Python: Want to write zipfile.ZipFile object to disk as "foo.zip"

It feels like I'm missing something obvious here.

I have a zipfile.ZipFile object, which was created by writing files into it using io.BytesIO() called buffer as follows:

with zipfile.ZipFile(buffer, "a") as zip:
    # write some things into the zip using zip.write()

then I returned zip, so I have a zipfile.ZipFile object.

I want to write this object to disk as a zipped file, and I don't know how.

zip.write('foo.zip')

would write things into the object, and

with open('foo.zip', 'wb') as f:
    f.write(zip)

doesn't work because zip isn't a bytes object.

with open('foo.zip', 'wb') as f:
    f.write(zip.read())

doesn't work because it's expecting a "name", which I presume is the name of one of the files saved within zip. I would have assumed there was just some simple way to do this, e.g. zip.to_zip("foo.zip")?

UPDATE: Because zip was originally written into the buffer, I tried changing zip.filename to "test.zip" which does write the zip to disk. However, the contents of zip aren't there. This could be a different issue, but I'm unsure.

Solution

You need to write contents of buffer, not zip, since everything you write using zip.write(filename) is being put into the buffer, as you passed it as a first argument of zipfile.ZipFile() call.

I would also suggest to avoid using zip as a variable name since it shadows built-in zip(*iterables) function.

Here is an example:

buffer = io.BytesIO()

with zipfile.ZipFile(buffer, "a") as zip_file:
    zip_file.write('data.txt')

with open('foo.zip', 'wb') as f:
    f.write(buffer.getvalue())