Permit flask application factory pattern

.gitignore

@@ -9,4 +9,5 @@ dist/
 .coverage
 htmlcov/
 coverage.xml
-lcov.info
+lcov.info
+.idea/

README.md

@@ -78,6 +78,45 @@ def protected():
     pass
 ```
 
+If you're using the **Flask Application Factory**, set up using `init_app()` like:
+
+```python
+# __init__.py
+
+oauth2 = OAuth2Decorator()
+
+
+def create_app(config_class=Config):
+    application = Flask(__name__)
+    application.config.from_object(config_class)
+
+    # ... register blueprints etc
+
+    with application.app_context():
+        oauth2.init_app(application) # <-- call init_app()
+        return application
+```
+
+```python
+# some-blueprint-file.py
+
+from api import oauth2  # <-- from __init__.py
+
+bp = Blueprint('users', __name__, url_prefix=Config.ROOT_URL+ '/api/v1')
+
+
+@oauth2.requires_token()
+@bp.route('/users', methods=['GET'])
+def index():
+    """
+    Get all users
+    """
+    users = User.query.all()
+    return users_schema.dump(users)
+
+```
+
+
 # License
 
     MIT License

setup.py

@@ -5,7 +5,7 @@
 
 setup(
     name='flask-oauth2-validation',
-    version='0.1.3',
+    version='0.1.4',
     author='Henrik Sachse',
     author_email='henrik@0x7d7b.net',
     description=(

src/flask_oauth2_validation/decorator.py

@@ -49,7 +49,7 @@ class OAuth2Decorator():
 
     """
 
-    def __init__(self, app: Flask):
+    def __init__(self, app: Flask | None = None):
         """ Reads the app configuration and requests
         the Authorization Server Metadata as well as the
         authorization servers public keys.
@@ -68,12 +68,6 @@ def __init__(self, app: Flask):
 
         self._logger = logging.getLogger(__name__)
 
-        app.config.setdefault('OAUTH2_ISSUER', None)
-        app.config.setdefault('OAUTH2_AUDIENCE', None)
-        app.config.setdefault('OAUTH2_JWKS_UPDATE_INTERVAL', None)
-        app.config.setdefault('OAUTH2_CLIENT_ID', None)
-        app.config.setdefault('OAUTH2_CLIENT_SECRET', None)
-
         # Holds the current requests token in case
         # the verification steps where all successful.
         self.token = None
@@ -97,6 +91,17 @@ def __init__(self, app: Flask):
         # that's why we cache its response, here.
         self._cached_metadata = None
 
+        if app is not None:
+            self.init_app(app)
+
+    def init_app(self, app: Flask):
+
+        app.config.setdefault('OAUTH2_ISSUER', None)
+        app.config.setdefault('OAUTH2_AUDIENCE', None)
+        app.config.setdefault('OAUTH2_JWKS_UPDATE_INTERVAL', None)
+        app.config.setdefault('OAUTH2_CLIENT_ID', None)
+        app.config.setdefault('OAUTH2_CLIENT_SECRET', None)
+
         # The only mandatory value is the issuer URI.
         # In case it is the only value we expect it to offer
         # Authorization Server Metadata support (RFC-8414).

tests/functional/test_config.py

@@ -125,3 +125,11 @@ def test_introspection_setup_without_secret(test_app):
     with pytest.raises(TypeError) as err:
         OAuth2Decorator(test_app)
     assert str(err.value) == 'OAUTH2_CLIENT_SECRET config property required'
+
+
+def test_set_up_using_flask_application_factory(test_app):
+    test_app.config['OAUTH2_ISSUER'] = 'https://issuer.local/oauth2'
+    oauth2 = OAuth2Decorator()
+    oauth2.init_app(test_app)
+    assert oauth2._issuer == 'https://issuer.local/oauth2'
+    assert oauth2._jwks_uri == 'https://issuer.local/oauth2/keys'