How to create a a pop-up, modal, or confirm dialog when the file user upload is not a CSV file

Dash Python
3

Hi, @flyingcujo, my parse_content def is not assoc with a callback, so I don’t know how to call the bootstrap Modal I created.

Below is the code I write for the upload component that creates a data table.

import base64
import datetime
import io

import dash
from dash.dependencies import Input, Output, State
import dash_core_components as dcc
import dash_html_components as html
import dash_table

import pandas as pd


external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']

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

app.layout = html.Div([
    dcc.Upload(
        id='datatable-upload',
        children=html.Div([
            'Drag and Drop or ',
            html.A('Select Files')
        ]),
        style={
            'width': '100%',
            'height': '60px',
            'lineHeight': '60px',
            'borderWidth': '1px',
            'borderStyle': 'dashed',
            'borderRadius': '5px',
            'textAlign': 'center',
            'margin': '10px'
        },
        # Allow multiple files to be uploaded

    ),
    html.Div(id='output-data-upload'),
])


def parse_contents(contents, filename):
    content_type, content_string = contents.split(',')
    decoded = base64.b64decode(content_string)
    if 'csv' in filename:
        # Assume that the user uploaded a CSV file
        return pd.read_csv(
            io.StringIO(decoded.decode('utf-8')))
    elif 'xls' in filename:
        #Assume that the user uploaded an excel file
        return pd.read_excel(io.BytesIO(decoded))

@app.callback(Output('output-data-upload', 'children'),
               [Input('datatable-upload', 'contents')],
               [State('datatable-upload', 'filename')])
def update_output(contents, filename):
    if contents is None:
        return []
    df = parse_contents(contents, filename)
    return html.Div([
        dash_table.DataTable(
            id='table',
            style_data={
                'whiteSpace': 'normal',
                'height': 'auto'
            },
            style_table={'overflowX': 'scroll',
                         'maxHeight': '300',
                         'overflowY': 'scroll',
                         'maxWidth': '300'},
            style_cell={
                'minWidth': '150px', 'maxWidth': '180px',
                'whiteSpace': 'normal',
                'textAlign': 'left'
            },
            style_header={
                'fontWeight': 'bold',
            },
            fixed_rows={'headers': True, 'data': 0},
            columns=[{"name": i, "id": i, 'deletable': True, 'renamable': True} for i in df.columns],
            data=df.to_dict("records"),
            
        )
    ])



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