Is there a way to decode bytes inside a string object in Python? [duplicate]

Question

Let me be more clear.

I'm receiving a string in Python like this:

file = "b'x\\x9c\\xb4'"

The type of file is str. But you can see inside of that string the format of a <class 'bytes'>. It was the result of calling str(file) once file was already encoded. I would like to decode it but i don't know how to decode the bytes inside of a string object.

My question is: is there a way to interpret file as bytes instead of str without having to call something like bytes(file, 'utf-8') or file.encode('utf-8')? The problem with these method is that i would encode the already encoded bytes as i stated before.

Why do i need that?

I'm building an API and i need to send back as a JSON value a significantly big string. Since there was plenty of space for me to compress it, i ended using zlib:

import zlib
file = BIG_STRING
file_compressed = zlib.compress(BIG_STRING.encode(utf-8)) # Since zlib expects a bytes object
send_back({"SOME_BIG_STRING": str(file_compressed)})

I'm sending it back as a string because i can't send it back as a bytes object, it doesn't support that. And if i try to decode it compressed before sending i ended up facing an error:

send_back({"SOME_BIG_STRING": file_compressed.decode('utf-8')})
-> UnicodeDecodeError: utf-8' codec can't decode byte 0x9c in position 1: invalid start byte

And when i receive the same string later in the program, i find myself stuck on the problem described initially.

I'm lacking knowledge right now to be able to do some workaround and couldn't find an answer to this. I'd be extremely grateful if anyone could help me!

what framework do you use to build your API?

dukkee
– dukkee

2021-01-25 20:15:09 +00:00
Commented Jan 25, 2021 at 20:15 — dukkee
– dukkee, Commented Jan 25, 2021 at 20:15

dukkee · Accepted Answer · 2021-01-25 20:13:26Z

0

Anyway, you can call eval("b'x\\x9c\\xb4'") and get your result b'x\x9c\xb4' if you don't find any other solution. But eval usage isn't recommended in the common case and it will be a bad practice.

answered Jan 25, 2021 at 20:13

dukkee

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4 Comments

goalie1998 Over a year ago

```eval`` is a very bad idea for api calls. Not that I have a better one, though.

dukkee Over a year ago

@goalie1998 I know, therefore I wrote about it... Usually frameworks contain compression middleware or package, hope author will write his framework or will find it

Christian França Over a year ago

Thank you! I indeed won't be using eval but your answer showed me a better path to look for a solution. I ended up findind this question wich is pretty much the same as mine and he ended up using ast.literal_eval which only evaluate literals.

dukkee Over a year ago

@ChristianFrança great, thank you for a tip too :)

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