Dash callback stops working when interacting with sqlite

@simonkragh wrote:

Hi,
I have a relatively simple app as follows:

import dash
import dash_core_components as dcc
import dash_html_components as html
import dash_bootstrap_components as dbc
from dash.dependencies import Input, Output
from layout_constructor import create_header
import dao
import sqlite3
from sqlalchemy import create_engine
import pandas as pd 

conn = create_engine('sqlite:///G:/pyplicate/attunity.db')


def query(q):
    df = pd.read_sql_query(sql=q, con=conn)
    return df 

def get_summary_server_details():
    server_details_query = f'''SELECT cdc_inserts_count, cdc_update_count, cdc_delete_count, cdc_ddl_count 
        FROM taskDetails ORDER BY status_timestamp DESC LIMIT 1'''

    return query(server_details_query)

external_stylesheets = [
    'https://codepen.io/chriddyp/pen/bWLwgP.css', dbc.themes.SUPERHERO]

app = dash.Dash(__name__, external_stylesheets=external_stylesheets)

app.layout = html.Div([
    create_header(),
    html.Div(
        [
            dcc.Interval(
                id='interval-component',
                interval=1*1000,
                n_intervals=0
            )
        ]
    )
])


@app.callback(
    Output(component_id='agg-running-task', component_property='children'),
    [Input(component_id='interval-component', component_property='n_intervals')]
)
def update_output_div(n):
    #sql_result = pd.read_sql_query('SELECT cdc_inserts_count, cdc_update_count, cdc_delete_count, cdc_ddl_count FROM taskDetails ORDER BY status_timestamp DESC LIMIT 1', con=conn)

    return 'Ok!'
    # return 'You\'ve entered "{}"'.format(input_value)


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

For now the callback returns ‘Ok’. The moment i uncomment the “sql_result” line i cant get the callback to return anything. Not even “Ok”. Does anyone have a clue why uncommenting this one line breaks the whole app?

Any help is highly appreciated.

Best Regards,
Simon

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Participants: 2

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