This is a tiny Unleash Client SDK you can use together with the Unleash Frontend API or the Unleash Proxy. This makes it super simple to use Unleash from any Flutter app.

flutter pub add unleash_proxy_client_flutter

💡 TIP: As a client-side SDK, this SDK requires you to connect to either an Unleash proxy or to the Unleash front-end API. Refer to the connection options section for more information.

Configure the client according to your needs. The following example provides only the required options. Refer to the section on available options for the full list.

import 'package:unleash_proxy_client_flutter/unleash_proxy_client_flutter.dart';

final unleash = UnleashClient(
    url: Uri.parse('https://<your-unleash-instance>/api/frontend'),
    clientKey: '<your-client-side-token>',
    appName: 'my-app');

To connect this SDK to your Unleash instance's front-end API, use the URL to your Unleash instance's front-end API (<unleash-url>/api/frontend) as the url parameter. For the clientKey parameter, use a FRONTEND token generated from your Unleash instance. Refer to the how to create API tokens guide for the necessary steps.

To connect this SDK to the Unleash proxy, use the proxy's URL and a proxy client key. The configuration section of the Unleash proxy docs contains more info on how to configure client keys for your proxy.

You should wait for the client's ready or initialized events before you start working with it. Before it's ready, the client might not report the correct state for your features.

unleash.on('ready', (_) {
    if (unleash.isEnabled('proxy.demo')) {
      print('proxy.demo is enabled');
    } else {
      print('proxy.demo is disabled');
    }
});

The difference between the events is explained below.

Once the client is ready, you can start checking features in your application. Use the isEnabled method to check the state of any feature you want:

unleash.isEnabled('proxy.demo');

You can use the getVariant method to get the variant of an enabled feature that has variants. If the feature is disabled or if it has no variants, then you will get back the disabled variant

final variant = unleash.getVariant('proxy.demo');

if(variant.name == 'blue') {
 // something with variant blue...
}

The Unleash context is used to evaluate features against attributes of a the current user. To update and configure the Unleash context in this SDK, use the updateContext and setContextField methods.

The context you set in your app will be passed along to the Unleash proxy or the front-end API as query parameters for feature evaluation.

The updateContext method will replace the entire (mutable part) of the Unleash context with the data that you pass in.

The setContextField method only acts on the property that you choose. It does not affect any other properties of the Unleash context.

// Used to set the context fields, shared with the Unleash Proxy. This 
// method will replace the entire (mutable part) of the Unleash Context.
unleash.updateContext(UnleashContext(userId: '1233'));

// Used to update a single field on the Unleash Context.
unleash.setContextField('userId', '4141');

The Unleash SDK takes the following options:

The client is also an event emitter. This means that your code can subscribe to updates from the client. This is a neat way to update your app when toggle state updates.

unleash.on('update', (_) {
    final myToggle = unleash.isEnabled('proxy.demo');
    //do something useful
});

• error - emitted when an error occurs on init, or when fetch function fails, or when fetch receives a non-ok response object. The error object is sent as payload.
• initialized - emitted after the SDK has read local cached data in the storageProvider.
• ready - emitted after the SDK has successfully started and performed the initial fetch towards the Unleash Proxy.
• update - emitted every time the Unleash Proxy return a new feature toggle configuration. The SDK will emit this event as part of the initial fetch from the SDK.

PS! Please remember that you should always register your event listeners before your call unleash.start(). If you register them after you have started the SDK you risk loosing important events.

You may provide a custom session id via the "context". If you do not provide a sessionId this SDK will create a random session id, which will also be stored in the provided storage. By always having a consistent sessionId available ensures that even "anonymous" users will get a consistent experience when feature toggles is evaluated, in combination with a gradual (percentage based) rollout.

You can stop the Unleash client by calling the stop method. Once the client has been stopped, it will no longer check for updates or send metrics to the server.

A stopped client can be restarted.

unleash.stop();

Now it is possible to bootstrap the SDK with your own feature toggle configuration when you don't want to make an API call.

This is also useful if you require the toggles to be in a certain state immediately after initializing the SDK.

Add a bootstrap attribute when create a new UnleashClient.
There's also a bootstrapOverride attribute which is by default is true.

final unleash = UnleashClient(
    url: Uri.parse('https://app.unleash-hosted.com/demo/api/proxy'),
    clientKey: 'proxy-123',
    appName: 'my-app',
    bootstrapOverride: false,
    bootstrap: {
    'demoApp.step4': ToggleConfig(
        enabled: true,
        impressionData: false,
        variant: Variant(enabled: true, name: 'blue'))
});

NOTES: ⚠️

• If bootstrapOverride is true (by default), any local cached data will be overridden with the bootstrap specified.
• If bootstrapOverride is false any local cached data will not be overridden unless the local cache is empty.

• flutter test
• flutter format lib test
• flutter analyze lib test
• dart pub publish