index.py

import dash
import dash_bootstrap_components as dbc
import flask

server = flask.Flask(__name__)
app = dash.Dash(external_stylesheets=[dbc.themes.BOOTSTRAP], server=server,use_pages=True)
app.config.suppress_callback_exceptions = True
# app.config['SQLALCHEMY_DATABASE_URI'] = os.environ["DATABASE_URL"]

# app = dash.Dash(__name__, use_pages=True, external_stylesheets=[dbc.themes.BOOTSTRAP])
# app.config["SESSION_PERMANENT"] = False
# app.config["SESSION_TYPE"] = "filesystem"
# app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False

# app.config["SESSION_PERMANENT"] = False
# app.config["SESSION_TYPE"] = "filesystem"
# app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False


navbar = dbc.NavbarSimple(
    dbc.DropdownMenu(
        [
            dbc.DropdownMenuItem(page["name"], href=page["path"])
            for page in dash.page_registry.values()
            if page["module"] != "pages.not_found_404"
        ],
        nav=True,
        label="More Pages",
    ),
    brand="Multi Page App Demo",
    color="primary",
    dark=True,
    className="mb-2",
)

app.layout = dbc.Container(
    [navbar, dash.page_container],
    fluid=True,
)

if __name__ == "__main__":
    app.run_server(debug=True)