Live update from dataframe not working

@fabotic wrote:

hello everyone,
i’m trying to make this dashboard update every ten seconds with new data combined with a dropdown menu (which seems to generate an error if i use it), but i’m having some issues on updating it, it looks like the data is not changing after the update, only when i refresh the page.
Here is a reproducible example:

import pandas as pd
import numpy as np
import plotly.express as px
import dash
from datetime import datetime as dt
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output

aa_milne_arr = ['pooh', 'rabbit', 'piglet', 'Christopher']
list_dropdown_report = [{'label':row,'value':row} for row in aa_milne_arr]

def report_json(n):
    np.random.seed(seed=111 * n)
    df = pd.DataFrame(np.random.randint(0,100,size=(1000,10)), columns=list('ABCDEFGHIJ'))
    aa_milne_arr = ['pooh', 'rabbit', 'piglet', 'Christopher']
    df['descricao'] = np.random.choice(aa_milne_arr, 1000, p=[0.5, 0.1, 0.1, 0.3])
    rep = df.to_json()
    return rep

app = dash.Dash(__name__)

app.layout = html.Div([
                html.Div([
                    html.Label('html label'),
                    dcc.Dropdown(
                        id='dropdown',
                        options=list_dropdown_report,
                        multi=True),
                    dcc.Graph(
                        id='report_graph',
                        animate=True,
                        style={'height':'90vh'}
                            )]),
        html.H1('html H1', style={'textAlign':'center','color':'#64C832'}),
        dcc.Interval(
            id='interval-component',
            interval=10*1000,
            n_intervals=0
        ),
        html.Div(id='report_data',style={'display': 'none'})
            ])


@app.callback(
    Output('report_data', 'children'),
    [Input('interval-component','n_intervals')])
def update_output(n):
    return report_json(n)


@app.callback(
    Output('report_graph', 'figure'),
    [Input('report_data','children'),
     Input('dropdown','value')])
def draw_report(data, dropdown_value):
    vars = []
    import_report_data = pd.read_json(data)
    if dropdown_value is not None:
        for var in dropdown_value:
            vars.append(var)
        if vars:
            filtered_report_data = import_report_data[import_report_data['descricao'].isin(vars)]
        else:
            filtered_report_data = import_report_data
    else:
        filtered_report_data = import_report_data
    report_fig = (px.scatter(filtered_report_data,
                                x='A',
                                y='B',
                                color = 'descricao',
                                template='plotly',
                                opacity=0.75,
                                render_mode='webgl'
                                )).update_layout(
                                                showlegend=False)
    return report_fig


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

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