How to save plotly dash Input as global variable

Question

I am creating a dashboard using Plotly Dash that requires data to be filtered by date (sliders don't work since some charts are categorical).

I would like to allow the user to input a date which I would then use as a global variable. I import this global variable to filter my dataframes in other python files, and then create the charts. My attempt below doesn't work; the variable start_date does not update.

app = dash.Dash()

app.layout = html.Div([
    dcc.Input(id='date', value='start date (yyyy-mm-dd)', type='text'),
    html.Button(id='submit-button', type='submit', children='Submit'),
    html.Div(id='output_div')
])

start_date = 0

@app.callback(Output('output_div', 'children'),
                [Input('submit-button', 'n_clicks')],
                [State('date', 'value')],
                )
def update_output(clicks, input_value):
    if clicks:
        print(clicks, input_value)
        global start_date
        start_date = datetime.strptime(input_value, '%Y-%m-%d').date()
        return start_date
        print(type(start_date))


if __name__ == '__main__':
    app.run_server(debug=True, port=8051)

FBruzzesi FBruzzesi · Accepted Answer · 2020-01-14T19:29:26

I am not sure of what your final goal is, but you can initialize an empty and hidden html.Div(...), and later use it to store the input from the callback. After that you will be able to access to it from any other callback.

How to save plotly dash Input as global variable

1 Answers