python flask-restx - how to avoid creating different models for post and get

Question

I am trying to rest server with python flask-restx module. My table has two columns id and value. id column is a auto-increment primary key. so for post I don't need to pass id but for get I need show it in the response.

1. Is there any way I can avoid creating two tables?
2. Is there any way I can directly map sqlalchamy model to flask-restx model.
3. how to handle sqlalchamy session object. for now, I am creating this object for each method. is is a good idea to have a global session object, how can I attach that to my flask session object?

Following is the way I am doing it.

app = Flask(__name__)
api = Api(app)

demo_api_intake_model = api.model(
    'demo_intake',
    {
        "value": fields.String(required=True, description="value")
    }
)

demo_api_output_model = api.model(
    'demo_output',
    {
        "id": fields.Integer(required=True, description="unique identifier, primary key"),
        "value": fields.String(required=True, description="value")
    }
)


@api.route("/demo")
class Demo(Resource):

    @api.marshal_list_with(demo_api_output_model, code=200)
    def get(self):
        return get_session().query(DemoModel).all()

    @api.expect(demo_api_intake_model)
    def post(self):
        json_data = request.get_json()
        demo_model = DemoModel(value=json_data.get("value"))
        session = get_session()
        session.add(demo_model)
        session.commit()
        return demo_model.id

database.py

def _create_database_connection(db_user, db_pass, db_name, instance_connection_name):


    pool = sqlalchemy.create_engine(
   
        sqlalchemy.engine.url.URL.create(
            drivername="mysql+pymysql",
            username=db_user,  # e.g. "my-database-user"
            password=my_pass,  # e.g. "my-database-password"
            database=db_name,  # e.g. "my-database-name"
            host="10.10.10.21",  # e.g. "127.0.0.1"
            port=3306,  # e.g. 3306
        ),
        # **db_config
    )

    Session = sessionmaker(bind=pool)
    session = Session()
    return session
    
def get_session():
    connection = _create_database_connection(db_user="admin", db_pass=os.getenv("db_pass"),db_name=os.getenv("db_name))
    return connection