类型错误：列表索引必须是整数 - 处理金钱

Question

我正在尝试“执行”股票的（假）买单。cash = cashcheck["cash"]我在该行遇到错误。它说索引必须是整数，但我们谈论的是钱，所以它不能是一个整数，因为涉及小数......我认为。

非常感谢您的帮助！

代码：

@app.route("/buy", methods=["GET", "POST"])

@login_required

def buy():

    """Buy shares of stock"""

    if request.method == "GET":

        return render_template("/buy.html")

    else:

        # collect user input - symbol

        symbol = request.form.get("symbol").upper()

        # if input is blank or symbol doesn't exist, return apology

        if not symbol:

            return apology("You must enter a stock symbol.", 300)

        # collect user input - # of shares

        shares = int(request.form.get("shares"))

        # if blank or not a positive integer, return apology

        if not shares:

            return apology("Enter a valid number of shares.", 300)

        # pull current price info from API

        quote = lookup(symbol)

        shareprice = quote["price"]

        totalprice = shareprice * shares

        # check users table to see how much cash user has

        cashcheck = db.execute("SELECT cash FROM users WHERE id = :userid", userid = session["user_id"])

        cash = cashcheck["cash"]

        if cash >= totalprice:

            # in transactions table, insert userID, symbol, shares, shareprice, and totalprice

            # transID should be autogenerated and autoincremented.  date is also autofilled by SQLite.

            db.execute("INSERT INTO transactions (userID, symbol, shares, shareprice, totalprice) VALUES (:userid, :symbol, :shares, :shareprice, :totalprice)",

            userid=session["user_id"], symbol=symbol, shares=shares, shareprice=shareprice, totalprice=totalprice)

            cash = cash - totalprice

            # update cash balance

            db.execute("UPDATE users SET cash = :cash WHERE id = :userid", userid = session["user_id"])

            #return index

            return ("/")

        else:

            # else, return apology (not enough cash)

            return apology("Not enough cash balance to make execute this order.", 300)

Answer 1

cashcheck是与查询匹配的行的列表。如果您只希望匹配一行，请使用cashcheck[0]["cash"].