Redirect stdout to a Jinja variable

Question

I would like to redirect sys.stdout to a Jinja variable so that I can see it in the frontend (I'm using Flask server). How do I do this? Is there a better way to get the stdout to the HTML template?

This is what I have tried:

sys.stdout = jinja2.Template("<div id='console'>{{ console }}</div>")

But I get this error when using print:

AttributeError: 'Template' object has no attribute 'write'
Exception ignored in: <Template memory:b4a2a9f0>
AttributeError: 'Template' object has no attribute 'flush'

I've seen posts like this, but I'm not sure how to implement it in my case. Any help is appreciated.

score 1 · Accepted Answer · answered Mar 21 '22 at 08:01

If I understand what you would like to do you should write something similar (then adjust it according to your needs):

import sys
from io import StringIO

import jinja2
from flask import Flask

app = Flask(__name__)


@app.route("/test")
def home():
    old_stdout = sys.stdout
    sys.stdout = mystdout = StringIO()
    print("test")
    sys.stdout = old_stdout
    return jinja2.Template("<div id='console'>my output = {{ console }}</div>").render(
        console=mystdout.getvalue()
    )

if __name__ == "__main__":
    app.run("0.0.0.0", 80, True)

Redirect stdout to a Jinja variable

1 Answers1