Python – Pandas XLSXWriter – returns instead of writing

I want to return an Excel file from my Flask (Python) server. This code:

writer = pd. ExcelWriter('filename.xlsx')
dataframe.to_excel(writer, index=False)
writer.save()

Write the Excel file to the file system. How do I return a file instead of writing to it?

You can use StringIO or BytesIO objects to write excel data to memory.

This code was copied from the pandas documentation here :

# Safe import for either Python 2.x or 3.x
try:
    from io import BytesIO
except ImportError:
    from cStringIO import StringIO as BytesIO

bio = BytesIO()

# By setting the 'engine' in the ExcelWriter constructor.
writer = ExcelWriter(bio, engine='xlsxwriter')
df.to_excel(writer, sheet_name='Sheet1')

# Save the workbook
writer.save()

# Seek to the beginning and read to copy the workbook to a variable in memory
bio.seek(0)
workbook = bio.read()