I have several csv-files, some of which are compressed but others are not, all in a 7z archive. I want to read the csv files and save the content in a database. However, whenever py7zlib attemts to read the data from a csv file that is actually not compressed, I get the error data error during decompression.
import os
import py7zlib
scr = r'Y:\PathtoArchive'
z7file = 'ArchiveName.7z'
with open(os.path.join(scr,z7file),'rb') as f:
archive = py7zlib.Archive7z(f)
names = archive.filenames
for mem in names:
obj = archive.getmember(mem)
print obj.compressed # prints None for uncompressed data
try:
data = obj.read()
except Exception as er:
print er # prints data error during decompression
# whenever obj.compressed is None
The error happens in
File "C:\Anaconda\lib\site-packages\py7zlib.py", line 608, in read
data = getattr(self, decoder)(coder, data, level)
File "C:\Anaconda\lib\site-packages\py7zlib.py", line 671, in _read_lzma
return self._read_from_decompressor(coder, dec, input, level, checkremaining=True, with_cache=True)
File "C:\Anaconda\lib\site-packages\py7zlib.py", line 646, in _read_from_decompressor
tmp = decompressor.decompress(data)
ValueError: data error during decompression
So, how can I extract uncompressed data from a 7z-Archive?
Though I couldn't really figure out what the problem seemed to be, I found a workaround that solved the ultimate goal to obtain the data from csv-files from a 7z-archive. 7-zip comes with a command line tool. Communicating with that tool via the subprocess module, I could automatically extract the files that I wihsed to extract without any problems
import subprocess
import py7zlib
archiveman = r'c:\Program Files\7-zip\7z' # 7z.exe comes with 7-zip
archivepath = r'C:\Path\to\archive.7z'
with open(archivepath,'rb') as f:
archive = py7zlib.Archive7z(f)
names = archive.filenames
for name in names:
_ = subprocess.check_output([archiveman, 'e', archivepath, '-o{}'.format(r'C:\Destination\of\copy'), name])
The different commands that can be used with 7z can be found here.