CS50 Final Project: Unique URL for each user of my flask app

Question

For the final project, I am trying to implement a flask application where people may write diaries and read others' diaries. I would like to create a unique URL for each user that shows the diaries that user published, however, I keep getting this HTTP 404 Not Found Error as I test-run the application. I think that is (not only) because every time I flask run the application and open up the web server, it is routed to https://ide50-chanchunhei.cs50.io/ instead of https://ide50-chanchunhei.cs50.io/index/username. If, instead of flask run the application and opening up the web server, I type http://ide50-chanchunhei.cs50.io/login into my browser, rather than getting back an HTTP 404 Not Found Error, I get this one: werkzeug.routing.BuildError: Could not build url for endpoint 'index'. Did you forget to specify values ['username']?. Anyways, my code is as follow:

application.py

@app.route("/index/<username>")
@login_required
def index(username):
    """Cover page: read your own diaries."""

    # lock the cover page until writer published first blog entry
    diaries = db.execute("SELECT diaries, date FROM diaries WHERE username = :username ORDER by date DESC", username=session.get("user_id"))
    if len(diaries) == 0:
     return dumbo("Welcome to FoToM!")

 return render_template("index.html", diaries=diaries, username=session.get("user_id"))

helpers.py

def login_required(f):
    """
    Decorate routes to require login.

    http://flask.pocoo.org/docs/0.11/patterns/viewdecorators/
    """

    @wraps(f)
    def decorated_function(*args, **kwargs):
        if session.get("user_id") is None:
            return redirect(url_for("login", next=request.url))
        return f(*args, **kwargs)
    return decorated_function

For your reference, my current code, unlike Problem Set 7, does not have any @app.route("/") now. And these are some online resources I made references to in implementing unique URLs: Link1, Link2, Link3, and Link4.

Thanks in advance!

Answer 1

Based on 1) what I don't know and 2) what you don't show:

• Instead of https://ide50-chanchunhei.cs50.io/index/username, does https://ide50...../index?username=something work?

• werkzeug.routing.BuildError: Could not build url for endpoint 'index'. Did you forget to specify values ['username'] indicates you are "calling" index something similar to pset7 code (return redirect(url_for("index"))), but are not sending the (required) username parameter. From URL Building in the Quickstart doc:

It accepts the name of the function as first argument and a number of keyword arguments,

As this example url_for('profile', username='John Doe') from the same source shows.

FWIW - this return render_template("index.html", diaries=diaries, username=session.get("user_id")) looks "loopy" (see 1) above). The function requires a username, so you can't automagically send it one after you've already called the function without a username.

ADDED:

• 404 response is because there is no root path (@app.route("/"))
• Time for the flask debugger? When it dumps the Traceback, look through the "blue" lines for the return redirect(url_for("index".... line. Hover and you will see a "console" icon at the right. Click that to open a console. (Find the pin in the flask terminal). One possibility is username=None because "If the value of a query argument is None, the whole pair is skipped.". But you'll need to use your eyes to examine, troubleshoot and debug. Good luck!