Is it possible to generate and return a ZIP file with App Engine?

Question

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?

Answer 1

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')

Answer 2

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())

Answer 3

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".