Fail to register blueprint

[ChenHaolinOlym]

I want to use init_app to initialize the application and I want to put all my api part of code into a separate .py file. So I do something below: interface.py:

from flask_smorest import Api
api = Api()
blp=Blueprint()
# Some settings
api.register_blueprint(blp)

__init__.py

from .interface import api
def create_app():
    app=Flask(__name__)
    api.init_app(app)

I would get an error: AttributeError: 'NoneType' object has no attribute 'register_blueprint' This is because I register blueprint before I init_app I really want to organize my code like this so can flask-smorest support this?

[lafrech]

Blueprints must be registered after app init (because the process depends on app parameters like OpenAPI version for the docs).

from flask_smorest import Api
api = Api()
blp=Blueprint()
# Some settings
def register_blueprints():
    api.register_blueprint(blp)

from .interface import api, register_blueprints
def create_app():
    app=Flask(__name__)
    api.init_app(app)
    register_blueprints()

[ChenHaolinOlym]

Thanks for your help