Saving zip file in python to disk

Question

I have a bytea object in a database which is a zip file, I can retrieve it and read it as a zip file, but I also want to save it to disk.

I can't work out how to write zf_model to disk. I've also tried zf.write(io.BytesIO(model.model_file)), i.e. not converting to zip first, but that doesn't work either.

This is what I've tried:

from zipfile import ZipFile
from io import BytesIO
        
#Retrieve the zip file from database (zip file is in a field called model_file for object: Model)
model = Model().query.filter_by(param = "test").first()
#convert the retrieved object to a zip file
zf_model = ZipFile(BytesIO(model.model_file), "w")
    
tempfile = "/tmp/test.zip"

with zipfile.ZipFile(tempfile, "w", compression=zipfile.ZIP_DEFLATED) as zf:
    zf.write(zf_model)

Gives error:

TypeError: a bytes-like object is required, not 'ZipFile'

Trying to write the bytea object directly

with open(tempfile, 'w+') as f:
    f.write(model.model_file)      

gives error:

TypeError: write() argument must be str, not bytes

Answer 1

If you retrieve already compressed file from database you may write it to disk without using ZipFile at all.

#Retrieve the zip file from database (zip file is in a field called model_file for object: Model)
model = Model().query.filter_by(param = "test").first()

tempfile = "/tmp/test.zip"

with open(tempfile, 'wb') as f:
    f.write(model.model_file)

Anyway, if your model store plain bytes data (not zipped one), you may do the following

from zipfile import ZipFile

#Retrieve the zip file from database 
model = Model().query.filter_by(param = "test").first()

tempfile = "/tmp/test.zip"

with ZipFile(tempfile, 'w') as f:
    f.writestr('name_of_file_in_zip_archive.txt', model.model_file)