TypeError: Can't use a string pattern on a bytes-like object

When I try to export a file with the flags --gfm --export, I get the following error:

grip --gfm --export Kalender.md
Exporting to Kalender.html
Traceback (most recent call last):
  File "/usr/local/bin/grip", line 9, in <module>
    load_entry_point('grip==3.2.0', 'console_scripts', 'grip')()
  File "/usr/local/lib/python3.4/dist-packages/grip/command.py", line 78, in main
    True, args['<address>'])
  File "/usr/local/lib/python3.4/dist-packages/grip/exporter.py", line 36, in export
    render_offline, render_wide, render_inline)
  File "/usr/local/lib/python3.4/dist-packages/grip/exporter.py", line 18, in render_page
    return render_app(app)
  File "/usr/local/lib/python3.4/dist-packages/grip/renderer.py", line 8, in render_app
    response = c.get('/')
  File "/usr/local/lib/python3.4/dist-packages/werkzeug/test.py", line 774, in get
    return self.open(*args, **kw)
  File "/usr/local/lib/python3.4/dist-packages/flask/testing.py", line 108, in open
    follow_redirects=follow_redirects)
  File "/usr/local/lib/python3.4/dist-packages/werkzeug/test.py", line 742, in open
    response = self.run_wsgi_app(environ, buffered=buffered)
  File "/usr/local/lib/python3.4/dist-packages/werkzeug/test.py", line 659, in run_wsgi_app
    rv = run_wsgi_app(self.application, environ, buffered=buffered)
  File "/usr/local/lib/python3.4/dist-packages/werkzeug/test.py", line 867, in run_wsgi_app
    app_iter = app(environ, start_response)
  File "/usr/local/lib/python3.4/dist-packages/flask/app.py", line 1836, in __call__
    return self.wsgi_app(environ, start_response)
  File "/usr/local/lib/python3.4/dist-packages/flask/app.py", line 1820, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/usr/local/lib/python3.4/dist-packages/flask/app.py", line 1403, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python3.4/dist-packages/flask/_compat.py", line 33, in reraise
    raise value
  File "/usr/local/lib/python3.4/dist-packages/flask/app.py", line 1817, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/local/lib/python3.4/dist-packages/flask/app.py", line 1470, in full_dispatch_request
    self.try_trigger_before_first_request_functions()
  File "/usr/local/lib/python3.4/dist-packages/flask/app.py", line 1497, in try_trigger_before_first_request_functions
    func()
  File "/usr/local/lib/python3.4/dist-packages/grip/server.py", line 111, in retrieve_styles
    app.config['STYLE_ASSET_URLS_INLINE']))
  File "/usr/local/lib/python3.4/dist-packages/grip/server.py", line 304, in _get_styles
    content = re.sub(asset_pattern, match_asset, _download(app, style_url))
  File "/usr/lib/python3.4/re.py", line 175, in sub
    return _compile(pattern, flags).sub(repl, string, count)
TypeError: can't use a string pattern on a bytes-like object

[ssokolow]

I ran into that error while working to get one of my scripts working on Python 3.x. Thankfully, I was working on a unit test suite because, given the kind of code it was, it needed to accept varied input and that was a pain to get the semantics correct for.

Judging by that backtrace, asset_pattern is str() while _download(app, style_url) is returning bytes().

In Python 2.x, str = bytes and it’ll automatically coerce str to unicode as necessary (causing a UnicodeDecodeError if the string contains characters outside the 7-bit ASCII range… which isn’t a problem with hard-coded regex patterns).

In Python 3.x, str = unicode and it treats str<->bytes conversion as strictly as it treats str<->int conversion.

The solution is to either make _download return a decoded Unicode string or make the regex pattern a bytes. (I prefer doing the former by using the Requests library’s Response.text property to retrieve the content.)

[joeyespo]

Addressed this in b995503fc8e73000ca8fc541fa325f3999154c9b and 92d2f2c85f9768f129e03dc86c60a33f5cebea22. I tested it with Python 3.4.2. Try installing from master and seeing if it works for you too. Feel free to re-open if it’s still broken.

Thanks!