Udapte data from db on the fly

Dash Python
1

I’m in the same situation as this post.
I’m trying to implement the option 1 proposed by chriddyp. But I can’t figure out how to do “set the data on page load and pass it through to different callbacks with hidden divs”.

Here is what I have implemented but I’m not sure where I’m going.
I did turn my app.layout into a function and I’d like to know how to set the data on page load. I understand that I should do it in a hidden div but I don’t get what could by the Input.

def serve_layout():
    return html.Div(children=[
        dcc.Graph(id='graph1'),
        dcc.Interval(
            id='refresh-data',
            interval=1000
        ),

        html.Div(id='intermediate-data', style={'display': 'none'})
    ])


app.layout = serve_layout


@app.callback(
    Output('intermediate-data', 'children'),
    [Input(....)]
)
def load_data(....):
    data = MyDB.query.filter_by(...)
    data_values = pd.DataFrame([(d.col1, d.col2) for d in data], columns=['col1', 'col2'])
    return data_values

Can you help me? Thanks