将文件从ZIP直接提取到另一个ZIP

Question

My goal is to extract certain files from Zip archive and stream them straight to another Zip without having to perform intermediate extraction to the disk.

So far I have:

from zipfile import ZipFile, ZIP_DEFLATED


def stream_conents(src_zip, dst_zip, file_subset_list):
    with ZipFile(src_zip, "r", compression=ZIP_DEFLATED) as src_zip_archive:
        with ZipFile(dst_zip, "w", compression=ZIP_DEFLATED) as dst_zip_archive:
            for zitem in src_zip_archive.namelist():
                if zitem in file_subset_list:
                    zitem_object = src_zip_archive.open(zitem)
                    dst_zip_archive.write(zitem_object, zitem, )

But it just throws TypeError: argument should be string, bytes or integer, not ZipExtFile

Answer 1

You can read the entire file into memory and use writestr to write the archive.

def stream_conents(src_zip, dst_zip, file_subset_list):
    with ZipFile(src_zip, "r", compression=ZIP_DEFLATED) as src_zip_archive:
        with ZipFile(dst_zip, "w", compression=ZIP_DEFLATED) as dst_zip_archive:
            for zitem in src_zip_archive.namelist():
                if zitem in file_subset_list:
                    # warning, may blow up memory
                    dst_zip_archive.writestr(zitem,
                        src_zip_archive.read(zitem))

Starting with python 3.6, ZipFile.open will open archive files in write mode. That lets you write the file in chunks and reduce overall memory usage.

def stream_conents(src_zip, dst_zip, file_subset_list):
    with ZipFile(src_zip, "r", compression=ZIP_DEFLATED) as src_zip_archive:
        with ZipFile(dst_zip, "w", compression=ZIP_DEFLATED) as dst_zip_archive:
            for zitem in src_zip_archive.namelist():
                if zitem in file_subset_list:
                    if sys.version_info >= (3, 6):
                        with src_zip_archive.open(zitem) as from_item:
                            with dst_zip_archive.open(zitem, "w") as to_item:
                                shutil.copyfileobj(from_item, to_item)
                    else:
                        # warning, may blow up memory
                        dst_zip_archive.writestr(zitem, 
                            src_zip_archive.read(zitem))