Download the PHP package em411/feature-flag-bundle without Composer

FeatureFlag Bundle

The FeatureFlag Bundle allows you to split the code execution flow by enabling features depending on context.

It provides a service that checks if a feature is enabled. Each feature is defined by a callable function that returns a value. The feature is enabled if the value matches the expected one (mostly a boolean but not limited to).

This bundle code has been borrowed from https://github.com/symfony/symfony/pull/53213.

Symfony 4.4 / PHP 7.4 backport. This is a fork of ajgarlag/feature-flag-bundle refactored to run on Symfony 4.4 and PHP 7.4.

Which package should I use?

• Running Symfony 6+ / PHP 8.1+? Use the upstream ajgarlag/feature-flag-bundle — it targets modern Symfony and uses native PHP 8 attributes.
• Stuck on Symfony 4.4 / PHP 7.4? Use this fork. It exists because the upstream cannot run on legacy stacks. The public API is intentionally kept compatible with the upstream so migration is a namespace-free drop-in.

Note on the namespace. The Composer package is em411/feature-flag-bundle but the PHP namespace remains Ajgarlag\FeatureFlagBundle\ on purpose, so code written against the upstream works here unchanged. Imports and the bundle class reference (Ajgarlag\FeatureFlagBundle\FeatureFlagBundle::class) stay the same.

🚀 Getting Started

Follow these steps to install and use the bundle in your Symfony application.

Step 1: Download the bundle

Open a command console, enter your project directory and execute the following command to download the latest stable version of this bundle:

Step 2: Enable the bundle (for non-Flex applications)

Then, enable the bundle by adding it to the list of registered bundles in the config/bundles.php file of your project:

✨ Declaring features with annotations

You can declare features using the @AsFeature annotation. This allows you to autoconfigure your features as services.

On a class

You can use the annotation on an invokable class:

The feature will be named xmas. If you don't provide a name, the FQCN of the class will be used.

You can also use the method property of the annotation to specify a method to call on the service.

On a method

You can also use the annotation on a method of a service. The method must be public.

Note: Unlike PHP 8 attributes, a Doctrine annotation cannot be repeated on the same class or method. To declare multiple features on one class, use the ajgarlag.feature_flag.feature service tag.

Gating routes by a feature

Symfony 4.4 cannot evaluate services inside route condition expressions, so route-level feature gating is done in the controller (or a kernel.controller listener). Inject FeatureCheckerInterface and throw a 404 when the feature is off:

🧩 Providers

Providers are responsible for returning the feature callables. You can create your own provider by implementing the ProviderInterface.

Any service that implements ProviderInterface is automatically registered as a provider. The bundle comes with a ChainProvider that allows you to combine multiple providers. The first provider that returns a feature wins.

The ProviderInterface

To create your own provider, you need to implement the ProviderInterface.

The get method must return a callable if the provider has the feature, or null otherwise.

Priority

You can control the order of the providers in the chain using the priority attribute of the ajgarlag.feature_flag.provider tag.

Set the priority on the service tag in your configuration:

Providers with a higher priority will be checked first.

🎨 Twig extension

The bundle provides two functions to use in Twig templates: feature_is_enabled and feature_get_value.