Jinja2 template in Python 3 renders bytes with "b" prefix and quotes

Question

I'm upgrading a Flask app from python2 to python3,

Jinja2 now renders bytes with trailing b and single quotes, e.g. b'a123' while I need them rendered as a123.

This happens with all urlsafe strings which came as string [not unicode] in python2 and were rendered as needed. Now they are bytes

I would like to avoid checking type every time and adding .decode('utf-8')

Answer 1

I encounter the same problem. Maybe it has been solved for you since the quetion has been past so long time.

In my problem, I open the file with 'rb' mode, and read() method for file handler will return <type 'bytes'>, so jinja2 Template.render() will also return a string wrapper of string. (Just something you call it bytes with prefix 'b' and quotes)

with open("file.txt", "rb") as f:
    text = f.read()
    # type(text) -> <class 'bytes'>
    template = Template(f.read())
    template.render(kwargs)

After I modify the open mode with 'r', this time everything works as expected.

with open("file.txt", "r") as f:
    text = f.read()
    # type(text) -> <class 'str'>
    template = Template(text)
    template.render(kwargs)

So the problem is the type of real parameter in Template constructor function.