Dash Download In-memory Generated File On Button Click: How To Give Filename?

I generate an in-memory Excel file via pd.ExcelWriter and BytesIO for a click event in my Python3.8 dash app. Everything works as it should be. When I download my file I get this

Solution 1:

You could use the Download component from the dash-extensions package,

pip install dash-extensions == 0.0.18

The syntax is simpler, and it has a filename argument. Here is a small example,

import dash
import dash_html_components as html
import numpy as np
import pandas as pd

from dash.dependencies import Output, Input
from dash_extensions import Download
from dash_extensions.snippets import send_bytes

# Generate some example data.
data = np.column_stack((np.arange(10), np.arange(10) * 2))
df = pd.DataFrame(columns=["a column", "another column"], data=data)
# Create app.
app = dash.Dash(prevent_initial_callbacks=True)
app.layout = html.Div([html.Button("Download xlsx", id="btn"), Download(id="download")])


@app.callback(Output("download", "data"), [Input("btn", "n_clicks")])defgenerate_xlsx(n_nlicks):

    defto_xlsx(bytes_io):
        xslx_writer = pd.ExcelWriter(bytes_io, engine="xlsxwriter")
        df.to_excel(xslx_writer, index=False, sheet_name="sheet1")
        xslx_writer.save()

    return send_bytes(to_xlsx, "some_name.xlsx")


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

Disclaimer: I am the author of the dash-extensions package.