cs50 金融：注册错误“列表索引超出范围”

Question

至此，我已经完成了买入、报价、注册、索引功能。当我第一次编写注册函数时，一切正常，但是当我编写其余部分，然后返回尝试用新用户名注册时，我收到了 500 内部服务器错误。

这是我在app.py中的注册函数

@app.route("/register", methods=["GET", "POST"])
def register():
    """Register user. FIRST"""
    #Forget any user_id
    session.clear()

    #User reached route via POST (as by submitting a form via POST)
    if request.method == "POST":

        #Ensure username was submitted
        if not request.form.get("username"):
            return apology("must provide username", 400)

        #Ensure password was submitted
        elif not request.form.get("password"):
            return apology("must provide password", 400)

        #Ensure password confirmation was submitted
        elif not request.form.get("confirmation"):
            return apology("must confirm password", 400)

        #Ensure password and confirmation match
        elif request.form.get("password") != request.form.get("confirmation"):
            return apology("passwords do not match", 400)

        #Query database for username
        rows = db.execute("SELECT * FROM users WHERE username = ?", request.form.get("username"))

        #Ensure username does not already exist
        if len(rows) != 0:
            return apology("username already exists", 400)

        #Insert new user into database
        db.execute("INSERT INTO users (username, hash) VALUES(?, ?)",
                   request.form.get("username"), generate_password_hash(request.form.get("password")))

        #Query database for newly inserted user
        row = db.execute("SELECT * FROM users WHERE username = ?",request.form.get("username"))

        #Remember which user has logged in
        session["user_id"] = rows[0]["id"]

        #Redirect user to homepage
        return redirect("/")

    #User reached route via GET (as by cliking a link or via redirect)
    else:
        return render_template("register.html")

任何帮助将不胜感激，如果您需要其他函数或文件来解决此问题，请告诉我，谢谢！

Answer 1

这表示

session["user_id"] = rows[0]["id"]

行复数。前面的行将 sql 结果设置为行单数。在文档（或课件或我的记忆）中的某处提到，如果插入的表具有整数主键，则

insert

查询将返回分配的键。您可以使用该返回值并节省一两步。