v6_MIGRATION_GUIDE.md

Migrating to Unleash-Client-Python 6.0.0

This guide highlights the key changes you should be aware of when upgrading to v6.0.0 of the Unleash client.

Removed direct access to feature flags

Direct access to the feature flag objects through UnleashClient.features has been removed. All classes related to the internal representation of feature flags are no longer publicly accessible in the SDK.

The SDK now provides an UnleashClient.feature_definitions() method, which returns a list of feature flag names, their type, and the project they're bound to.

Changes to custom strategies

Custom strategies have undergone some changes that require updates to their implementations. This is a strict requirement: any strategy that does not implement the correct interface will throw an exception at startup.

The interface changes are as follows:

• Strategies no longer inherit from a base class.
• The apply method now accepts a second parameter, parameters. In legacy versions, this functionality was managed by the load_provisioning() method.

Here is an example of a legacy strategy:

class CatStrategy(Strategy):
    def load_provisioning(self) -> list:
        return [x.strip() for x in self.parameters["sound"].split(",")]

    def apply(self, context: dict = None) -> bool:
        default_value = False

        if "sound" in context.keys():
            default_value = context["sound"] in self.parsed_provisioning

        return default_value

This is now written as:

class CatStrategy:
    def apply(self, parameters: dict, context: dict = None) -> bool:
        default_value = False

        parsed_parameters = [x.strip() for x in parameters["sound"].split(",")]

        if "sound" in context.keys():
            default_value = context["sound"] in parsed_parameters

        return default_value

Strategies are now mounted as an instance rather than a class object when configuring the SDK:

custom_strategies_dict = {"amIACat": CatStrategy()}

unleash_client = UnleashClient(
    "some_unleash_url", "some_app_name", custom_strategies=custom_strategies_dict
)