sI am trying to use Flask-Migrate in my Flask project but I faced an error.
I installed Flask-Migrate and add needed code, but when I run “flask db init”, It cannot find my database models that I defined.

This is my project structure:

sample_project/
├── __init__.py
├── api.py
└── sample_models/
    ├── __init__.py
    ├── db.py
    └── sample_model.py

In my api.py:

from flask import Flask
from sample_models.db import db
from flask_migrate import Migrate

def create_app(test_config=None):
    migrate = Migrate()
    app = Flask(__name__, instance_relative_config=True)

    if test_config is None:
        # load the instance config, if it exists, when not testing
        app.config.from_object(os.environ['APP_SETTINGS'])
    else:
        # load the test config if passed in
        app.config.from_mapping(test_config)

        # ensure the instance folder exists
    try:
        os.makedirs(app.instance_path)
    except OSError:
        pass

    db.init_app(app)
    migrate.init_app(app, db)

    with app.app_context():
        db.create_all()

    @app.route('/test', methods=['POST'])
    def test():
        
        return "Flask app is running"
    return app

if __name__ == '__main__':
    app = create_app()
    app.run(debug=True, host='0.0.0.0')

In my db.py:

from flask_sqlalchemy import SQLAlchemy

db = SQLAlchemy()

In my sample_model.py:

from .db import db

class SampleModel(db.Model):
  __tablename__ = 'sample_table'

  id: Mapped[int] = mapped_column(primary_key=True)
  name: Mapped[str]
  age: Mapped[int]

When I run

flask db init

I got the error below:

Error: While importing 'app.api', an ImportError was raised:

Traceback (most recent call last):
  File "/usr/local/lib/python3.12/site-packages/flask/cli.py", line 245, in locate_app
    __import__(module_name)
  File "/app/api.py", line 5, in <module>
    from sample_models.db import db
ModuleNotFoundError: No module named 'sample_models'

Any idea?