dash_tut_button_callbacks.py

@app.callback(Output('button-query', 'disabled'),
              [Input('my-datatable', 'selected_row_indices')])
def show_hide_query_button(selected_row_indices):
    """ Callback enables/disables the query button depending on the number of rows selected. """
    if len(selected_row_indices) == 1:
        return False
    else:
        return True


@app.callback(Output('textbox-population', 'value'),
              [Input('button-query', 'n_clicks'),
               Input('my-datatable', 'selected_row_indices'),
               Input('my-datatable', 'rows')])
def query_button_clicked(n_clicks, selected_row_indices, rows):
    """ Callback to retrieve the state population and output to the textbox. """
    if n_clicks > 0 and len(selected_row_indices) == 1:
        row_idx = selected_row_indices[0]
        state = rows[row_idx]['state']
        population = df_st.loc[df_st['State'] == state, 'Population'].values
        print(population)
        value = 'Population of ' + state + ' is ' + str(population)
    else:
        n_clicks = 0
        value = 'Select a single row to query in the datatable'
    return value