            ),
          ),
          style: TextButton.styleFrom(
            backgroundColor: Theme.of(context).primaryColor,
          ),
          onPressed: () async {
            // This lookup key depends on the above look up drop down
            // Handle it, if it is null.
            if (_lookupKey == null) {
              setState(() => _lookupValue = 'The key is empty.');
            } else {
              // Else fetch necessary data from the AtKey
              AtKey lookup = AtKey();
              lookup.key = _lookupKey;
              lookup.sharedWith = atSign;
              // Call the get function to get the value of the key.
              String? response =
                  await _clientSdkService.get(lookup);
              setState(() => _lookupValue = response);
            }
          },
        ),
      ),
    ],
  ),
),

• Now let us implement logout functionality. Let us write an IconButton in AppBar to make it simple.

// ClientSDKService class
Future<void> logout(BuildContext context) async {
  // Get the current atsign and Detele it from the key chain
  String? atsign = atClientInstance.atClient.getCurrentAtSign();
  await _keyChainManager.deleteAtSignFromKeychain(atsign!);
  // Reset the values of necessary variables to initial state.
  atClientServiceInstance = null;
  atClientServiceMap = <String?, AtClientService>{};
  atsign = null;
  // Pop out the current screen.
  // Pop only works on the topmost screen.(If you have used push).
  Navigator.pop(context);  
}

// HomeScreen
AppBar(
  title: const Text('Dashboard'),
  actions: [
    IconButton(
      // Call the logout function
      onPressed: () => _clientSdkService.logout(context),
      icon: const Icon(Icons.logout),
    ),
  ],
),