request.referrer не перенаправляет на предыдущий URL

Question

У меня трудное время, так как я не мог понять, как перенаправить на предыдущий URL. Когда я тестировал request.referrer 10 дней go, он работал, но теперь он больше не работает, и вместо этого я получаю тот же URL. Я создаю логин Google. Вот код:

@main.route("/post/<int:post_id>", methods=["GET", "POST"])
def post(post_id):
    post = Posts.query.filter_by(id=post_id).one()
    comments = post.comments

    if post == None:
        return ('Error')
    elif current_user.is_authenticated:
        return render_template("show_post0.html", post=post, comments=comments, username=current_user.user_name, userimage=current_user.user_photo)

    return render_template("show_post_login.html", post=post, comments=comments)




# redirect to previous url
def redirect_url(default='main.post'):
    return request.args.get('next') or \
           request.referrer or \
           url_for(default)



@main.route("/login/callback")
def callback():
    # Get authorization code Google sent back to you
    code = request.args.get("code")

    # Find out what URL to hit to get tokens that allow you to ask for
    # things on behalf of a user
    google_provider_cfg = get_google_provider_cfg()
    token_endpoint = google_provider_cfg["token_endpoint"]

    # Prepare and send request to get tokens! Yay tokens!
    token_url, headers, body = client.prepare_token_request(
        token_endpoint,
        authorization_response=request.url,
        redirect_url=request.base_url,
        code=code,
    )
    token_response = requests.post(
        token_url,
        headers=headers,
        data=body,
        auth=(GOOGLE_CLIENT_ID, GOOGLE_CLIENT_SECRET),
    )

    # Parse the tokens!
    client.parse_request_body_response(json.dumps(token_response.json()))

    # Now that we have tokens (yay) let's find and hit URL
    # from Google that gives you user's profile information,
    # including their Google Profile Image and Email
    userinfo_endpoint = google_provider_cfg["userinfo_endpoint"]
    uri, headers, body = client.add_token(userinfo_endpoint)
    userinfo_response = requests.get(uri, headers=headers, data=body)

    # We want to make sure their email is verified.
    # The user authenticated with Google, authorized our
    # app, and now we've verified their email through Google!
    if userinfo_response.json().get("email_verified"):
        unique_id = userinfo_response.json()["sub"]
        users_email = userinfo_response.json()["email"]
        picture = userinfo_response.json()["picture"]
        users_name = userinfo_response.json()["given_name"]
    else:
        return "User email not available or not verified by Google.", 400


    # Create a user in our db with the information provided
    # by Google
    author = Author(
        google_id=unique_id, user_name=users_name, user_email=users_email, user_photo=picture
    )


    user = Author.query.filter_by(google_id=unique_id).first()
    # Doesn't exist? Add to database
    if user:
        # Begin user session by logging the user in
        login_user(user)


    else:
        db.session.add(author)
        db.session.commit()
        login_user(author)

# Send user back to homepage
print("##############", request.args.get('next')) # the result is None

print("##############", request.referrer ) # the result is the same URL when login to Google, so the page keep loading again without returning to the previous page. That's strange because the first time I used this method, it worked perfectly!

return redirect(redirect_url())

Я мог бы перенаправить прямо на маршрут Post, но я хочу использовать этот метод в нескольких маршрутах.

Заранее спасибо!