With a recent project I wanted to offer a download of a bunch of files as a ZIP download to make redistribution. I started by thinking that this would involve creating a zip file on disk and then serving it to the client.
It doesn’t.
This method creates an in-memory zip image of a temporary directory in which the required file are created. The directory is deleted before the zip file is returned to the client. Note the use of send_file to return the content and how it allows us to specify the name of the downloaded file.
If running the app under uwsgi there are some precautions to take:
- import the send_file module from flask (the default wsgi version is broken)
- Include ‘wsgi-disable-file-wrapper’ in the uwsgi settings
import os
import io
import tempfile
import zipfile
from peewee import *
# A simple function to write a file in a given directory
def makeFile(dir, filename, data):
fname = str(dir) + '/' + str(filename)
fh = open(fname, "w")
fh.write(data)
fh.close()
return True
"""
Function to create a zip file containing the application configuration files
To create the zip file, we need to create a memory file (BytesIO))
Params:
row: Database row object containing columns for filename and
content to be written in the form
{ {"file1": "Content for file 1}, {"file2": "Different content for file"} }
Returns:
data: BytesIO object containing the zipped files
"""
def mkZipFile(row):
zipdir = tempfile.mkdtemp(prefix='/tmp/')
oldpath = os.getcwd()
os.chdir(zipdir)
jdata = json.loads(row)
for conf in jdata:
for f in conf:
makeFile(zipdir, f, conf[f])
# Create the in-memory zip image
data = io.BytesIO()
with zipfile.ZipFile(data, mode='w') as z:
for fname in os.listdir("."):
z.write(fname)
os.unlink(fname)
data.seek(0)
os.chdir(oldpath)
os.rmdir(zipdir)
return data
The route takes the form
"""
Route to create a zip file containing all the required data files
Params:
id: the numeric id of the record in the database
Returns:
ZIP: file in ZIP format containing the download files
"""
@app.route('/download/<int:id>.zip', methods=['GET'])
def showZip(id):
rs = db_table.select(db_table.data_column).where(db_table.id == id).get()
zfile = mkZipFile(rs)
if not zfile:
return Response(response="Invalid zip file", status="400")
return send_file(
zfile,
mimetype='application/zip',
as_attachment=True,
attachment_filename='file_bundle.zip')
References
