Agfdhyk

I am working with a SQL Server database table similar to this

USER_ID varchar(50), FILE_NAME ntext, FILE_CONTENT ntext

sample data:

USER_ID:      1

FILE_NAME:    (AttachedFiles:1)=file1.pdf

FILE_CONTENT: (AttachedFiles:1)=H4sIAAAAAAAAAOy8VXQcy7Ku….

Means regular expressions I have successfully isolated the "content" of the FILE_CONTENT field by removing the "(AttachedFiles:1)=" part resulting with a string similar to this:

content_str = "H4sIAAAAAAAAAOy8VXQcy7Ku22JmZmZmspiZGS2WLGa0xc…"

My plan was to reconstruct the file using this string to download it from the database. During my investigation process, I found this post and proceeded to replicate the code like this:

content_str = 'H4sIAAAAAAAAAO19B0AUR/v33...'

with open(os.path.expanduser('test.pdf'), 'wb') as f:

    f.write(base64.decodestring(content_str))

...getting a TypeError: expected bytes-like object, not str

Investigating further, I found this other post and proceeded like this:

content_str = 'H4sIAAAAAAAAAO19B0AUR/v33...'

encoded = content_str.encode('ascii')

with open(os.path.expanduser('test.pdf'), 'wb') as f:

    f.write(base64.decodestring(encoded))

...resulting as a successful creation of a PDF. However, when trying to open it, I get an error saying that the file is corrupt.

I kindly ask you for any suggestions on how to proceed. I am even open to rethink the process I've came up with if necessary. Many thanks in advance!

The value of the FILE_CONTENT is base64-encoded. This means it's a string consisting of 64 possible characters which represent raw bytes. All you need to do is base64-decode the string and write the resulting bytes directly to a file.

import base64



content_str = "H4sIAAAAAAAAAOy8VXQcy7Ku22JmZmZmspiZGS2WLGa0xc=="



with open(os.path.expanduser('test.pdf'), 'wb') as fp:

    fp.write(base64.b64decode(content_str))

The base64 sequence "H4sI" at the start of your content string translates to the bytes 0x1f, 0x8b, 0x08. These bytes are not normally at the start of a PDF file, but indicate a gzip-compressed data stream. It's possible that a PDF reader won't understand this.

I don't know for certain if gzip compression is a valid part of the PDF file format, but it's a valid part of web communication, so maybe the file stream was compressed for transfer/download and has not been decompressed before writing it to the database.

If your PDF reader does not accept the data as is, decompress it before saving it to file:

import gzip



# ...



with open(os.path.expanduser('test.pdf'), 'wb') as fp:

    fp.write(gzip.decompress(base64.b64decode(content_str)))