Flask app suddenly stopped working and errors with any passed variable to template : Forums : PythonAnywhere

Flask app suddenly stopped working and errors with any passed variable to template

I have created a small app to test the error is not with my deployment which suddenly stopped working. the result is the same.

2021-06-17 11:55:44,513: Exception on / [GET]
Traceback (most recent call last):
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/flask/app.py", line 2292, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/flask/app.py", line 1815, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/flask/app.py", line 1718, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/flask/_compat.py", line 35, in reraise
    raise value
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/flask/app.py", line 1813, in full_dispatch_request
    rv = self.dispatch_request()
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/flask/app.py", line 1799, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/home/austinsoft/mysite/anglersdb.py", line 7, in homepage
    return render_template("index.html", result={"title": "test0"})
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/flask/templating.py", line 134, in render_template
    return _render(ctx.app.jinja_env.get_or_select_template(template_name_or_list),
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/jinja2/environment.py", line 1068, in get_or_select_template
    return self.get_template(template_name_or_list, parent, globals)
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/jinja2/environment.py", line 997, in get_template
    return self._load_template(name, globals)
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/jinja2/environment.py", line 958, in _load_template
    template = self.loader.load(self, name, self.make_globals(globals))
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/jinja2/loaders.py", line 137, in load
    code = environment.compile(source, name, filename)
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/jinja2/environment.py", line 749, in compile
    source = self._parse(source, name, filename)
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/jinja2/environment.py", line 606, in _parse
    return Parser(self, source, name, filename).parse()
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/jinja2/parser.py", line 1038, in parse
    result = nodes.Template(self.subparse(), lineno=1)
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/jinja2/parser.py", line 1012, in subparse
    add_data(self.parse_tuple(with_condexpr=True))
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/jinja2/parser.py", line 725, in parse_tuple
    args.append(parse())
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/jinja2/parser.py", line 523, in parse_expression
    return self.parse_condexpr()
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/jinja2/parser.py", line 528, in parse_condexpr
    expr1 = self.parse_or()
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/jinja2/parser.py", line 543, in parse_or
    left = self.parse_and()
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/jinja2/parser.py", line 552, in parse_and
    left = self.parse_not()
  File "/home/austinsoft/.virtualenvs/myvirtualenv/lib/python3.6/site-packages/jinja2/parser.py", line 560, in parse_not
    if self.stream.current.test("name:not"):
AttributeError: 'Token' object has no attribute 'test'

[edit by admin: formatting]

deleted-user-3967093 | 7 posts | June 17, 2021, noon | permalink

What are the contents of the template? What happens if you don't pass in any context variables at all?

giles | 11800 posts | PythonAnywhere staff | June 17, 2021, 3:23 p.m. | permalink

template is

<html>
    <head>
        <title>Sample app</title>
    </head>
    <body>
        <h1>{{ result.title }}</h1>
        <p><a href="/docs">Docs</a></p>
        <p><a href="/about">About</a></p>
        <p><a href="/">Home</a></p>
    </body>
</html>

simplified app is:

from flask import Flask, render_template

app = Flask(__name__)

@app.route("/")
def homepage():
    return render_template("index.html", result={"title": "test0"})

@app.route("/docs")
def docs():
    return render_template("index.html", result={"title": "test1"})

@app.route("/about")
def about():
    return render_template("index.html", result={"title": "test2"})

if __name__ == "__main__":
    app.run()

if I do not pass any variables and remove the {{ result.title }} it renders correctly if I do return render_template("index.html", title="test") it gives the same error

[edit by admin: formatting]

deleted-user-3967093 | 7 posts | June 17, 2021, 4:35 p.m. | permalink

If you're passing in a dict for the result context variable, should you not be using

<h1>{{ result['title'] }}</h1>

...in the template?

giles | 11800 posts | PythonAnywhere staff | June 17, 2021, 6:01 p.m. | permalink

Same error with <h1>{{ result['title'] }}</h1> but thanks for reply

deleted-user-3967093 | 7 posts | June 17, 2021, 6:26 p.m. | permalink

End result is always AttributeError: 'Token' object has no attribute 'test' What does this even mean?

deleted-user-3967093 | 7 posts | June 17, 2021, 6:28 p.m. | permalink

Forgot to add my original app was working just fine until it was not LOL It works fine on my local machine using the localhost:5000 Flask server It is running in vutualenv, I have tried deleting the virtual folder and creating it again, but still the same error as soon as I try to pass even the simplest variable to jinja

deleted-user-3967093 | 7 posts | June 17, 2021, 6:33 p.m. | permalink

Looks like problem other people encountered and solved.

fjl | 4352 posts | PythonAnywhere staff | June 18, 2021, 2:19 p.m. | permalink

Hi, yep that looks like the problem. I have python 3.9 on my local machine and it works fine. cannot alter that on pythonanywhere, so looks like i will have to regress to an earlier version of jinjs. Thanks for the reply. Mike.

deleted-user-3967093 | 7 posts | June 19, 2021, 1:03 p.m. | permalink

Actually you can use Python 3.9 now -- you'd need to change your system image to the newest one ("glastonbury"), which is deployed, but not fully released yet. See: https://help.pythonanywhere.com/pages/ChangingSystemImage/ (you won't see "glastonbury" mentioned there yet, but it will be shown on your Account page).

pafk | 2973 posts | PythonAnywhere staff | June 19, 2021, 8:03 p.m. | permalink

Hi, thank you. moving to a different image ( 3.9 ) fixed it. Mike.

deleted-user-3967093 | 7 posts | June 20, 2021, 7:42 a.m. | permalink

Excellent, thanks for confirming that!

pafk | 2973 posts | PythonAnywhere staff | June 20, 2021, 9:20 a.m. | permalink