launchdarkly_flutter_client_sdk 4.3.0 launchdarkly_flutter_client_sdk: ^4.3.0 copied to clipboard
Official Flutter client-side SDK for LaunchDarkly. Get started using LaunchDarkly today!
import 'package:flutter/material.dart';
import 'package:launchdarkly_flutter_client_sdk/launchdarkly_flutter_client_sdk.dart';
import 'package:provider/provider.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
// The LDClient doesn't need to change throughout the lifetime of the
// application, so we wrap the application in a provider with the client.
return Provider<LDClient>(
create: (_) => LDClient(
LDConfig(
// The credentials come from the environment, you can set them
// using --dart-define.
// Examples:
// flutter run --dart-define LAUNCHDARKLY_CLIENT_SIDE_ID=<my-client-side-id> -d Chrome
// flutter run --dart-define LAUNCHDARKLY_MOBILE_KEY=<my-mobile-key> -d ios
//
// Alternatively `CredentialSource.fromEnvironment()` can be replaced with your mobile key.
CredentialSource.fromEnvironment(),
AutoEnvAttributes.enabled,
),
// Here we are using a default user with 'user-key'.
LDContextBuilder().kind('user', 'user-key').build()),
dispose: (_, client) => client.close(),
// We use a future provider to wait for the client to either start,
// or for a timeout to elapse.
child: MaterialApp(
title: 'LaunchDarkly Example',
theme: ThemeData(
colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
useMaterial3: true,
),
home: const MyHomePage(title: 'LaunchDarkly Example'),
));
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({super.key, required this.title});
final String title;
@override
State<MyHomePage> createState() => _MyHomePageState();
}
/// Example provider which listens for flag changes and maps them to string
/// values. It would also be possible to map to some application specific model
/// types. When mapping be sure all values are accessed through the client
/// `variation` methods. This ensures that the SDK generates the expected
/// events.
class FlagProviderString extends StreamProvider<String> {
FlagProviderString(
{super.key,
required LDClient client,
required String flagKey,
required String defaultValue,
required Widget child})
: super(
create: (context) => client.flagChanges
.where((element) => element.keys.contains(flagKey))
.map((event) => client.stringVariation(flagKey, defaultValue)),
// Here we get the initial value of the flag. If the SDK is not
// initialized, then the default value will be returned.
initialData: client.stringVariation(flagKey, defaultValue),
child: child);
}
class _MyHomePageState extends State<MyHomePage> {
final _userKeyController = TextEditingController(text: 'user-key');
final _formKey = GlobalKey<FormState>();
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
backgroundColor: Theme.of(context).colorScheme.inversePrimary,
title: Text(widget.title),
),
body: // The FutureBuilder here is used in order to gate the presentation content
// based on the LaunchDarkly SDK having started. While it has not started
// a loading indicator will be shown. Once it has started, or encountered
// a timeout, then it will render the content.
FutureBuilder(
future: Provider.of<LDClient>(context, listen: false)
.start()
// In this case we do not have special handling for a failed
// initialization or timeout.
.timeout(const Duration(seconds: 5), onTimeout: () => true)
.then((value) => true),
builder: (context, loaded) => loaded.data ?? false
? Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Form(
key: _formKey,
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
TextFormField(
// The validator receives the text that the user has entered.
validator: (value) {
if (value == null || value.isEmpty) {
return 'Please enter a user key';
}
return null;
},
controller: _userKeyController,
),
Padding(
padding:
const EdgeInsets.symmetric(vertical: 16),
child: ElevatedButton(
onPressed: () {
// Validate returns true if the form is valid, or false otherwise.
if (_formKey.currentState!.validate()) {
final client = Provider.of<LDClient>(
context,
listen: false);
client
.identify(LDContextBuilder()
.kind('user',
_userKeyController.text)
.build())
.then((value) {
ScaffoldMessenger.of(context)
.showSnackBar(
const SnackBar(
content:
Text('Identify complete')),
);
});
}
},
child: const Text('Identify'),
),
),
],
),
),
FlagProviderString(
// The client will not be changing, so we don't need to
// listen for client changes.
client:
Provider.of<LDClient>(context, listen: false),
flagKey: 'string-flag',
defaultValue: 'default-value',
child: Consumer<String>(
builder: (context, flagValue, _) =>
Text('flag value: $flagValue'))),
],
),
)
: const CircularProgressIndicator()),
);
}
}