base64 encoding of file in Python

Question

I want to use the function base64.encode() to directly encode the contents of a file in Python.

base64.encode(input, output)

Encode the contents of the binary input file and write the resulting base64 encoded data to the output file. input and output must be file objects.

So I do this:

encode(open('existing_file.dat','r'), open('output.dat','w'))

and get the following error:

>>> import base64
>>> base64.encode(open('existing_file.dat','r'), open('output.dat','w'))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.6/base64.py", line 502, in encode
    line = binascii.b2a_base64(s)
TypeError: a bytes-like object is required, not 'str'

To my eye that looks like a bug in /usr/lib/python3.6/base64.py but a big part of me does not want to believe that...

try to open file in byte mode: rb/wb

Azat Ibrakov
– Azat Ibrakov

2017-06-19 11:19:22 +00:00
Commented Jun 19, 2017 at 11:19 — Azat Ibrakov
– Azat Ibrakov, Commented Jun 19, 2017 at 11:19

Azat Ibrakov · Accepted Answer · 2017-06-19 11:22:53Z

8

from docs

when opening a binary file, you should append 'b' to the mode value to open the file in binary mode

so changing

encode(open('existing_file.dat','r'), open('output.dat','w'))

to

encode(open('existing_file.dat','rb'), open('output.dat','wb'))

should work

answered Jun 19, 2017 at 11:22

Azat Ibrakov

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