Extensions

Extensions are python packages that provide additional functionality or integrate external libraries into the framework.

Current builtin extensions are:

• SQLAlchemy
• Jinja

Activating extensions

Extensions need to be activated in settings.yaml, in the extensions property:

extensions:
- selva.ext.data.sqlalchemy
- selva.ext.templates.jinja

Creating extensions

An extension is a python package or module that contains a function named selva_extension with arguments selva.di.Container and selva.configuration.Settings. It is called during the startup phase of the application and may also be a coroutine.

from selva.configuration import Settings
from selva.di import Container

# (1)
def selva_extension(container: Container, settings: Settings):
    pass

1. selva_extension can also be async.

The function can then access values in the settings object, register new services, retrieve the router service to register new routes, etc.