PSET 9 Finance - NONETYPE error after querying db

Question

Need help solving this error:

File "/workspaces/finance/app.py", line 223, in sell

if available_shares < shares:

TypeError: '<' not supported between instances of 'NoneType' and 'int'

I'm stuck and any help is much appreciated! Thank you!

@app.route("/sell", methods=["GET", "POST"])
@login_required
def sell():
"""Sell shares of stock"""
user_id = session["user_id"]
symbols = db.execute("SELECT symbol FROM trades WHERE user_id = ? GROUP BY symbol", user_id)

if request.method == "POST":
    symbol = request.form.get("symbol")
    shares = int(request.form.get("shares"))

    # User did not provide any symbol
    if not symbol:
        return apology("Please select stock code", 400)

    # User did not provide valid quantity
    elif not shares:
        return apology("Please provide valid quantity", 400)

    available_shares = db.execute("SELECT SUM(quantity) AS subtotal FROM trades WHERE user_id = ? AND symbol = ?", user_id, symbol)[0]["subtotal"]

    if available_shares < shares:
        return apology("Insufficient shares to sell")
    else:
        cash = db.execute("SELECT cash FROM users WHERE id = ?", user_id)[0]["cash"]
        stock_price = lookup(symbol)["price"]
        total_price = shares * stock_price

        db.execute("UPDATE users SET cash = ? WHERE id =?", cash+total_price, user_id)
        db.execute("INSERT INTO trades (user_id, buy_sell, symbol, quantity, price, total_trade_value) VALUES (?, ?, ?, ?, ?, ?)", user_id, "(SOLD)", symbol, -shares, stock_price, total_price)
        return redirect("/")

else:
    return render_template("sell.html", symbols=symbols)


    

Answer 1

SOLVED: Traced my error to a mistake in my http code. I defined a VALUE for symbol. Problem solved when I deleted it.