How to serve users a dynamically generated ZIP archive in Django?
I'm making a site, where users can choose any combination of available books and download them as ZIP archive. I'm worried that generating such archives for each request would slow my server down to a crawl. I have also heard that Django doesn't currently have a good solution for serving dynamically generated files.
The solution is as follows.
Use Python module zipfile to create zip archive, but as the file specify StringIO object (ZipFile constructor requires file-like object). Add files you want to compress. Then in your Django application return the content of StringIO object in HttpResponse with mimetype set to application/x-zip-compressed (or at least application/octet-stream). If you want, you can set content-disposition header, but this should not be really required.
But beware, creating zip archives on each request is bad idea and this may kill your server (not counting timeouts if the archives are large). Performance-wise approach is to cache generated output somewhere in filesystem and regenerate it only if source files have changed. Even better idea is to prepare archives in advance (eg. by cron job) and have your web server serving them as usual statics.
Here's a Django view to do this:
import os
import zipfile
import StringIO
from django.http import HttpResponse
def getfiles(request):
# Files (local path) to put in the .zip
# FIXME: Change this (get paths from DB etc)
filenames = ["/tmp/file1.txt", "/tmp/file2.txt"]
# Folder name in ZIP archive which contains the above files
# E.g [thearchive.zip]/somefiles/file2.txt
# FIXME: Set this to something better
zip_subdir = "somefiles"
zip_filename = "%s.zip" % zip_subdir
# Open StringIO to grab in-memory ZIP contents
s = StringIO.StringIO()
# The zip compressor
zf = zipfile.ZipFile(s, "w")
for fpath in filenames:
# Calculate path for file in zip
fdir, fname = os.path.split(fpath)
zip_path = os.path.join(zip_subdir, fname)
# Add file, at correct path
zf.write(fpath, zip_path)
# Must close zip for all contents to be written
zf.close()
# Grab ZIP file from in-memory, make response with correct MIME-type
resp = HttpResponse(s.getvalue(), mimetype = "application/x-zip-compressed")
# ..and correct content-disposition
resp['Content-Disposition'] = 'attachment; filename=%s' % zip_filename
return resp
Many answers here suggest to use a StringIO or BytesIO buffer. However this is not needed as HttpResponse is already a file-like object:
response = HttpResponse(content_type='application/zip')
zip_file = zipfile.ZipFile(response, 'w')
for filename in filenames:
zip_file.write(filename)
response['Content-Disposition'] = 'attachment; filename={}'.format(zipfile_name)
return response
Note that you should not call zip_file.close() as the open "file" is response and we definitely don't want to close it.
I used Django 2.0 and Python 3.6.
import zipfile
import os
from io import BytesIO
def download_zip_file(request):
filelist = ["path/to/file-11.txt", "path/to/file-22.txt"]
byte_data = BytesIO()
zip_file = zipfile.ZipFile(byte_data, "w")
for file in filelist:
filename = os.path.basename(os.path.normpath(file))
zip_file.write(file, filename)
zip_file.close()
response = HttpResponse(byte_data.getvalue(), content_type='application/zip')
response['Content-Disposition'] = 'attachment; filename=files.zip'
# Print list files in zip_file
zip_file.printdir()
return response
For python3 i use the io.ByteIO since StringIO is deprecated to achieve this. Hope it helps.
import io
def my_downloadable_zip(request):
zip_io = io.BytesIO()
with zipfile.ZipFile(zip_io, mode='w', compression=zipfile.ZIP_DEFLATED) as backup_zip:
backup_zip.write('file_name_loc_to_zip') # u can also make use of list of filename location
# and do some iteration over it
response = HttpResponse(zip_io.getvalue(), content_type='application/x-zip-compressed')
response['Content-Disposition'] = 'attachment; filename=%s' % 'your_zipfilename' + ".zip"
response['Content-Length'] = zip_io.tell()
return response
Django doesn't directly handle the generation of dynamic content (specifically Zip files). That work would be done by Python's standard library. You can take a look at how to dynamically create a Zip file in Python here.
If you're worried about it slowing down your server you can cache the requests if you expect to have many of the same requests. You can use Django's cache framework to help you with that.
Overall, zipping files can be CPU intensive but Django shouldn't be any slower than another Python web framework.
Shameless plug: you can use django-zipview for the same purpose.
After a pip install django-zipview:
from zipview.views import BaseZipView
from reviews import Review
class CommentsArchiveView(BaseZipView):
"""Download at once all comments for a review."""
def get_files(self):
document_key = self.kwargs.get('document_key')
reviews = Review.objects \
.filter(document__document_key=document_key) \
.exclude(comments__isnull=True)
return [review.comments.file for review in reviews if review.comments.name]
I suggest to use separate model for storing those temp zip files. You can create zip on-fly, save to model with filefield and finally send url to user.
Advantages:
Serving static zip files with django media mechanism (like usual uploads).
Ability to cleanup stale zip files by regular cron script execution (which can use date field from zip file model).
A lot of contributions were made to the topic already, but since I came across this thread when I first researched this problem, I thought I'd add my own two cents.
Integrating your own zip creation is probably not as robust and optimized as web-server-level solutions. At the same time, we're using Nginx and it doesn't come with a module out of the box.
You can, however, compile Nginx with the mod_zip module (see here for a docker image with the latest stable Nginx version, and an alpine base making it smaller than the default Nginx image). This adds the zip stream capabilities.
Then Django just needs to serve a list of files to zip, all done!
It is a little more reusable to use a library for this file list response, and django-zip-stream offers just that.
Sadly it never really worked for me, so I started a fork with fixes and improvements.
You can use it in a few lines:
def download_view(request, name=""):
from django_zip_stream.responses import FolderZipResponse
path = settings.STATIC_ROOT
path = os.path.join(path, name)
return FolderZipResponse(path)
You need a way to have Nginx serve all files that you want to archive, but that's it.
Can't you just write a link to a "zip server" or whatnot? Why does the zip archive itself need to be served from Django? A 90's era CGI script to generate a zip and spit it to stdout is really all that's required here, at least as far as I can see.
Related
I'm quite new on Django and i'm looking for a way to dwonload a zip file from my django site but i have some issue when i'm running this piece of code:
def download(self):
dirName = settings.DEBUG_FOLDER
name = 'test.zip'
with ZipFile(name, 'w') as zipObj:
# Iterate over all the files in directory
for folderName, subfolders, filenames in os.walk(dirName):
for filename in filenames:
# create complete filepath of file in directory
filePath = os.path.join(folderName, filename)
# Add file to zip
zipObj.write(filePath, basename(filePath))
path_to_file = 'http://' + sys.argv[-1] + '/' + name
resp= {}
# Grab ZIP file from in-memory, make response with correct MIME-type
resp = HttpResponse(content_type='application/zip')
# ..and correct content-disposition
resp['Content-Disposition'] = 'attachment; filename=%s' % smart_str(name)
resp['X-Sendfile'] = smart_str(path_to_file)
return resp
I get:
Exception Value:
<HttpResponse status_code=200, "application/zip"> is not JSON serializable
I tried to change the content_type to octet-stream but it doesn't work
And to use a wrapper as followw:
wrapper = FileWrapper(open('test.zip', 'rb'))
content_type = 'application/zip'
content_disposition = 'attachment; filename=name'
# Grab ZIP file from in-memory, make response with correct MIME-type
resp = HttpResponse(wrapper, content_type=content_type)
# ..and correct content-disposition
resp['Content-Disposition'] = content_disposition
I didn't find useful answer so far but maybe I didn't search well, so if it seems my problem had been already traited, feel free to notify me
Thank you very much for any help
You have to send the zip file as byte
response = HttpResponse(zipObj.read(), content_type="application/zip")
response['Content-Disposition'] = 'attachment; filename=%s' % smart_str(name)
return response
I would do like this:
(Caveat I use wsl so the python function will make use of cmd lines)
In view:
import os
def zipdownfun(request):
""" Please establish in settings.py where media file should be downloaded from.
In my case is media with a series of other folders inside. Media folder is at the same level of project root folder, where settings.py is"""
file_name = os.path.join(MEDIA_URL,'folder_where_your_file_is','file_name.zip')
"""let us put the case that you have zip folder in media folder"""
file_folder_path = os.path.join(MEDIA_URL,'saving_folder')
"""The command line takes as first variable the name of the
future zip file and as second variable the destination folder"""
cmd = f'zip {file_name} {file_folder_path}'
"""With os I open a process in the background so that some magic
happens"""
os.system(cmd)
"""I don't know what you want to do with this, but I placed the
URL of the file in a button for the download, so you will need
the string of the URL to place in href of an <a> element"""
return render(request,'your_html_file.html', {'url':file_name})
The db I have created, will be updated very often. I used a slightly different version of this function with -r clause since I had to zip, each time, a folder. Why I did this? The database I have created has to allow the download of this zipped folder. This folder will be updated daily. So this function basically overwrites the file each time that is downloaded. It will be so fresh of new data each time.
Please refer to this page to understand how to create a button for the download of the generated file.
Take as reference approach 2. The URL variable that you are passing to the Django template should be used at the place of the file (screenshot attached)
I hope it can help!
I am currently working on a small web interface which allows different users to upload files, convert the files they have uploaded, and download the converted files. The details of the conversion are not important for my question.
I am currently using flask-uploads to manage the uploaded files, and I am storing them in the file system. Once a user uploads and converts a file, there are all sorts of pretty buttons to delete the file, so that the uploads folder doesn't fill up.
I don't think this is ideal. What I really want is for the files to be deleted right after they are downloaded. I would settle for the files being deleted when the session ends.
I've spent some time trying to figure out how to do this, but I have yet to succeed. It doesn't seem like an uncommon problem, so I figure there must be some solution out there that I am missing. Does anyone have a solution?
There are several ways to do this.
send_file and then immediately delete (Linux only)
Flask has an after_this_request decorator which could work for this use case:
#app.route('/files/<filename>/download')
def download_file(filename):
file_path = derive_filepath_from_filename(filename)
file_handle = open(file_path, 'r')
#after_this_request
def remove_file(response):
try:
os.remove(file_path)
file_handle.close()
except Exception as error:
app.logger.error("Error removing or closing downloaded file handle", error)
return response
return send_file(file_handle)
The issue is that this will only work on Linux (which lets the file be read even after deletion if there is still an open file pointer to it). It also won't always work (I've heard reports that sometimes send_file won't wind up making the kernel call before the file is already unlinked by Flask). It doesn't tie up the Python process to send the file though.
Stream file, then delete
Ideally though you'd have the file cleaned up after you know the OS has streamed it to the client. You can do this by streaming the file back through Python by creating a generator that streams the file and then closes it, like is suggested in this answer:
def download_file(filename):
file_path = derive_filepath_from_filename(filename)
file_handle = open(file_path, 'r')
# This *replaces* the `remove_file` + #after_this_request code above
def stream_and_remove_file():
yield from file_handle
file_handle.close()
os.remove(file_path)
return current_app.response_class(
stream_and_remove_file(),
headers={'Content-Disposition': 'attachment', 'filename': filename}
)
This approach is nice because it is cross-platform. It isn't a silver bullet however, because it ties up the Python web process until the entire file has been streamed to the client.
Clean up on a timer
Run another process on a timer (using cron, perhaps) or use an in-process scheduler like APScheduler and clean up files that have been on-disk in the temporary location beyond your timeout (e. g. half an hour, one week, thirty days, after they've been marked "downloaded" in RDMBS)
This is the most robust way, but requires additional complexity (cron, in-process scheduler, work queue, etc.)
You can also store the file's data in memory, delete it, then serve what you have in memory.
For example, if you were serving a PDF:
import io
import os
#app.route('/download')
def download_file():
file_path = get_path_to_your_file()
return_data = io.BytesIO()
with open(file_path, 'rb') as fo:
return_data.write(fo.read())
# (after writing, cursor will be at last byte, so move it to start)
return_data.seek(0)
os.remove(file_path)
return send_file(return_data, mimetype='application/pdf',
attachment_filename='download_filename.pdf')
(above I'm just assuming it's PDF, but you can get the mimetype programmatically if you need)
Flask has an after_request decorator which could work in this case:
#app.route('/', methods=['POST'])
def upload_file():
uploaded_file = request.files['file']
file = secure_filename(uploaded_file.filename)
#app.after_request
def delete(response):
os.remove(file_path)
return response
return send_file(file_path, as_attachment=True, environ=request.environ)
Based on #Garrett comment, the better approach is to not blocking the send_file while removing the file. IMHO, the better approach is to remove it in the background, something like the following is better:
import io
import os
from flask import send_file
from multiprocessing import Process
#app.route('/download')
def download_file():
file_path = get_path_to_your_file()
return_data = io.BytesIO()
with open(file_path, 'rb') as fo:
return_data.write(fo.read())
return_data.seek(0)
background_remove(file_path)
return send_file(return_data, mimetype='application/pdf',
attachment_filename='download_filename.pdf')
def background_remove(path):
task = Process(target=rm(path))
task.start()
def rm(path):
os.remove(path)
I am avoiding the creation of files on disk, this is what I have got so far:
def get_zip(request):
import zipfile, StringIO
i = open('picture.jpg', 'rb').read()
o = StringIO.StringIO()
zf = zipfile.ZipFile(o, mode='w')
zf.writestr('picture.jpg', i)
zf.close()
o.seek(0)
response = HttpResponse(o.read())
o.close()
response['Content-Type'] = 'application/octet-stream'
response['Content-Disposition'] = "attachment; filename=\"picture.zip\""
return response
Do you think is correct-elegant-pythonic enough? Any better way to do it?
Thanks!
For StringIO you should generally use o.getvalue() to get the result. Also, if you want to add a normal file to the zip file, you can use zf.write('picture.jpg'). You don't need to manually read it.
Avoiding disk files can slow your server to a crawl, but it will certainly work.
You'll exhaust memory if you serve too many of these requests concurrently.
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Serving dynamically generated ZIP archives in Django
(Feel free to point me to any potential duplicates if I have missed them)
I have looked at this snippet:
http://djangosnippets.org/snippets/365/
and this answer:
but I wonder how I can tweak them to suit my need: I want multiple files to be zipped and the archive available as a download via a link (or dynamically generated via a view). I am new to Python and Django so I don't know how to go about it.
Thank in advance!
I've posted this on the duplicate question which Willy linked to, but since questions with a bounty cannot be closed as a duplicate, might as well copy it here too:
import os
import zipfile
import StringIO
from django.http import HttpResponse
def getfiles(request):
# Files (local path) to put in the .zip
# FIXME: Change this (get paths from DB etc)
filenames = ["/tmp/file1.txt", "/tmp/file2.txt"]
# Folder name in ZIP archive which contains the above files
# E.g [thearchive.zip]/somefiles/file2.txt
# FIXME: Set this to something better
zip_subdir = "somefiles"
zip_filename = "%s.zip" % zip_subdir
# Open StringIO to grab in-memory ZIP contents
s = StringIO.StringIO()
# The zip compressor
zf = zipfile.ZipFile(s, "w")
for fpath in filenames:
# Calculate path for file in zip
fdir, fname = os.path.split(fpath)
zip_path = os.path.join(zip_subdir, fname)
# Add file, at correct path
zf.write(fpath, zip_path)
# Must close zip for all contents to be written
zf.close()
# Grab ZIP file from in-memory, make response with correct MIME-type
resp = HttpResponse(s.getvalue(), mimetype = "application/x-zip-compressed")
# ..and correct content-disposition
resp['Content-Disposition'] = 'attachment; filename=%s' % zip_filename
return resp
So as I understand your problem is not how to generate dynamically this file, but creating a link for people to download it...
What I suggest is the following:
0) Create a model for your file, if you want to generate it dynamically don't use the FileField, but just the info you need for generating this file:
class ZipStored(models.Model):
zip = FileField(upload_to="/choose/a/path/")
1) Create and store your Zip. This step is important, you create your zip in memory, and then cast it to assign it to the FileField:
function create_my_zip(request, [...]):
[...]
# This is a in-memory file
file_like = StringIO.StringIO()
# Create your zip, do all your stuff
zf = zipfile.ZipFile(file_like, mode='w')
[...]
# Your zip is saved in this "file"
zf.close()
file_like.seek(0)
# To store it we can use a InMemoryUploadedFile
inMemory = InMemoryUploadedFile(file_like, None, "my_zip_%s" % filename, 'application/zip', file_like.len, None)
zip = ZipStored(zip=inMemory)
# Your zip will be stored!
zip.save()
# Notify the user the zip was created or whatever
[...]
2) Create a url, for example get a number matching the id, you can also use a slugfield (this)
url(r'^get_my_zip/(\d+)$', "zippyApp.views.get_zip")
3) Now the view, this view will return the file matching the id passed in the url, you can also use a slug sending the text instead of the id, and make the get filtering by your slugfield.
function get_zip(request, id):
myzip = ZipStored.object.get(pk = id)
filename = myzip.zip.name.split('/')[-1]
# You got the zip! Now, return it!
response = HttpResponse(myzip.file, content_type='application/zip')
response['Content-Disposition'] = 'attachment; filename=%s' % filename
I have a small project that would be perfect for Google App Engine. Implementing it hinges on the ability to generate a ZIP file and return it.
Due to the distributed nature of App Engine, from what I can tell, the ZIP file couldn't be created "in-memory" in the traditional sense. It would basically have to be generated and and sent in a single request/response cycle.
Does the Python zip module even exist in the App Engine environment?
zipfile is available at appengine and reworked example follows:
from contextlib import closing
from zipfile import ZipFile, ZIP_DEFLATED
from google.appengine.ext import webapp
from google.appengine.api import urlfetch
def addResource(zfile, url, fname):
# get the contents
contents = urlfetch.fetch(url).content
# write the contents to the zip file
zfile.writestr(fname, contents)
class OutZipfile(webapp.RequestHandler):
def get(self):
# Set up headers for browser to correctly recognize ZIP file
self.response.headers['Content-Type'] ='application/zip'
self.response.headers['Content-Disposition'] = \
'attachment; filename="outfile.zip"'
# compress files and emit them directly to HTTP response stream
with closing(ZipFile(self.response.out, "w", ZIP_DEFLATED)) as outfile:
# repeat this for every URL that should be added to the zipfile
addResource(outfile,
'https://www.google.com/intl/en/policies/privacy/',
'privacy.html')
addResource(outfile,
'https://www.google.com/intl/en/policies/terms/',
'terms.html')
import zipfile
import StringIO
text = u"ABCDEFGHIJKLMNOPQRSTUVWXYVabcdefghijklmnopqqstuvweyxáéöüï东 廣 広 广 國 国 国 界"
zipstream=StringIO.StringIO()
file = zipfile.ZipFile(file=zipstream,compression=zipfile.ZIP_DEFLATED,mode="w")
file.writestr("data.txt.zip",text.encode("utf-8"))
file.close()
zipstream.seek(0)
self.response.headers['Content-Type'] ='application/zip'
self.response.headers['Content-Disposition'] = 'attachment; filename="data.txt.zip"'
self.response.out.write(zipstream.getvalue())
From What is Google App Engine:
You can upload other third-party
libraries with your application, as
long as they are implemented in pure
Python and do not require any
unsupported standard library modules.
So, even if it doesn't exist by default you can (potentially) include it yourself. (I say potentially because I don't know if the Python zip library requires any "unsupported standard library modules".